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Mating and spawning are distinct events in blue crab reproduction. Males may mate several times and undergo no major changes in morphology during the process. Female blue crabs mate only once in their lifetimes during their pubertal, or terminal, molt. During this transition, the abdomen changes from a triangular to a semicircular shape. Mating in blue crab is a complex process that requires precise timing of mating at the time of the female's terminal molt. It generally occurs during the warmest months of the year. Prepubertal females migrate to the upper reaches of estuaries, where males typically reside as adults. To ensure that a male can mate, he actively seeks a receptive female and guards her for up to seven days until she molts, when insemination occurs. Crabs compete with other individuals before, during, and after insemination, so mate guarding is very important for reproductive success. After mating, a male must continue to guard the female until her shell has hardened. Inseminated females retain spermatophores for up to one year, which they use for multiple spawnings in high salinity water. During spawning, a female extrudes fertilized eggs onto her swimmerets and carries them in a large egg mass, or sponge, while they develop. Females migrate to the mouth of the estuary to release the larvae, the timing of which is believed to be influenced by light, tide, and lunar cycles. Blue crabs have high fecundity; females may produce up to 2 million eggs per brood.
Migration and reproduction patterns differ between crab populations along the East Coast and the Gulf of Mexico. A distinct and large-scale migration occurs in Chesapeake Bay, where C. sapidus undergoes a seasonal migration of up to several hundred miles. In the middle and upper parts of the bay, mating peaks in mid- to late summer, while in the lower bay, peaks in mating activity occur during spring and late summer through early fall. Changes in salinity and temperature may impact time of mating because both factors are important during the molting process. After mating, the female crab travels to the southern portion of the Chesapeake, using ebb tides to migrate from areas of low salinity to areas of high salinity, fertilizing her eggs with sperm stored during her single mating months or almost a year before. | Callinectes sapidus | Wikipedia | 479 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Spawning events in the Gulf of Mexico are less pronounced than in estuaries along the East Coast, like the Chesapeake. In northern waters of the Gulf of Mexico, spawning occurs in the spring, summer, and fall, and females generally spawn twice. During spawning, females migrate to high -salinity waters to develop a sponge, and return inland after hatching their larvae. They develop their second sponge inland, and again migrate to the high-salinity waters to hatch the second sponge. After this, they typically do not re-enter the estuary. Blue crabs along the southernmost coast of Texas may spawn year-round.
Commercial importance
Range of fisheries
Commercial fisheries for C. sapidus exist along much of the Atlantic coast of the United States, and in the Gulf of Mexico. Although the fishery has been historically centered on the Chesapeake Bay, contributions from other localities are increasing in importance. In the past two decades, most commercial crabs have been landed in four states: Maryland, Virginia, North Carolina, and Louisiana. Weight and value of harvests since 2000 are listed below.
History of the crab fishery
As early as the 1600s, the blue crab was an important food item for Native Americans and English settlers in the Chesapeake Bay area. Soft and hard blue crabs were not as valuable as fish, but gained regional popularity by the 1700s. Throughout their range, crabs were also an effective bait type for hook-and-line fisheries. Rapid perishing limited the distribution and hindered the growth of the fishery. Advances in refrigeration techniques in the late 1800s and early 1900s increased demand for blue crab nationwide.
Atlantic Coast
The early blue crab fishery along the Atlantic Coast was casual and productive because blue crabs were extremely abundant. In the lower Chesapeake Bay, crabs were even considered a nuisance species because they frequently clogged the nets of seine fishermen. Early on, the blue crab fishery of the Atlantic states was well documented. Atlantic states were the first to regulate the fishery, particularly the Chesapeake states. For example, after observing a slight decline in harvest, the fishing commissions of Virginia and Maryland put size limits into place by 1912 and 1917, respectively. Catch-per-unit-effort at the time was determined by packing houses, or crab processing plants. | Callinectes sapidus | Wikipedia | 454 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Gulf of Mexico
The early history of the recreational blue crab fishery in the Gulf of Mexico is not well known. Commercial crabbing was first reported in the Gulf of Mexico in the 1880s. Early crab fishermen used long-handled dip nets and drop nets among other simple fishing gear types to trap crabs at night. Blue crab spoiled quickly, which limited distribution and hindered the growth of the fishery for several decades. The first commercial processing plant in Louisiana opened in Morgan City in 1924. Other plants opened soon after, although commercial processing of hard blue crabs was not widespread until World War II.
Louisiana fishery
Louisiana now has the world's largest blue-crab fishery. Commercial harvests in the state account for over half of all landings in the Gulf of Mexico. The industry was not commercialized for interstate commerce until the 1990s, when supply markedly decreased in Maryland due to problems (see above) in Chesapeake Bay. Since then, Louisiana has steadily increased its harvest. In 2002, Louisiana harvested 22% of the nation's blue crab. That number rose to 26% by 2009 and 28% by 2012. The vast majority of Louisiana crabs are shipped to Maryland, where they are sold as "Chesapeake" or "Maryland" crab. Louisiana's harvest remained high in 2013, with 17,597 metric tons of blue crab valued at $51 million. In addition to commercial harvesting, recreational crabbing is very popular along Louisiana's coast.
Chesapeake Bay fishery
The Chesapeake Bay has had the largest blue crab harvest for more than a century. Maryland and Virginia are usually the top two Atlantic coast states in annual landings, followed by North Carolina. In 2013, crab landings were valued at $18.7 million from Maryland waters and $16.1 million from Virginia waters. Although crab populations are currently declining, blue crab fishing in Maryland and Virginia remains a livelihood for thousands of coastal residents. As of 2001, Maryland and Virginia collectively had 4,816 commercial crab license holders. Three separate licenses are required for each of the three major jurisdictional areas: Maryland, the Potomac River, and Virginia waters. While the Bay's commercial sector lands the majority of hard crab landings and nearly all peeler or soft crab landings, the recreational fishery is also significant. In 2013, an estimated of blue crab were harvested recreationally. | Callinectes sapidus | Wikipedia | 462 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Recent decline
Blue crab populations naturally fluctuate with annual changes in environmental conditions. They have been described as having a long-term dynamic equilibrium, which was first noted after irregular landings data in the Chesapeake in 1950. This tendency may have made it difficult for managers to predict the severe decline of the Chesapeake's blue crab populations. Once considered an overwhelmingly abundant annoyance, the declining blue crab population is now the subject of anxiety among fishermen and managers. Over the decade between the mid-1990s to 2004, the population fell from 900 million to around 300 million, and harvest weight fell from . Revenue fell further, from $72 million to $61 million. Long-term estimates say that the overall Chesapeake population decreased around 70% in the last few decades. Even more alarming, the number of females capable of reproducing, known as spawning age females, has plummeted 84% in just a few decades. Survival and addition of juveniles to the harvestable crab population is also low. Many factors are to blame for low blue crab numbers, including high fishing pressure, environmental degradation, and disease prevalence. The 2018 reduction in H-2B visas available for seasonal workers is affecting Maryland's 20 crab processors, which typically employ about 500 foreign workers, but the effect this will have on the crab fishery is not yet clear.
Crabbing gear
Many types of gear have been used to catch blue crabs along the Atlantic and Gulf Coasts. Initially, people used very simple techniques and gear, which included hand lines, dip nets, and push nets among a variety of other gear types. The trotline, a long baited twine set in waters 5–15 feet deep, was the first major gear type used commercially to target hard crabs. Use of commercial trotlines is now mostly limited to the tributaries of the Chesapeake Bay. In the Gulf of Mexico, trotline use drastically declined after invention of the crab pot in 1938. Crab pots are rigid, box-like traps made of hexagonal or square wire mesh. They possess between two and four funnels that extend into the trap, with the smaller end of the funnel inside of the trap. A central compartment made of smaller wire mesh holds bait. Crabs attracted by odorant plumes from the bait, often an oily fish, enter the trap through the funnels and cannot escape. | Callinectes sapidus | Wikipedia | 473 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Bycatch
Species other than blue crab are often caught incidentally in crab pots, including fish, turtles, conch, and other crab species. In Georgia, hermit crabs (Pagurus spp.), channeled whelk (Busycon canaliculatum), spider crabs (Libinia spp.), and stone crabs (Menippe mercenaria) were the most common species observed as bycatch in commercial crab pots. Of important concern is the diamondback terrapin, Malaclemys terrapin. The blue crab and diamondback terrapin have overlapping ranges along the East and Gulf Coasts of the United States. Because the funnels in a crab pot are flexible, small terrapins may easily enter and become entrapped. Traps are checked every 24 hours or less, frequently resulting in drowning and death of terrapins. Crab pot bycatch may reduce local terrapin populations to less than half. To reduce terrapin entrapment, bycatch reduction devices (BRDs) may be installed on each of the funnels in a crab pot. BRDs effectively reduce bycatch (and subsequently mortality) of small terrapins without affecting blue crab catch.
Efforts to manage fisheries
Because of its commercial and environmental value, C. sapidus is the subject of management plans over much of its range. In 2012, the C. sapidus population in Louisiana was recognized as a certified sustainable fishery by the Marine Stewardship Council. It was the first and remains the only certified sustainable blue crab fishery worldwide. For the state to maintain its certification, it must undergo annual monitoring and conduct a full re-evaluation five years after the certification date.
Sports
The blue crab is the namesake of the Jersey Shore BlueClaws team in minor-league baseball playing in the South Atlantic League. They are located in Lakewood, New Jersey, and are a high-A affiliate of the Philadelphia Phillies.
Blue crabs are also the namesake of the Southern Maryland Blue Crabs, a professional baseball team located in Waldorf, Maryland. | Callinectes sapidus | Wikipedia | 414 | 574796 | https://en.wikipedia.org/wiki/Callinectes%20sapidus | Biology and health sciences | Crabs and hermit crabs | Animals |
Mangrove crabs are crabs that live in and around mangroves. They belong to many different species and families and have been shown to be ecologically significant by burying and consuming leaf litter. Mangrove crabs have a variety of phylogenies because mangrove crab is an umbrella term that encompasses many species of crabs. Two of the most common families are sesarmid and fiddler crabs. They are omnivorous and are predated on by a variety of mammals and fish. They are distributed widely throughout the globe on coasts where mangroves are located. Mangrove crabs have wide variety of ecological and biogeochemical impacts due to the biofilms that live in symbiosis with them as well as their burrowing habits. Like many other crustaceans, they are also a human food source and have been impacted by humans as well as climate change.
Species and distribution
Current estimates place the number of mangrove crab species at 481 in 6 different families, with new species being discovered frequently. Mangrove crabs primarily live in the Indo-West Pacific region in mudflats along tropical coasts. The largest habitats for mangrove crabs are in Southeast Asia, South America, and Northern Australia. As their name suggests, they are primarily found among mangrove tree forests and form symbiotic relationships with the trees, restricting their habitat to where the trees can grow.
Phylogeny
A variety of different species are what makeup the umbrella term of mangrove crabs. The two main crabs that typically dominate mangrove ecosystems are the sesarmid (Grapsidae) and fiddler crabs (Ocypodidae). The main difference between the two crab groups is their foraging habits. Litter ingested by sesarmid crabs forms fragmented organic material that helps stimulate microbial respiration, in contrast fiddler crabs remove reactive organic carbon. Mangrove crabs are a part of the Animalia kingdom and are put into the Arthropoda phylum, Malacostraca class, and Decapoda order. Mangrove crabs can be classified into six different families: Camptandriidae, Dotillidae, Macrophthalmidae, Ocypodidae, Sesarmidae, and Oziidae. | Mangrove crab | Wikipedia | 439 | 574874 | https://en.wikipedia.org/wiki/Mangrove%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Types of mangrove crabs
Sesarmid crabs
Fiddler crabs
Aratus pisonii, Americas
Haberma, genus of small mangrove crabs, Indo-Pacific, including:
Haberma tingkok, Hong Kong
Metopograpsus messor, Indo-Pacific
Metopograpsus thukuhar, Indo-Pacific
Neosarmatium meinerti, Indo-Pacific
Neosarmatium smithi, Indo-Pacific
Parasesarma leptosoma, western Indian Ocean
Perisesarma, genus with 23 species, primarily Indo-Pacific, with two West African species, including:
Perisesarma bidens, Indo-Pacific
Perisesarma guttatum, western Indian Ocean
Scylla serrata, Indo-Pacific
Scylla tranquebarica, Indo-Pacific
Sesarma, genus with close to 20 species, many of which live in mangroves, Americas, Indo-Pacific
Ucides cordatus, western Atlantic Ocean
Ecology and biogeochemistry
Diet and predators
When young, mangrove crabs get most of their nutrients from polychaete worms and a multitude of microorganisms found living in the sediments and leaves of their environment. As they grow older mangrove crabs are generally detritivores with their diet consisting of already dead organic material. Mangrove crabs consume a large amount of plant material but are primarily omnivorous. In the mangrove swamp this includes dead leaves and corpses of other crustaceans, even that of their own species. In some cases, mangrove crabs may also eat fresh mangrove leaves. Mangrove crabs are predated on by wading birds, fish, sharks, monkeys, hawks, and raccoons. The larvae of mangrove crabs is a major source of food for juvenile fish in waterways near the crabs. Adult mangrove crabs are food for the crab plover among other protected species. To protect themselves the crabs can climb trees. The only other crustaceans that climb trees are hermit crabs.
Habitat and ecosystem engineering | Mangrove crab | Wikipedia | 402 | 574874 | https://en.wikipedia.org/wiki/Mangrove%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Mangrove crabs often construct and inhabit burrows in mangrove sediment. These burrows aid them in enduring the extremes that can be found in mangroves at high and low tide, allowing them to maintain more constant and ideal temperatures and oxygen levels. These constants can additionally aid other small benthic fauna, like polychaetes and juvenile crabs. Mangrove crabs may plug their burrows at intervals determined by their circadian rhythms, or they may leave them open. The variety in structures and maintenance of these burrows may lead to a variety of different impacts on mangrove sediments, such as increasing or decreasing erodibility. Fiddler crabs generally have very simple 10–40 cm “J-shaped” burrows, while sesarmid crabs that burrow often create complex, branching burrows that can reach over 100 cm in depth. Both types of crab significantly increase the surface area of the sediment and water/air interface to similar extents when scaled for relative abundance. These burrows also result in significant burial and downward travel of mangrove leaves. The burrowing dynamics of mangrove crabs dramatically impacts ecosystems, these dynamics were impacted by both abiotic factors like soil composition, and biotic factors like root depth and tree density.
Mangrove crabs modify particle size, nutrient availability, particle distribution, redox reactions, and organic matter. Aeration allows for additional microbial decomposition, oxidation of iron, and reduction of sulfur by anaerobic microbes. This leads to extremely high pyrite concentrations in mangrove soils, and removal of sulfides that negatively impact plant growth. Surface soils are similarly impacted when mixed by mangrove crab legs.
Depending on its nitrogen content, burial of detritus in crab burrows can stimulate microbial growth and activity and lead to variation in mangrove soils’ carbon dioxide efflux, ammonium content, and nitrate content.
The feces of mangrove crabs may help form a coprophagous food chain which contributes to mangrove secondary production. | Mangrove crab | Wikipedia | 385 | 574874 | https://en.wikipedia.org/wiki/Mangrove%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
Biofilms
Biofilm endosymbiosis occurs on the gills of some mangrove crabs, namely Aratus pisonii and Minuca rapax. Each species of these mangrove crabs likely have distinct bacterial compositions. These microbial biofilms are locations of nitrogen transformation, particularly nitrogen fixation. Bacteria like Cyanobacteria, Alphaproteobacteria, Actinobacteria, and Bacteroidota have been found on mangrove crab carapaces. The biofilms served as a net nitrogen sink and a source of ammonium and dissolved nitrogen to the environment. The importance of the biofilm may be dependent on if the crabs live primarily in burrows or outside burrows. Crabs that live outside burrows may consume their nitrogen from microphytobenthos, while crabs that live inside their burrows may rely more on their associated microbes.
Human impacts
Climate change
Ideal mangrove crab habitats rely heavily on coastal depth and surface temperature. Climate change due to anthropogenic activities is likely to create fluctuations in these two factors, driving the mangrove crab habitats to higher latitudes. As a result, it is predicted that mangrove habitats will continually shrink for the majority of crab species. This shrinking of habitat space isolates crab communities and shrinks genetic diversity, making many species more vulnerable to extinction.
Crabbing
Like many other crustaceans, mangrove crabs have historically been caught, prepared and eaten by people all over the world. Crab meat can be prepared simply by boiling the crab either dead or alive until the shell turns from black to red. This practice may be threatened by human activities, however, as microplastics have been found to be abundantly common in the gills of mangrove crabs due to human pollution. This not only negatively affects the health of the crabs, but could affect the health of humans who consume them.
Land use change
Around 6,000 km2 of mangrove was deforested between 1996 and 2016, usually redeveloped for fish and shrimp aquaculture, rice cultivation, palm oil plantations, and sometimes urbanization. Diversity of mangrove crabs does not seem to be negatively affected in abandoned aquaculture plots, though logging has significant negative effects on mangrove crab diversity. | Mangrove crab | Wikipedia | 437 | 574874 | https://en.wikipedia.org/wiki/Mangrove%20crab | Biology and health sciences | Crabs and hermit crabs | Animals |
A motorboat or powerboat is a boat that is exclusively powered by an engine; faster examples may be called "speedboats".
Some motorboats are fitted with inboard engines, others have an outboard motor installed on the rear, containing the internal combustion engine, the gearbox and the propeller in one portable unit. An inboard-outboard contains a hybrid of an inboard and an outboard, where the internal combustion engine is installed inside the boat, and the gearbox and propeller are outside.
There are two configurations of an inboard, V-drive and direct drive. A direct drive has the powerplant mounted near the middle of the boat with the propeller shaft straight out the back, where a V-drive has the powerplant mounted in the back of the boat facing backwards having the shaft go towards the front of the boat then making a V towards the rear.
Overview
A motorboat is a small craft with one or more engines for propulsion. Motorboats are commonly used for work, recreation, sport, or racing.
Boat engines vary in shape, size, and type. These include inboard, outboard (integrating, the engine, gearbox, and propeller in one portable unit mounted in the rear), and inboard-outboard (or “sterndrive”, which mounts the engine inboard and the rest outboard).
Fuel types include gasoline, diesel, gas turbine, rotary combustion or steam.
High performance speedboats can reach speeds of over 50 knots. Their high speed and performance can be attributed to their hull technology and engine. With a more powerful and heavier engine, an appropriate hull shape is needed. High performance boats include yachts, HSIC (high speed interceptor craft) and racing powerboats.
A V-type hull helps a boat cut through the water. A deep V-hull helps keep the boat's bow down at low speeds, improving visibility. V-hulls also improve a boat's speed and maneuvering capabilities. They stabilize a boat in rough conditions.
History
Invention
Although the screw propeller had been added to an engine (steam engine) as early as the 18th century in Birmingham, England, by James Watt, boats powered by a petrol engine only came about in the later part of the 19th century with the invention of the internal combustion engine. | Motorboat | Wikipedia | 460 | 574964 | https://en.wikipedia.org/wiki/Motorboat | Technology | Naval transport | null |
The earliest boat to be powered by a petrol engine was tested on the Neckar River by Gottlieb Daimler and Wilhelm Maybach in 1886, when they tested their new "longcase clock" engine. It had been constructed in the former greenhouse (converted into a workshop) in Daimler's back yard. The first public display took place on the Waldsee in Cannstatt, today a suburb of Stuttgart, at the end of that year. The engine of this boat had a single cylinder of 1 horse power. Daimler's second launch in 1887 had a second cylinder positioned at an angle of 15 degrees to the first one, and was known as the "V-type".
The first successful motor boat was designed by the Priestman Brothers in Hull, England, under the direction of William Dent Priestman. The company began trials of their first motorboat in 1888. The engine was powered with kerosene and used an innovative high-tension (high voltage) ignition system. The company was the first to begin large scale production of the motor boat, and by 1890, Priestman's boats were successfully being used for towing goods along canals.
Another early pioneer was Mr. J. D. Roots, who in 1891 fitted a launch with an internal combustion engine and operated a ferry service between Richmond and Wandsworth along the River Thames during the seasons of 1891 and 1892.
The eminent inventor Frederick William Lanchester recognized the potential of the motorboat and over the following 15 years, in collaboration with his brother George, perfected the modern motorboat, or powerboat. Working in the garden of their home in Olton, Warwickshire, they designed and built a river flat-bottomed launch with an advanced high-revving engine that drove via a stern paddle wheel in 1893. In 1897, he produced a second engine similar in design to his previous one but running on benzene at 800 r.p.m. The engine drove a reversible propeller. An important part of his new engine was the revolutionary carburettor, for mixing the fuel and air correctly. His invention was known as a "wick carburetor", because fuel was drawn into a series of wicks, from where it was vaporized. He patented this invention in 1905. | Motorboat | Wikipedia | 463 | 574964 | https://en.wikipedia.org/wiki/Motorboat | Technology | Naval transport | null |
The Daimler Company began production of motor boats in 1897 from its manufacturing base in Coventry. The engines had two cylinders and the explosive charge of petroleum and air was ignited by compression into a heated platinum tube. The engine gave about six horse-power. The petrol was fed by air pressure to a large surface carburettor and also an auxiliary tank which supplied the burners for heating the ignition tubes. Reversal of the propeller was effected by means of two bevel friction wheels which engaged with two larger bevel friction wheels, the intermediate shaft being temporarily disconnected for this purpose. It was not until 1901 that a safer apparatus for igniting the fuel with an electric spark was used in motor boats.
Expansion
Interest in fast motorboats grew rapidly in the early years of the 20th century. The Marine Motor Association was formed in 1903 as an offshoot of the Royal Automobile Club. Motor Boat & Yachting was the first magazine to address technical developments in the field and was brought out by Temple Press, London from 1904. Large manufacturing companies, including Napier & Son and Thornycroft began producing motorboats.
Early racing
The first motorboating competition was established by Alfred Charles William Harmsworth in 1903. The Harmsworth Cup was envisioned as a contest between nations, rather than between boats or individuals. The boats were originally to be designed and built entirely by residents of the country represented, using materials and units built wholly within that country.
The first competition, held in July 1903, at Cork Harbour in Ireland, and officiated by the Automobile Club of Great Britain and Ireland and the Royal Victoria Yacht Club, was a very primitive affair, with many boats failing even to start. The competition was won by Dorothy Levitt in a Napier launch designed to the specifications of Selwyn Edge. This motorboat was the first proper motorboat designed for high speed. She set the world's first water speed record when she achieved in a steel-hulled, 75-horsepower Napier speedboat fitted with a three-blade propeller. As both the owner and entrant of the boat, "S. F. Edge" was engraved on the trophy as the winner. | Motorboat | Wikipedia | 431 | 574964 | https://en.wikipedia.org/wiki/Motorboat | Technology | Naval transport | null |
An article in the Cork Constitution on 13 July reported "A large number of spectators viewed the first mile from the promenade of the Yacht Club, and at Cork several thousand people collected at both sides of the river to see the finishes." Levitt was then commanded to the Royal yacht of King Edward VII where he congratulated her on her pluck and skill, and they discussed the performance of the motorboat and its potential for British government despatch work.
France won the race in 1904, and the boat Napier II set a new world water speed record for a mile at almost 30 knots (56 km/h), winning the race in 1905.
The acknowledged genius of motor boat design in America was the naval architect John L. Hacker. His pioneering work, including the invention of the V-hull and the use of dedicated petrol engines revolutionized boat design from as early as 1908, when he founded the Hacker Boat Co. In 1911, Hacker designed the Kitty Hawk, the first successful step hydroplane which exceeded the then-unthinkable speed of and was at that time the fastest boat in the world. The Harmsworth Cup was first won by Americans in 1907. The US and England traded it back and forth until 1920. From 1920 to 1933, Americans had an unbroken winning streak. Gar Wood won this race eight times as a driver and nine times as an owner between 1920 and 1933.
Hull type
From a design point of view, a boat’s hull type reflects its use and the waters it will be used it. These include displacement hulls, vee-bottom hulls, modified vee-bottom hulls, deep-vee hulls and trim tabs for vee-bottom hulls. The three main hull materials are wood, reinforced fiberglass and metal. Wood hulls may be made of planks or plywood. Fiberglass hulls are reinforced with balsa wood. Metal hulls are either aluminum or steel.
Some gross configurations of motorboats include skiff, day cruiser, bow rider, pilothouse and cabin cruiser. These vary by such considerations as size, whether they have a deck, cabin, head, is sail, helm position, and additional seating.
Gallery | Motorboat | Wikipedia | 447 | 574964 | https://en.wikipedia.org/wiki/Motorboat | Technology | Naval transport | null |
A submersible is an underwater vehicle which needs to be transported and supported by a larger watercraft or platform. This distinguishes submersibles from submarines, which are self-supporting and capable of prolonged independent operation at sea.
There are many types of submersibles, including both human-occupied vehicles (HOVs) and uncrewed craft, variously known as remotely operated vehicles (ROVs) or unmanned underwater vehicles (UUVs). Submersibles have many uses including oceanography, underwater archaeology, ocean exploration, tourism, equipment maintenance and recovery and underwater videography.
History
The first recorded self-propelled underwater vessel was a small oar-powered submarine conceived by William Bourne (c. 1535 – 1582) and designed and built by Dutch inventor Cornelis Drebbel in 1620, with two more improved versions built in the following four years. Contemporary accounts state that the final model was demonstrated to King James I in person, who may even have been taken aboard for a test dive. There do not appear to have been any further recorded submersibles until Bushnell's Turtle.
The first submersible to be used in war was designed and built by American inventor David Bushnell in 1775 as a means to attach explosive charges to enemy ships during the American Revolutionary War. The device, dubbed Bushnell's Turtle, was an oval-shaped vessel of wood and brass. It had tanks that were filled with water to make it dive and then emptied with the help of a hand pump to make it return to the surface. The operator used two hand-cranked propellers to move vertically or laterally under the water. The vehicle had small glass windows on top and naturally luminescent wood affixed to its instruments so that they could be read in the dark.
Bushnell's Turtle was first set into action on September 7, 1776, at New York Harbor to attack the British flagship . Sergeant Ezra Lee operated the vehicle at that time. Lee successfully brought Turtle against the underside of Eagles hull but failed to attach the charge because of the strong water currents.
Manned submersibles are primarily used by special forces, which can use this type of vessel for a range of specialised missions. | Submersible | Wikipedia | 448 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
Operation
Apart from size, the main technical difference between a "submersible" and a "submarine" is that submersibles are not fully autonomous and may rely on a support facility or vessel for replenishment of power and breathing gases. Submersibles typically have shorter range, and operate primarily underwater, as most have little function at the surface. Some submersibles operate on a "tether" or "umbilical", remaining connected to a tender (a submarine, surface vessel or platform). Submersibles have been able to dive to full ocean depth, over below the surface.
Submersibles may be relatively small, hold only a small crew, and have no living facilities.
A submersible often has very dexterous mobility, provided by marine thrusters or pump-jets.
Technologies
Technologies used in the design and construction of submersibles:
Buoyancy control
Marine thrusters
Pressure vessel with external pressure load
Life support systems
Through-water communications
Manipulator arm
Submarine navigation
Absolute pressure: At sea level the atmosphere exerts a pressure of approximately 1 bar, or 103,000 N/m2. Underwater, the pressure increases by approximately 0.1 bar for every metre of depth. The total pressure at any given depth is the sum of the pressure of the water at that depth (hydrostatic pressure)and atmospheric pressure. This combined pressure is known as absolute pressure, and the relationship is:
Absolute pressure (bar abs) = gauge pressure(bar) + atmospheric pressure (about 1 bar)
To calculate absolute pressure, add the atmospheric pressure to the gauge pressure using the same unit. Working with depth rather than pressure may be convenient in diving calculations. In this context, atmospheric pressure is considered equivalent to a depth of 10 meters.
Absolute depth (m) = gauge depth (m) + 10 m.
Depth measurement: Pressure monitoring devices
The pressure the is more important for structural and physiological reasons than linear depth. Pressure at a given depth may vary due to variations in water density.
To express the linear depth in water accurately, the measurement should be in meters (m). The unit “meters of sea water” (msw) is a by definition a unit for measurement of pressure.
Note: A change in depth of 10 meters for a change in pressure of 1 bar equates to a water density of 1012.72 kg/m3 | Submersible | Wikipedia | 485 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
Single-atmosphere submersibles have a pressure hull with internal pressure maintained at surface atmospheric pressure. This requires the hull to be capable of withstanding the ambient hydrostatic pressure from the water outside, which can be many times greater than the internal pressure.
Ambient pressure submersibles maintain the same pressure both inside and outside the vessel. The interior is air-filled, at a pressure to balance the external pressure, so the hull does not have to withstand a pressure difference.
A third technology is the "wet sub", which refers to a vehicle that may or may not be enclosed, but in either case, water floods the interior, so underwater breathing equipment is used by the crew. This may be scuba carried by the divers, or a breathing gas supply carried by the vessel.
Buoyancy
When an object is immersed in a liquid, it displaces the liquid, pushing it out of the way.
Once the object is partially immersed, pressure forces exerted on the immersed parts are equal to the weight of water displaced, Consequently, objects submerged in liquids appear to weigh less due to this buoyant force. The relationship between the amount of liquid displaced and the resulting up-thrust is known as Archimedes' principle, which states:
"when an object is wholly or partially immersed in a liquid, the up-thrust it receives is equal to the weight of the liquid displaced."
Buoyancy and weight determine whether an object floats or sinks in a liquid. The relative magnitudes of weight and buoyancy determine the outcome, leading to three possible scenarios.
Negative Buoyancy: when the weight of an object is greater than the up-thrust it experiences due to the weight of the liquid displaced, the object sinks.
Neutral Buoyancy: if the weight of an object equals the up-thrust, the object remains stable in its current position, neither sinking or floating.
Positive Buoyancy: when the weight of an object is less than the up-thrust, the object rises and floats. As it reaches the liquid's surface, It partly emerges from the liquid, reducing the weight of the displaced liquid and, consequently, the up-thrust. Eventually, the reduced up-thrust balances the weight of the object, allowing it to float in a state of equilibrium. | Submersible | Wikipedia | 465 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
Buoyancy control
During underwater operation a submersible will generally be neutrally buoyant, but may use positive or negative buoyancy to facilitate vertical motion. Negative buoyancy may also be useful at times to settle the vessel on the bottom, and positive buoyancy is necessary to float the vessel at the surface. Fine buoyancy adjustments may be made using one or more variable buoyancy pressure vessels as trim tanks, and gross changes of buoyancy at or near the surface may use ambient pressure ballast tanks, which are fully flooded during underwater operations. Some submersibles use high density external ballast which may be released at depth in an emergency to make the vessel sufficiently buoyant to float back to the surface even if all power is lost, or to travel faster vertically.
Deep-diving crewed submersibles
Some submersibles have been able to dive to great depths. The bathyscaphe Trieste was the first to reach the deepest part of the ocean, nearly below the surface, at the bottom of the Mariana Trench in 1960.
China, with its Jiaolong project in 2002, was the fifth country to send a person 3,500 meters below sea level, following the US, France, Russia and Japan. On June 22, 2012, the Jiaolong submersible set a deep-diving record for state-owned vessels when the three-person sub descended into the Pacific Ocean.
Among the most well-known and longest-in-operation submersibles is the deep-submergence research vessel , which takes 3 people to depths of up to . Alvin is owned by the United States Navy and operated by WHOI, and as of 2011 had made over 4,400 dives.
James Cameron made a record-setting, crewed submersible dive to the bottom of Challenger Deep, the deepest known point of the Mariana Trench on March 26, 2012. Cameron's submersible was named Deepsea Challenger and reached a depth of . | Submersible | Wikipedia | 406 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
DSV Limiting Factor, known as Bakunawa since its sale in 2022, is a crewed deep-submergence vehicle (DSV) manufactured by Triton Submarines and owned and operated since 2022 by Gabe Newell's Inkfish ocean-exploration research organization. It holds the records for the deepest crewed dives in all five oceans.
Limiting Factor was commissioned by Victor Vescovo for $37 million and operated by his marine research organization, Caladan Oceanic, between 2018-2022. It is commercially certified by DNV for dives to full ocean depth, and is operated by a pilot, with facilities for an observer.
The vessel was used in the Five Deeps Expedition, becoming the first crewed submersible to reach the deepest point in all five oceans. Over 21 people have visited Challenger Deep, the deepest area on Earth, in the DSV. Limiting Factor was used to identify the wrecks of the destroyers at a depth of , and at , in the Philippine Trench, the deepest dives on wrecks. It has also been used for dives to the French submarine Minerve (S647) at about in the Mediterranean sea, and at about in the Atlantic.
Commercial submersibles
Private firms such as Triton Submarines, LLC. SEAmagine Hydrospace, Sub Aviator Systems (or 'SAS'), and Netherlands-based U-boat Worx have developed small submersibles for tourism, exploration and adventure travel. A Canadian company in British Columbia called Sportsub has been building personal recreational submersibles since 1986 with open-floor designs (partially flooded cockpits).
A privately owned U.S. company, OceanGate, also participated in building submersibles, though the company fell under scrutiny when their newest submersible imploded underwater with no survivors.
Marine remotely operated vehicles
Small uncrewed submersibles called "marine remotely operated vehicles," (MROVs), or 'remotely operated underwater vehicles' (ROUVs) are widely used to work in water too deep or too dangerous for divers, or when it is economically advantageous. | Submersible | Wikipedia | 436 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
Remotely operated vehicles (ROVs) repair offshore oil platforms and attach cables to sunken ships to hoist them. Such remotely operated vehicles are attached by an umbilical cable (a thick cable providing power and communications) to a control center on a ship. Operators on the ship see video and/or sonar images sent back from the ROV and remotely control its thrusters and manipulator arm. The wreck of the Titanic was explored by such a vehicle, as well as by a crewed vessel.
Autonomous underwater vehicles
An autonomous underwater vehicle (AUV) is a robot that travels underwater without requiring continuous input from an operator. AUVs constitute part of a larger group of undersea systems known as unmanned underwater vehicles, a classification that includes non-autonomous remotely operated underwater vehicles (ROVs) – controlled and powered from the surface by an operator/pilot via an umbilical or using remote control. In military applications an AUV is more often referred to as an unmanned undersea vehicle (UUV). Underwater gliders are a subclass of AUVs.
Diver lock-out submersible
Class of submersible which has an airlock and an integral diving chamber from which underwater divers can be deployed, such as: | Submersible | Wikipedia | 249 | 575135 | https://en.wikipedia.org/wiki/Submersible | Technology | Naval transport | null |
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryptococcal meningitis, and others. Such drugs are usually obtained by a doctor's prescription, but a few are available over the counter (OTC). The evolution of antifungal resistance is a growing threat to health globally.
Routes of administration
Ocular
Indicated when the fungal infection is located in the eye. There is currently only one ocular antifungal available. This is Natamycin. However, various other antifungal agents could be compounded in this formulation.
Intrathecal
Used occasionally when there's an infection of the central nervous system and other systemic options cannot reach the concentration required in that region for therapeutic benefit. Example(s): amphotericin B.
Vaginal
This may be used to treat some fungal infections of the vaginal region. An example of a condition they are sometimes used for is candida vulvovaginitis which is treated with intravaginal Clotrimazole
Topical
This is sometimes indicated when there's a fungal infection on the skin. An example is tinea pedis; this is sometimes treated with topical terbinafine.
Oral
If the antifungal has good bioavailability, this is a common route to handle a fungal infection. An example is the use of ketoconazole to treat coccidioidomycosis.
Intravenous
Like the oral route, this will reach the bloodstream and distribute throughout the body. However, it is faster and a good option if the drug has poor bioavailability. An example of this is IV amphotericin B for the treatment of coccidioidomycosis.
Classes
The available classes of antifungal drugs are still limited but as of 2021 novel classes of antifungals are being developed and are undergoing various stages of clinical trials to assess performance.
Polyenes | Antifungal | Wikipedia | 434 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
A polyene is a molecule with multiple conjugated double bonds. A polyene antifungal is a macrocyclic polyene with a heavily hydroxylated region on the ring opposite the conjugated system. This makes polyene antifungals amphiphilic. The polyene antimycotics bind with sterols in the fungal cell membrane, principally ergosterol. This changes the transition temperature (Tg) of the cell membrane, thereby placing the membrane in a less fluid, more crystalline state. (In ordinary circumstances membrane sterols increase the packing of the phospholipid bilayer making the plasma membrane more dense.) As a result, the cell's contents including monovalent ions (K+, Na+, H+, and Cl−) and small organic molecules leak, which is regarded as one of the primary ways a cell dies. Animal cells contain cholesterol instead of ergosterol and so they are much less susceptible. However, at therapeutic doses, some amphotericin B may bind to animal membrane cholesterol, increasing the risk of human toxicity. Amphotericin B is nephrotoxic when given intravenously. As a polyene's hydrophobic chain is shortened, its sterol binding activity is increased. Therefore, further reduction of the hydrophobic chain may result in it binding to cholesterol, making it toxic to animals.
Amphotericin B
Candicidin
Filipin – 35 carbons, binds to cholesterol (toxic)
Hamycin
Natamycin – 33 carbons, binds well to ergosterol
Nystatin
Rimocidin
Azoles
Azole antifungals inhibit the conversion of lanosterol to ergosterol by inhibiting lanosterol 14α-demethylase. These compounds have a five-membered ring containing two or three nitrogen atoms. The imidazole antifungals contain a 1,3-diazole (imidazole) ring (two nitrogen atoms), whereas the triazole antifungals have a ring with three nitrogen atoms.
Imidazoles
Bifonazole
Butoconazole
Clotrimazole
Econazole
Fenticonazole
Isoconazole
Ketoconazole
Luliconazole
Miconazole
Omoconazole
Oxiconazole
Sertaconazole
Sulconazole
Tioconazole
Triazoles | Antifungal | Wikipedia | 510 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
Albaconazole
Cyproconazole
Efinaconazole
Epoxiconazole
Fluconazole
Isavuconazole
Itraconazole
Posaconazole
Propiconazole
Ravuconazole
Terconazole
Voriconazole
Thiazoles
Abafungin
Allylamines
Allylamines inhibit squalene epoxidase, another enzyme required for ergosterol synthesis. Examples include butenafine, naftifine, and terbinafine.
Echinocandins
Echinocandins inhibit the creation of glucan in the fungal cell wall by inhibiting 1,3-Beta-glucan synthase:
Anidulafungin
Caspofungin
Micafungin
Echinocandins are administered intravenously, particularly for the treatment of resistant Candida species.
Triterpenoids
Ibrexafungerp | Antifungal | Wikipedia | 188 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
Others
Acrisorcin
Amorolfine – a morpholine derivative used topically in dermatophytosis
Aurones – possess antifungal properties
Benzoic acid – has antifungal properties, such as in Whitfield's ointment, Friar's Balsam, and Balsam of Peru
Carbol fuchsin (Castellani's paint)
Ciclopirox (ciclopirox olamine) – a hydroxypyridone antifungal that interferes with active membrane transport, cell membrane integrity, and fungal respiratory processes. It is most useful against tinea versicolour.
Clioquinol
Coal tar
Copper(II) sulfate
Crystal violet – a triarylmethane dye. It has antibacterial, antifungal, and anthelmintic properties and was formerly important as a topical antiseptic.
Chlorhexidine is a topical antibacterial and antifungal. It is commonly used in hospitals as an antiseptic. It is much more strongly antibacterial than antifungal, requiring at least a 10 times higher concentration to kill yeast compared to gram negative bacteria
Chlorophetanol
Diiodohydroxyquinoline (Iodoquinol)
Flucytosine (5-fluorocytosine) – an antimetabolite pyrimidine analog
Fumagillin
Griseofulvin – binds to microtubules and inhibits mitosis
Haloprogin – discontinued due to the emergence of antifungals with fewer side effects
Miltefosine works by damaging fungal cell membranes
Nikkomycin – blocks formation of chitin present in the cell wall of fungus.
Orotomide (F901318) – pyrimidine synthesis inhibitor
Piroctone olamine
Pentanenitrile
Potassium iodide – preferred treatment for lymphocutaneous sporotrichosis and subcutaneous zygomycosis (basidiobolomycosis). The mode of action is obscure.
Potassium permanganate - for use only on thicker, more insensitive skin such as the soles of the feet.
Selenium disulfide
Sodium thiosulfate
Sulfur
Tolnaftate – a thiocarbamate antifungal, which inhibits fungal squalene epoxidase (similar mechanism to allylamines like terbinafine) | Antifungal | Wikipedia | 511 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
Triacetin – hydrolysed to acetic acid by fungal esterases
Undecylenic acid – an unsaturated fatty acid derived from natural castor oil; fungistatic, antibacterial, antiviral, and inhibits Candida morphogenesis
Zinc pyrithione | Antifungal | Wikipedia | 63 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
Side effects
Incidents of liver injury or failure among modern antifungal medicines are very low to non-existent. However, some can cause allergic reactions in people.
There are also many drug interactions. Patients must read in detail the enclosed data sheet(s) of any medicine. For example, the azole antifungals such as ketoconazole or itraconazole can be both substrates and inhibitors of the P-glycoprotein, which (among other functions) excretes toxins and drugs into the intestines. Azole antifungals are also both substrates and inhibitors of the cytochrome P450 family CYP3A4, causing increased concentration when administering, for example, calcium channel blockers, immunosuppressants, chemotherapeutic drugs, benzodiazepines, tricyclic antidepressants, macrolides and SSRIs.
Before oral antifungal therapies are used to treat nail disease, a confirmation of the fungal infection should be made. Approximately half of suspected cases of fungal infection in nails have a non-fungal cause. The side effects of oral treatment are significant and people without an infection should not take these drugs.
Azoles are the group of antifungals which act on the cell membrane of fungi. They inhibit the enzyme 14-alpha-sterol demethylase, a microsomal CYP, which is required for the biosynthesis of ergosterol for the cytoplasmic membrane. This leads to the accumulation of 14-alpha-methylsterols resulting in impairment of function of certain membrane-bound enzymes and disruption of close packing of acyl chains of phospholipids, thus inhibiting growth of the fungi. Some azoles directly increase permeability of the fungal cell membrane.
Resistance
Antifungal resistance is a subset of antimicrobial resistance, that specifically applies to fungi that have become resistant to antifungals. Resistance to antifungals can arise naturally, for example by genetic mutation or through aneuploidy. Extended use of antifungals leads to the development of antifungal resistance through various mechanisms. | Antifungal | Wikipedia | 455 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
Some fungi (e.g. Candida krusei and fluconazole) exhibit intrinsic resistance to certain antifungal drugs or classes, whereas some species develop antifungal resistance to external pressures. Antifungal resistance is a One Health concern, driven by multiple extrinsic factors, including extensive fungicidal use, overuse of clinical antifungals, environmental change and host factors.
Like resistance to antibacterials, antifungal resistance can be driven by antifungal use in agriculture. Currently there is no regulation on the use of similar antifungal classes in agriculture and the clinic.
The emergence of Candida auris as a potential human pathogen that sometimes exhibits multi-class antifungal drug resistance is concerning and has been associated with several outbreaks globally. The WHO has released a priority fungal pathogen list, including pathogens with antifungal resistance. | Antifungal | Wikipedia | 188 | 575176 | https://en.wikipedia.org/wiki/Antifungal | Biology and health sciences | Antifungals | Health |
A hide or skin is an animal skin treated for human use.
The word "hide" is related to the German word , which means skin. The industry defines hides as "skins" of large animals e.g. cow, buffalo; while skins refer to "skins" of smaller animals: goat, sheep, deer, pig, fish, alligator, snake, etc.
Common commercial hides include leather from cattle and other livestock animals, buckskin, alligator skin and snake skin. All are used for shoes, clothes, leather bags, belts, or other fashion accessories. Leather is also used in cars, upholstery, interior decorating, horse tack and harnesses. Skins are sometimes still gathered from hunting and processed at a domestic or artisanal level but most leather making is now industrialized and large-scale. Various tannins are used for this purpose. Hides are also used as processed chews for dogs or other pets.
The term "skin" is sometimes expanded to include furs, which are harvested from various species, including cats, mustelids, and bears.
History
Archaeologists believe that animal hides provided an important source of clothing and shelter for all prehistoric humans and their use continued among non-agricultural societies into modern times. The Inuit, for example, used animal hides for summer tents, waterproof clothes, and kayaks. In early medieval ages hides were used to protect wooden castles and defense buildings from setting alight during a siege. Various American Indian tribes used hides in the construction of tepees and wigwams, moccasins, and buckskins. They were sometimes used as window coverings. Until the invention of plastic drum heads in the 1950s, animal hides or metal was used.
Parchment and vellum—a kind of paper made from processed skins—was introduced to the Eastern Mediterranean during the Iron Age, supposedly at Pergamon.
The Assize of Weights and Measures—one of the statutes of uncertain date from —mentions rawhide, gloves, parchment, and vellum among the principal items of England's commerce. A standardized shipload of leather (a last) consisted of 20 dicker of 10 cowhides. Rabbit and squirrel skins were traded and taxed in timbers of 40 hides each. Skins were also traded in binds of 32 or 33 skins each, while gloves were sold in dickers of 10 pair and dozens of 12 pair. The parchment and vellum was traded based on dozens of the original sheepskins from which they were prepared. | Hide (skin) | Wikipedia | 505 | 575495 | https://en.wikipedia.org/wiki/Hide%20%28skin%29 | Technology | Materials | null |
Rare furs have been a notable status symbol throughout history. Ermine fur was particularly associated with European nobility, with the black-tipped tails arranged around the edges of the robes to produce a pattern of black diamonds on a white field. Demand for beaver hats in the 17th and 18th century drove some of the initial exploration of North America, particularly in Canada, and even prompted wars among native tribes competing for the most productive areas. Natural leather continues to be used for many expensive products from limousine upholstery to designer cellular phone cases. There are, however, many forms of artificial leather and fur now available, which are usually cheaper alternatives.
Production
Animal hides and skins are usually processed fresh or salted and tanned. Skins sometimes are stretched, dried, and tanned. Most hides are processed from domesticated animals; the most common wild animals used for fur—mink and rabbit—are similarly raised in captivity and farmed. Some others—including lynx and wolves—are still trapped in the wild for their fur.
Use
Currently, hides are mainly used for footwear, upholstery, leather goods; skins are used for clothing, particularly as coats, gloves, leather goods and footwear. It is also used for bookbinding.
Many traditional drums, especially hand drums like the pandeiro, continue to be made using natural skins. The alligator drum was formerly important in Chinese music. The Chinese sanxian and Okinawan sanshin are usually prepared from snakeskin, while their Japanese equivalent, the shamisen, is made from dogskin in the case of students and catskin in the case of professional players. The African-American banjo was originally made from skins but is now often synthetic. "Hides" is used as a slang term to refer to a drumset.
Kangaroo leather is the most common material for the construction of bullwhips. Stingray rawhide is a common material for the grips of Chinese, Japanese, and Scottish swords.
Pig skins are processed as pork rinds.
Rabbit fur is popular for hats, coats, and glove linings. | Hide (skin) | Wikipedia | 416 | 575495 | https://en.wikipedia.org/wiki/Hide%20%28skin%29 | Technology | Materials | null |
Controversy
Animal rights activists generally protest the use of animal hides for human clothing. Forms of protest range from PETA's "I would rather go naked than wear fur" campaign, although more shocking and direct action, like damaging furs with red paint in imitation of blood, has been toned down, like the "Ink, not Mink" campaign.
Roadblocking and break-ins against meat/fur/leather industry is also used and extends to personal campaigns against such companies and also hunters which have included arson and assault in some cases. | Hide (skin) | Wikipedia | 109 | 575495 | https://en.wikipedia.org/wiki/Hide%20%28skin%29 | Technology | Materials | null |
The deltoid muscle is the muscle forming the rounded contour of the human shoulder. It is also known as the 'common shoulder muscle', particularly in other animals such as the domestic cat. Anatomically, the deltoid muscle is made up of three distinct sets of muscle fibers, namely the
anterior or clavicular part (pars clavicularis)
posterior or scapular part (pars scapularis)
intermediate or acromial part (pars acromialis)
The deltoid's fibres are Pennate muscle.
However, electromyography suggests that it consists of at least seven groups that can be independently coordinated by the nervous system.
It was previously called the deltoideus (plural deltoidei) and the name is still used by some anatomists. It is called so because it is in the shape of the Greek capital letter delta (Δ). Deltoid is also further shortened in slang as "delt".
A study of 30 shoulders revealed an average mass of in humans, ranging from to .
Structure
Origin
The anterior or clavicular fibers arise from most of the anterior border and upper surface of the lateral third of the clavicle. The anterior origin lies adjacent to the lateral fibers of the pectoralis major muscle as do the end tendons of both muscles. These muscle fibers are closely related and only a small chiasmatic space, through which the cephalic vein passes, prevents the two muscles from forming a continuous muscle mass.
Intermediate or acromial fibers arise from the superior surface of the acromion process of the scapula.
Posterior or spinal fibers arise from the lower lip of the posterior border of the spine of the scapula.
Insertion
From this extensive origin the fibers converge toward their insertion on the deltoid tuberosity on the middle of the lateral aspect of the shaft of the humerus; the intermediate fibers passing vertically, the anterior obliquely backward and laterally, and the posterior obliquely forward and laterally. | Deltoid muscle | Wikipedia | 414 | 575531 | https://en.wikipedia.org/wiki/Deltoid%20muscle | Biology and health sciences | Human anatomy | Health |
Though traditionally described as a single insertion, the deltoid insertion is divided into two or three discernible areas corresponding to the muscle's three areas of origin. The insertion is an arch-like structure with strong anterior and posterior fascial connections flanking an intervening tissue bridge. It additionally gives off extensions to the deep brachial fascia. Furthermore, the deltoid fascia contributes to the brachial fascia and is connected to the medial and lateral intermuscular septa.
Blood supply
The deltoid is supplied by the thoracoacromial artery (acromial and deltoid branches), the circumflex humeral arteries, and the profunda brachii artery (deltoid branch).
Nerve supply
The deltoid is innervated by the axillary nerve. The axillary nerve originates from the anterior rami of the cervical nerves C5 and C6, via the superior trunk, posterior division of the superior trunk, and the posterior cord of the brachial plexus.
Studies have shown that there are seven neuromuscular segments to the deltoid muscle. Three of these lie in the anatomical anterior head of the deltoid, one in the anatomical middle head, and three in the anatomical posterior head of the deltoid. These neuromuscular segments are supplied by smaller branches of the axillary nerve, and work in coordination with other muscles of the shoulder girdle include pectoralis major and supraspinatus.
The axillary nerve is sometimes damaged during surgical procedures of the axilla, such as for breast cancer. It may also be injured by anterior dislocation of the head of the humerus.
Structures under deltoid
Humerus
Pectoralis minor
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Pectoralis major
Teres major
Latissimus dorsi coracobrachialis
Biceps brachii
Triceps brachii
Anterior circumflex humeral vessels
Posterior circumflex humeral vessels
Axillary nerve
Shoulder joint
Rotator cuff
Coracoacromial ligament
Function | Deltoid muscle | Wikipedia | 445 | 575531 | https://en.wikipedia.org/wiki/Deltoid%20muscle | Biology and health sciences | Human anatomy | Health |
When all its fibers contract simultaneously, the deltoid is the prime mover of arm abduction along the frontal plane. The arm must be medially rotated for the deltoid to have maximum effect. This makes the deltoid an antagonist muscle of the pectoralis major and latissimus dorsi during arm adduction. The anterior fibers assist the pectoralis major to flex the shoulder. The anterior deltoid also works in tandem with the subscapularis, pecs and lats to internally (medially) rotate the humerus. The intermediate fibers perform basic shoulder abduction when the shoulder is internally rotated, and perform shoulder transverse abduction when the shoulder is externally rotated. They are not utilized significantly during strict transverse extension (shoulder internally rotated) such as in rowing movements, which use the posterior fibers. The posterior fibers assist the latissimus dorsi to extend the shoulder. Other transverse extensors, the infraspinatus and teres minor, also work in tandem with the posterior deltoid as external (lateral) rotators, antagonists to strong internal rotators like the pecs and lats.
An important function of the deltoid in humans is preventing the dislocation of the humeral head when a person carries heavy loads. The function of abduction also means that it would help keep carried objects a safer distance away from the thighs to avoid hitting them, as during a farmer's walk. It also ensures a precise and rapid movement of the glenohumeral joint needed for hand and arm manipulation. The intermediate fibers are in the most efficient position to perform this role, though like basic abduction movements (such as lateral raise) it is assisted by simultaneous co-contraction of anterior/posterior fibers.
The deltoid is responsible for elevating the arm in the scapular plane and its contraction in doing this also elevates the humeral head. To stop this compressing against the undersurface of the acromion the humeral head and injuring the supraspinatus tendon, there is a simultaneous contraction of some of the muscles of the rotator cuff: the infraspinatus and subscapularis primarily perform this role. In spite of this there may be still a 1–3 mm upward movement of the head of the humerus during the first 30° to 60° of arm elevation. | Deltoid muscle | Wikipedia | 488 | 575531 | https://en.wikipedia.org/wiki/Deltoid%20muscle | Biology and health sciences | Human anatomy | Health |
Clinical significance
The most common abnormalities affecting the deltoid are tears, fatty atrophy, and enthesopathy. Deltoid muscle tears are unusual and frequently related to traumatic shoulder dislocation or massive rotator cuff tears. Muscle atrophy may result from various causes, including aging, disuse, denervation, muscular dystrophy, cachexia and iatrogenic injury. Deltoidal humeral enthesopathy is an exceedingly rare condition related to mechanical stress. Conversely, deltoideal acromial enthesopathy is likely a hallmark of seronegative spondylarthropathies and its detection should probably be followed by pertinent clinical and serological investigation.
The Deltoid Muscle is tested by asking the patient to abduct the arm against resistance applied with one hand, and feeling for the contracting muscle with the other hand.
Site of the intramuscular injection in deltoid: The intramuscular injections are commonly given in the lower half of the deltoid to avoid injury to the axillary nerve, which winds around the surgical neck of the humerus.
Other animals
The deltoid is also found in members of the great ape family other than humans. The human deltoid is of similar proportionate size as the muscles of the rotator cuff in apes like the orangutan, which engage in brachiation and possess the muscle mass needed to support the body weight by the shoulders. In other apes, like the common chimpanzee, the deltoid is much larger than in humans, weighing an average of 383.3 gram compared to 191.9 gram in humans. This reflects the need to strengthen the shoulders, particularly the rotatory cuff, in knuckle walking apes for the purpose of supporting the entire body weight.
The deltoid muscle is a main component of both the bat and pterosaur wing musculature, but in crown-group birds it is strongly reduced, as they favour sternum attached muscles. Some Mesozoic flying theropods, however, had more developed deltoideus. | Deltoid muscle | Wikipedia | 437 | 575531 | https://en.wikipedia.org/wiki/Deltoid%20muscle | Biology and health sciences | Human anatomy | Health |
Navy blue is a dark shade of the color blue.
Navy blue got its name from the dark blue (contrasted with naval white) worn by officers in the Royal Navy since 1748 and subsequently adopted by other navies around the world. When this color name, taken from the usual color of the uniforms of sailors, originally came into use in the early 19th century, it was initially called marine blue, but the name of the color soon changed to navy blue.
An early use of navy blue as a color name in English was in 1840 though the Oxford English Dictionary has a citation from 1813.
Variations
Indigo dye
Indigo dye is the color that is called Añil (the Spanish word for "indigo dye") in the Guía de coloraciones (Guide to colorations) by Rosa Gallego and Juan Carlos Sanz, a color dictionary published in 2005 that is widely popular in the Hispanophone realm.
Indigo dye is the basis for all the historical navy blue colors, since in the 18th, 19th, and early 20th century, almost all navy uniforms were made by dyeing them with various shades of indigo dye.
Navy blue (Crayola)
The Crayola color named "navy blue" is not as dark a shade as the blues actually used by navies.
This tone of navy blue was formulated as a Crayola color in 1958.
Peacoat
The source of this color is the Pantone textile cotton extended color list, color #19-3920 TCX—peacoat.
Persian indigo
The color Persian indigo is displayed at right. Another name for this color is regimental because in the 19th century it was commonly used by many nations for navy uniforms, though it is seldom used in modern times.
Persian indigo is named for an association with a product from Persia: Persian cloth dyed with indigo.
The first recorded use of regimental (the original name for the color now called Persian indigo) as a color name in English was in 1912.
Space cadet
Space cadet is one of the colors on the Resene Color List, a color list widely popular in Australia and New Zealand. The color was formulated in 2007.
This color is apparently a formulation of an impression of the color that cadets in space navy training would wear.
In culture
Computers
The color navy was one of the original 16 HTML/CSS colors initially formulated for standardized computer display in the late 1980s. | Navy blue | Wikipedia | 473 | 575590 | https://en.wikipedia.org/wiki/Navy%20blue | Physical sciences | Colors | Physics |
Military
In many world navies, including the United States Navy and the Royal Canadian Navy, uniforms which are called "navy blue" are, in actuality, colored black, as the uniforms became progressively darker over time to counter fading of the dye, though for modern dyes are fade resistant. The Canadian Forces dress instructions specify that navy blue' is a tone of black". (See also uniforms of the United States Navy and uniforms of the Canadian Forces.)
Music
Navy Blue is an album by Diane Renay (all the songs are about sailors).
Sports
Navy blue is used by numerous professional and collegiate sports teams:
Association football
Scottish national team
United States men's and women's national teams
Falkirk F.C.
Manchester City F.C.
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University of Connecticut | Navy blue | Wikipedia | 479 | 575590 | https://en.wikipedia.org/wiki/Navy%20blue | Physical sciences | Colors | Physics |
There are 95 moons of Jupiter with confirmed orbits . This number does not include a number of meter-sized moonlets thought to be shed from the inner moons, nor hundreds of possible kilometer-sized outer irregular moons that were only briefly captured by telescopes. All together, Jupiter's moons form a satellite system called the Jovian system. The most massive of the moons are the four Galilean moons: Io, Europa, Ganymede, and Callisto, which were independently discovered in 1610 by Galileo Galilei and Simon Marius and were the first objects found to orbit a body that was neither Earth nor the Sun. Much more recently, beginning in 1892, dozens of far smaller Jovian moons have been detected and have received the names of lovers (or other sexual partners) or daughters of the Roman god Jupiter or his Greek equivalent Zeus. The Galilean moons are by far the largest and most massive objects to orbit Jupiter, with the remaining 91 known moons and the rings together comprising just 0.003% of the total orbiting mass.
Of Jupiter's moons, eight are regular satellites with prograde and nearly circular orbits that are not greatly inclined with respect to Jupiter's equatorial plane. The Galilean satellites are nearly spherical in shape due to their planetary mass, and are just massive enough that they would be considered major planets if they were in direct orbit around the Sun. The other four regular satellites, known as the inner moons, are much smaller and closer to Jupiter; these serve as sources of the dust that makes up Jupiter's rings. The remainder of Jupiter's moons are outer irregular satellites whose prograde and retrograde orbits are much farther from Jupiter and have high inclinations and eccentricities. The largest of these moons were likely asteroids that were captured from solar orbits by Jupiter before impacts with other small bodies shattered them into many kilometer-sized fragments, forming collisional families of moons sharing similar orbits. Jupiter is expected to have about 100 irregular moons larger than in diameter, plus around 500 more smaller retrograde moons down to diameters of . Of the 87 known irregular moons of Jupiter, 38 of them have not yet been officially given names.
Characteristics | Moons of Jupiter | Wikipedia | 436 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The physical and orbital characteristics of the moons vary widely. The four Galileans are all over in diameter; the largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets, Ganymede being larger than Mercury. All other Jovian moons are less than in diameter, with most barely exceeding . Their orbital shapes range from nearly perfectly circular to highly eccentric and inclined, and many revolve in the direction opposite to Jupiter's rotation (retrograde motion).
Origin and evolution
Jupiter's regular satellites are believed to have formed from a circumplanetary disk, a ring of accreting gas and solid debris analogous to a protoplanetary disk. They may be the remnants of a score of Galilean-mass satellites that formed early in Jupiter's history.
Simulations suggest that, while the disk had a relatively high mass at any given moment, over time a substantial fraction (several tens of a percent) of the mass of Jupiter captured from the solar nebula was passed through it. However, only 2% of the proto-disk mass of Jupiter is required to explain the existing satellites. Thus, several generations of Galilean-mass satellites may have been in Jupiter's early history. Each generation of moons might have spiraled into Jupiter, because of drag from the disk, with new moons then forming from the new debris captured from the solar nebula. By the time the present (possibly fifth) generation formed, the disk had thinned so that it no longer greatly interfered with the moons' orbits. The current Galilean moons were still affected, falling into and being partially protected by an orbital resonance with each other, which still exists for Io, Europa, and Ganymede: they are in a 1:2:4 resonance. Ganymede's larger mass means that it would have migrated inward at a faster rate than Europa or Io. Tidal dissipation in the Jovian system is still ongoing and Callisto will likely be captured into the resonance in about 1.5 billion years, creating a 1:2:4:8 chain.
The outer, irregular moons are thought to have originated from captured asteroids, whereas the protolunar disk was still massive enough to absorb much of their momentum and thus capture them into orbit. Many are believed to have been broken up by mechanical stresses during capture, or afterward by collisions with other small bodies, producing the moons we see today.
History and discovery
Visual observations | Moons of Jupiter | Wikipedia | 507 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Chinese historian Xi Zezong claimed that the earliest record of a Jovian moon (Ganymede or Callisto) was a note by Chinese astronomer Gan De of an observation around 364 BC regarding a "reddish star". However, the first certain observations of Jupiter's satellites were those of Galileo Galilei in 1609. By January 1610, he had sighted the four massive Galilean moons with his 20× magnification telescope, and he published his results in March 1610.
Simon Marius had independently discovered the moons one day after Galileo, although he did not publish his book on the subject until 1614. Even so, the names Marius assigned are used today: Ganymede, Callisto, Io, and Europa. No additional satellites were discovered until E. E. Barnard observed Amalthea in 1892.
Photographic and spacecraft observations
With the aid of telescopic photography with photographic plates, further discoveries followed quickly over the course of the 20th century. Himalia was discovered in 1904, Elara in 1905, Pasiphae in 1908, Sinope in 1914, Lysithea and Carme in 1938, Ananke in 1951, and Leda in 1974.
By the time that the Voyager space probes reached Jupiter, around 1979, thirteen moons had been discovered, not including Themisto, which had been observed in 1975, but was lost until 2000 due to insufficient initial observation data. The Voyager spacecraft discovered an additional three inner moons in 1979: Metis, Adrastea, and Thebe.
Digital telescopic observations
No additional moons were discovered until two decades later, with the fortuitous discovery of Callirrhoe by the Spacewatch survey in October 1999. During the 1990s, photographic plates phased out as digital charge-coupled device (CCD) cameras began emerging in telescopes on Earth, allowing for wide-field surveys of the sky at unprecedented sensitivities and ushering in a wave of new moon discoveries. Scott Sheppard, then a graduate student of David Jewitt, demonstrated this extended capability of CCD cameras in a survey conducted with the Mauna Kea Observatory's UH88 telescope in November 2000, discovering eleven new irregular moons of Jupiter including the previously lost Themisto with the aid of automated computer algorithms. | Moons of Jupiter | Wikipedia | 454 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
From 2001 onward, Sheppard and Jewitt alongside other collaborators continued surveying for Jovian irregular moons with the Canada-France-Hawaii Telescope (CFHT), discovering an additional eleven in December 2001, one in October 2002, and nineteen in February 2003. At the same time, another independent team led by Brett J. Gladman also used the CFHT in 2003 to search for Jovian irregular moons, discovering four and co-discovering two with Sheppard. From the start to end of these CCD-based surveys in 2000–2004, Jupiter's known moon count had grown from 17 to 63. All of these moons discovered after 2000 are faint and tiny, with apparent magnitudes between 22–23 and diameters less than . As a result, many could not be reliably tracked and ended up becoming lost.
Beginning in 2009, a team of astronomers, namely Mike Alexandersen, Marina Brozović, Brett Gladman, Robert Jacobson, and Christian Veillet, began a campaign to recover Jupiter's lost irregular moons using the CFHT and Palomar Observatory's Hale Telescope. They discovered two previously unknown Jovian irregular moons during recovery efforts in September 2010, prompting further follow-up observations to confirm these by 2011. One of these moons, S/2010 J 2 (now Jupiter LII), has an apparent magnitude of 24 and a diameter of only , making it one of the faintest and smallest confirmed moons of Jupiter even . Meanwhile, in September 2011, Scott Sheppard, now a faculty member of the Carnegie Institution for Science, discovered two more irregular moons using the institution's Magellan Telescopes at Las Campanas Observatory, raising Jupiter's known moon count to 67. Although Sheppard's two moons were followed up and confirmed by 2012, both became lost due to insufficient observational coverage. | Moons of Jupiter | Wikipedia | 366 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
In 2016, while surveying for distant trans-Neptunian objects with the Magellan Telescopes, Sheppard serendipitously observed a region of the sky located near Jupiter, enticing him to search for Jovian irregular moons as a detour. In collaboration with Chadwick Trujillo and David Tholen, Sheppard continued surveying around Jupiter from 2016 to 2018 using the Cerro Tololo Observatory's Víctor M. Blanco Telescope and Mauna Kea Observatory's Subaru Telescope. In the process, Sheppard's team recovered several lost moons of Jupiter from 2003 to 2011 and reported two new Jovian irregular moons in June 2017. Then in July 2018, Sheppard's team announced ten more irregular moons confirmed from 2016 to 2018 observations, bringing Jupiter's known moon count to 79. Among these was Valetudo, which has an unusually distant prograde orbit that crosses paths with the retrograde irregular moons. Several more unidentified Jovian irregular satellites were detected in Sheppard's 2016–2018 search, but were too faint for follow-up confirmation.
From November 2021 to January 2023, Sheppard discovered twelve more irregular moons of Jupiter and confirmed them in archival survey imagery from 2003 to 2018, bringing the total count to 92. Among these was S/2018 J 4, a highly inclined prograde moon that is now known to be in same orbital grouping as the moon Carpo, which was previously thought to be solitary. On 22 February 2023, Sheppard announced three more moons discovered in a 2022 survey, now bringing Jupiter's total known moon count to 95. In a February 2023 interview with NPR, Sheppard noted that he and his team are currently tracking even more moons of Jupiter, which should place Jupiter's moon count over 100 once confirmed over the next two years. | Moons of Jupiter | Wikipedia | 361 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Many more irregular moons of Jupiter will inevitably be discovered in the future, especially after the beginning of deep sky surveys by the upcoming Vera C. Rubin Observatory and Nancy Grace Roman Space Telescope in the mid-2020s. The Rubin Observatory's aperture telescope and 3.5 square-degree field of view will probe Jupiter's irregular moons down to diameters of at apparent magnitudes of 24.5, with the potential of increasing the known population by up to tenfold. Likewise, the Roman Space Telescope's aperture and 0.28 square-degree field of view will probe Jupiter's irregular moons down to diameters of at magnitude 27.7, with the potential of discovering approximately 1,000 Jovian moons above this size. Discovering these many irregular satellites will help reveal their population's size distribution and collisional histories, which will place further constraints to how the Solar System formed.
Naming
The Galilean moons of Jupiter (Io, Europa, Ganymede, and Callisto) were named by Simon Marius soon after their discovery in 1610. However, these names fell out of favor until the 20th century. The astronomical literature instead simply referred to "Jupiter I", "Jupiter II", etc., or "the first satellite of Jupiter", "Jupiter's second satellite", and so on. The names Io, Europa, Ganymede, and Callisto became popular in the mid-20th century, whereas the rest of the moons remained unnamed and were usually numbered in Roman numerals V (5) to XII (12). Jupiter V was discovered in 1892 and given the name Amalthea by a popular though unofficial convention, a name first used by French astronomer Camille Flammarion. | Moons of Jupiter | Wikipedia | 348 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The other moons were simply labeled by their Roman numeral (e.g. Jupiter IX) in the majority of astronomical literature until the 1970s. Several different suggestions were made for names of Jupiter's outer satellites, but none were universally accepted until 1975 when the International Astronomical Union's (IAU) Task Group for Outer Solar System Nomenclature granted names to satellites V–XIII, and provided for a formal naming process for future satellites still to be discovered. The practice was to name newly discovered moons of Jupiter after lovers and favorites of the god Jupiter (Zeus) and, since 2004, also after their descendants. All of Jupiter's satellites from XXXIV (Euporie) onward are named after descendants of Jupiter or Zeus, except LIII (Dia), named after a lover of Jupiter. Names ending with "a" or "o" are used for prograde irregular satellites (the latter for highly inclined satellites), and names ending with "e" are used for retrograde irregulars. With the discovery of smaller, kilometre-sized moons around Jupiter, the IAU has established an additional convention to limit the naming of small moons with absolute magnitudes greater than 18 or diameters smaller than . Some of the most recently confirmed moons have not received names.
Some asteroids share the same names as moons of Jupiter: 9 Metis, 38 Leda, 52 Europa, 85 Io, 113 Amalthea, 239 Adrastea. Two more asteroids previously shared the names of Jovian moons until spelling differences were made permanent by the IAU: Ganymede and asteroid 1036 Ganymed; and Callisto and asteroid 204 Kallisto.
Groups | Moons of Jupiter | Wikipedia | 333 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Regular satellites
These have prograde and nearly circular orbits of low inclination and are split into two groups:
Inner satellites or Amalthea group: Metis, Adrastea, Amalthea, and Thebe. These orbit very close to Jupiter; the innermost two orbit in less than a Jovian day. The latter two are respectively the fifth and seventh largest moons in the Jovian system. Observations suggest that at least the largest member, Amalthea, did not form on its present orbit, but farther from the planet, or that it is a captured Solar System body. These moons, along with a number of seen and as-yet-unseen inner moonlets (see Amalthea moonlets), replenish and maintain Jupiter's faint ring system. Metis and Adrastea help to maintain Jupiter's main ring, whereas Amalthea and Thebe each maintain their own faint outer rings.
Main group or Galilean moons: Io, Europa, Ganymede and Callisto. They are some of the largest objects in the Solar System outside the Sun and the eight planets in terms of mass, larger than any known dwarf planet. Ganymede exceeds (and Callisto nearly equals) even the planet Mercury in diameter, though they are less massive. They are respectively the fourth-, sixth-, first-, and third-largest natural satellites in the Solar System, containing approximately 99.997% of the total mass in orbit around Jupiter, while Jupiter is almost 5,000 times more massive than the Galilean moons. The inner moons are in a 1:2:4 orbital resonance. Models suggest that they formed by slow accretion in the low-density Jovian subnebula—a disc of the gas and dust that existed around Jupiter after its formation—which lasted up to 10 million years in the case of Callisto. Europa, Ganymede, and Callisto are suspected of having subsurface water oceans, and Io may have a subsurface magma ocean.
Irregular satellites | Moons of Jupiter | Wikipedia | 410 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The irregular satellites are substantially smaller objects with more distant and eccentric orbits. They form families with shared similarities in orbit (semi-major axis, inclination, eccentricity) and composition; it is believed that these are at least partially collisional families that were created when larger (but still small) parent bodies were shattered by impacts from asteroids captured by Jupiter's gravitational field. These families bear the names of their largest members. The identification of satellite families is tentative, but the following are typically listed:
Prograde satellites:
Themisto is the innermost irregular moon and is not part of a known family.
The Himalia group is confined within semi-major axes between , inclinations between 27 and 29°, and eccentricities between 0.12 and 0.21. It has been suggested that the group could be a remnant of the break-up of an asteroid from the asteroid belt. The largest two members, Himalia and Elara, are respectively the sixth- and eighth-largest Jovian moons.
The Carpo group includes two known moons on very high orbital inclinations of 50° and semi-major axes between . Due to their exceptionally high inclinations, the moons of the Carpo group are subject to gravitational perturbations that induce the Lidov–Kozai resonance in their orbits, which cause their eccentricities and inclinations to periodically oscillate in correspondence with each other. The Lidov–Kozai resonance can significantly alter the orbits of these moons: for example, the eccentricity and inclination of the group's namesake Carpo can fluctuate between 0.19–0.69 and 44–59°, respectively.
Valetudo is the outermost prograde moon and is not part of a known family. Its prograde orbit crosses paths with several moons that have retrograde orbits and may in the future collide with them.
Retrograde satellites:
The Carme group is tightly confined within semi-major axes between , inclinations between 164 and 166°, and eccentricities between 0.25 and 0.28. It is very homogeneous in color (light red) and is believed to have originated as collisional fragments from a D-type asteroid progenitor, possibly a Jupiter trojan.
The Ananke group has a relatively wider spread than the previous groups, with semi-major axes between , inclinations between 144 and 156°, and eccentricities between 0.09 and 0.25. Most of the members appear gray, and are believed to have formed from the breakup of a captured asteroid. | Moons of Jupiter | Wikipedia | 512 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
The Pasiphae group is quite dispersed, with semi-major axes spread over , inclinations between 141° and 157°, and higher eccentricities between 0.23 and 0.44. The colors also vary significantly, from red to grey, which might be the result of multiple collisions. Sinope, sometimes included in the Pasiphae group, is red and, given the difference in inclination, it could have been captured independently; Pasiphae and Sinope are also trapped in secular resonances with Jupiter. | Moons of Jupiter | Wikipedia | 104 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Based on their survey discoveries in 2000–2003, Sheppard and Jewitt predicted that Jupiter should have approximately 100 irregular satellites larger than in diameter, or brighter than magnitude 24. Survey observations by Alexandersen et al. in 2010–2011 agreed with this prediction, estimating that approximately 40 Jovian irregular satellites of this size remained undiscovered in 2012.
In September 2020, researchers from the University of British Columbia identified 45 candidate irregular moons from an analysis of archival images taken in 2010 by the CFHT. These candidates were mainly small and faint, down to magnitude of 25.7 or above in diameter. From the number of candidate moons detected within a sky area of one square degree, the team extrapolated that the population of retrograde Jovian moons brighter than magnitude 25.7 is around within a factor of 2. Although the team considers their characterized candidates to be likely moons of Jupiter, they all remain unconfirmed due to insufficient observation data for determining reliable orbits. The true population of Jovian irregular moons is likely complete down to magnitude 23.2 at diameters over .
List
The moons of Jupiter are listed below by orbital period. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold. These are the four Galilean moons, which are comparable in size to the Moon. The other moons are much smaller. The Galilean moon with the smallest amount of mass is greater than 7,000 times more massive than the most massive of the other moons. The irregular captured moons are shaded light gray and orange when prograde and yellow, red, and dark gray when retrograde.
The orbits and mean distances of the irregular moons are highly variable over short timescales due to frequent planetary and solar perturbations, so proper orbital elements which are averaged over a period of time are preferably used. The proper orbital elements of the irregular moons listed here are averaged over a 400-year numerical integration by the Jet Propulsion Laboratory: for the above reasons, they may strongly differ from osculating orbital elements provided by other sources. Otherwise, recently discovered irregular moons without published proper elements are temporarily listed here with inaccurate osculating orbital elements that are italicized to distinguish them from other irregular moons with proper orbital elements. Some of the irregular moons' proper orbital periods in this list may not scale accordingly with their proper semi-major axes due to the aforementioned perturbations. The irregular moons' proper orbital elements are all based on the reference epoch of 1 January 2000. | Moons of Jupiter | Wikipedia | 506 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Some irregular moons have only been observed briefly for a year or two, but their orbits are known accurately enough that they will not be lost to positional uncertainties.
Exploration
Nine spacecraft have visited Jupiter. The first were Pioneer 10 in 1973, and Pioneer 11 a year later, taking low-resolution images of the four Galilean moons and returning data on their atmospheres and radiation belts. The Voyager 1 and Voyager 2 probes visited Jupiter in 1979, discovering the volcanic activity on Io and the presence of water ice on the surface of Europa. Ulysses further studied Jupiter's magnetosphere in 1992 and then again in 2000.
The Galileo spacecraft was the first to enter orbit around Jupiter, arriving in 1995 and studying it until 2003. During this period, Galileo gathered a large amount of information about the Jovian system, making close approaches to all of the Galilean moons and finding evidence for thin atmospheres on three of them, as well as the possibility of liquid water beneath the surfaces of Europa, Ganymede, and Callisto. It also discovered a magnetic field around Ganymede.
Then the Cassini probe to Saturn flew by Jupiter in 2000 and collected data on interactions of the Galilean moons with Jupiter's extended atmosphere. The New Horizons spacecraft flew by Jupiter in 2007 and made improved measurements of its satellites' orbital parameters.
In 2016, the Juno spacecraft imaged the Galilean moons from above their orbital plane as it approached Jupiter orbit insertion, creating a time-lapse movie of their motion. With a mission extension, Juno has since begun close flybys of the Galileans, flying by Ganymede in 2021 followed by Europa and Io in 2022. It flew by Io again in late 2023 and once more in early 2024. | Moons of Jupiter | Wikipedia | 357 | 575613 | https://en.wikipedia.org/wiki/Moons%20of%20Jupiter | Physical sciences | Solar System | Astronomy |
Cheminformatics (also known as chemoinformatics) refers to the use of physical chemistry theory with computer and information science techniques—so called "in silico" techniques—in application to a range of descriptive and prescriptive problems in the field of chemistry, including in its applications to biology and related molecular fields. Such in silico techniques are used, for example, by pharmaceutical companies and in academic settings to aid and inform the process of drug discovery, for instance in the design of well-defined combinatorial libraries of synthetic compounds, or to assist in structure-based drug design. The methods can also be used in chemical and allied industries, and such fields as environmental science and pharmacology, where chemical processes are involved or studied.
History
Cheminformatics has been an active field in various guises since the 1970s and earlier, with activity in academic departments and commercial pharmaceutical research and development departments. The term chemoinformatics was defined in its application to drug discovery by F.K. Brown in 1998:Chemoinformatics is the mixing of those information resources to transform data into information and information into knowledge for the intended purpose of making better decisions faster in the area of drug lead identification and optimization. Since then, both terms, cheminformatics and chemoinformatics, have been used, although, lexicographically, cheminformatics appears to be more frequently used, despite academics in Europe declaring for the variant chemoinformatics in 2006. In 2009, a prominent Springer journal in the field was founded by transatlantic executive editors named the Journal of Cheminformatics.
Background
Cheminformatics combines the scientific working fields of chemistry, computer science, and information science—for example in the areas of topology, chemical graph theory, information retrieval and data mining in the chemical space. Cheminformatics can also be applied to data analysis for various industries like paper and pulp, dyes and such allied industries.
Applications
Storage and retrieval
A primary application of cheminformatics is the storage, indexing, and search of information relating to chemical compounds. The efficient search of such stored information includes topics that are dealt with in computer science, such as data mining, information retrieval, information extraction, and machine learning. Related research topics include:
Digital libraries
Unstructured data
Structured data mining and mining of structured data
Database mining
Graph mining
Molecule mining
Sequence mining
Tree mining
File formats | Cheminformatics | Wikipedia | 492 | 575697 | https://en.wikipedia.org/wiki/Cheminformatics | Physical sciences | Basics_2 | Chemistry |
The in silico representation of chemical structures uses specialized formats such as the Simplified molecular input line entry specifications (SMILES) or the XML-based Chemical Markup Language. These representations are often used for storage in large chemical databases. While some formats are suited for visual representations in two- or three-dimensions, others are more suited for studying physical interactions, modeling and docking studies.
Virtual libraries
Chemical data can pertain to real or virtual molecules. Virtual libraries of compounds may be generated in various ways to explore chemical space and hypothesize novel compounds with desired properties. Virtual libraries of classes of compounds (drugs, natural products, diversity-oriented synthetic products) were recently generated using the FOG (fragment optimized growth) algorithm. This was done by using cheminformatic tools to train transition probabilities of a Markov chain on authentic classes of compounds, and then using the Markov chain to generate novel compounds that were similar to the training database.
Virtual screening
In contrast to high-throughput screening, virtual screening involves computationally
screening in silico libraries of compounds, by means of various methods such as
docking, to identify members likely to possess desired properties
such as biological activity against a given target. In some cases, combinatorial chemistry is used in the development of the library to increase the efficiency in mining the chemical space. More commonly, a diverse library of small molecules or natural products is screened.
Quantitative structure-activity relationship (QSAR)
This is the calculation of quantitative structure–activity relationship and quantitative structure property relationship values, used to predict the activity of compounds from their structures. In this context there is also a strong relationship to chemometrics. Chemical expert systems are also relevant, since they represent parts of chemical knowledge as an in silico representation. There is a relatively new concept of matched molecular pair analysis or prediction-driven MMPA which is coupled with QSAR model in order to identify activity cliff. | Cheminformatics | Wikipedia | 391 | 575697 | https://en.wikipedia.org/wiki/Cheminformatics | Physical sciences | Basics_2 | Chemistry |
The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of meters across to the enormous Titan, which is larger than the planet Mercury. There are 146 moons with confirmed orbits, the most of any planet in the Solar System. This number does not include the many thousands of moonlets embedded within Saturn's dense rings, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Seven Saturnian moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two of those, Titan and possibly Rhea, are currently in hydrostatic equilibrium. Three moons are particularly notable. Titan is the second-largest moon in the Solar System (after Jupiter's Ganymede), with a nitrogen-rich Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes. Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow. Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains among the tallest in the solar system.
Twenty-four of the known moons are regular satellites; they have prograde orbits not greatly inclined to Saturn's equatorial plane, with the exception of Iapetus which has a prograde but highly inclined orbit, an unusual characteristic for a regular moon. They include the seven major satellites, four small moons that exist in a trojan orbit with larger moons, and five that act as shepherd moons, of which two are mutually co-orbital. Two tiny moons orbit inside of Saturn's B and G rings. The relatively large Hyperion is locked in an orbital resonance with Titan. The remaining regular moons orbit near the outer edges of the dense A Ring and the narrow F Ring, and between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn. | Moons of Saturn | Wikipedia | 394 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The remaining 122, with mean diameters ranging from , orbit much farther from Saturn. They are irregular satellites, having high orbital inclinations and eccentricities mixed between prograde and retrograde. These moons are probably captured minor planets, or fragments from the collisional breakup of such bodies after they were captured, creating collisional families. Saturn is expected to have around 150 irregular satellites larger than in diameter, plus many hundreds more that are even smaller. The irregular satellites are classified by their orbital characteristics into the prograde Inuit and Gallic groups and the large retrograde Norse group, and their names are chosen from the corresponding mythologies (with the Gallic group corresponding to Celtic mythology). The sole exception is Phoebe, the largest irregular Saturnian moon, discovered at the end of the 19th century; it is part of the Norse group but named for a Greek Titaness.
The rings of Saturn are made up of objects ranging in size from microscopic to moonlets hundreds of meters across, each in its own orbit around Saturn. Thus an absolute number of Saturnian moons cannot be given, because there is no consensus on a boundary between the countless small unnamed objects that form Saturn's ring system and the larger objects that have been named as moons. Over 150 moonlets embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects.
, there are 83 designated moons that are still unnamed; all but one (the designated B-ring moonlet S/2009 S 1) are irregular. (There are many other undesignated ring moonlets.) If named, most of the irregulars will receive names from Gallic, Norse and Inuit mythology based on the orbital group of which they are a member.
Discovery
Early observations
Before the advent of telescopic photography, eight moons of Saturn were discovered by direct observation using optical telescopes. Saturn's largest moon, Titan, was discovered in 1655 by Christiaan Huygens using a objective lens on a refracting telescope of his own design. Tethys, Dione, Rhea and Iapetus (the "Sidera Lodoicea") were discovered between 1671 and 1684 by Giovanni Domenico Cassini. Mimas and Enceladus were discovered in 1789 by William Herschel. Hyperion was discovered in 1848 by W. C. Bond, G. P. Bond and William Lassell. | Moons of Saturn | Wikipedia | 498 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The use of long-exposure photographic plates made possible the discovery of additional moons. The first to be discovered in this manner, Phoebe, was found in 1899 by W. H. Pickering. In 1966 the tenth satellite of Saturn was discovered by Audouin Dollfus, when the rings were observed edge-on near an equinox. It was later named Janus. A few years later it was realized that all observations of 1966 could only be explained if another satellite had been present and that it had an orbit similar to that of Janus. This object is now known as Epimetheus, the eleventh moon of Saturn. It shares the same orbit with Janus—the only known example of co-orbitals in the Solar System. In 1980, three additional Saturnian moons were discovered from the ground and later confirmed by the Voyager probes. They are trojan moons of Dione (Helene) and Tethys (Telesto and Calypso).
Observations by spacecraft
The study of the outer planets has since been revolutionized by the use of uncrewed space probes. The arrival of the Voyager spacecraft at Saturn in 1980–1981 resulted in the discovery of three additional moons—Atlas, Prometheus and Pandora—bringing the total to 17. In addition, Epimetheus was confirmed as distinct from Janus. In 1990, Pan was discovered in archival Voyager images.
The Cassini mission, which arrived at Saturn in July 2004, initially discovered three small inner moons: Methone and Pallene between Mimas and Enceladus, and the second trojan moon of Dione, Polydeuces. It also observed three suspected but unconfirmed moons in the F Ring. In Cassini scientists announced that the structure of Saturn's rings indicates the presence of several more moons orbiting within the rings, although only one, Daphnis, had been visually confirmed at the time. In 2007 Anthe was announced. In 2008 it was reported that Cassini observations of a depletion of energetic electrons in Saturn's magnetosphere near Rhea might be the signature of a tenuous ring system around Saturn's second largest moon. In , Aegaeon, a moonlet within the G Ring, was announced. In July of the same year, S/2009 S 1, the first moonlet within the B Ring, was observed. In April 2014, the possible beginning of a new moon, within the A Ring, was reported. (related image)
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Study of Saturn's moons has also been aided by advances in telescope instrumentation, primarily the introduction of digital charge-coupled devices which replaced photographic plates. For the 20th century, Phoebe stood alone among Saturn's known moons with its highly irregular orbit. Then in 2000, three dozen additional irregular moons were discovered using ground-based telescopes. A survey starting in late 2000 and conducted using three medium-size telescopes found thirteen new moons orbiting Saturn at a great distance, in eccentric orbits, which are highly inclined to both the equator of Saturn and the ecliptic. They are probably fragments of larger bodies captured by Saturn's gravitational pull. In 2005, astronomers using the Mauna Kea Observatory announced the discovery of twelve more small outer moons, in 2006, astronomers using the Subaru 8.2 m telescope reported the discovery of nine more irregular moons, in , Tarqeq (S/2007 S 1) was announced and in May of the same year S/2007 S 2 and S/2007 S 3 were reported. In 2019, twenty new irregular satellites of Saturn were reported, resulting in Saturn overtaking Jupiter as the planet with the most known moons for the first time since 2000.
In 2019, researchers Edward Ashton, Brett Gladman, and Matthew Beaudoin conducted a survey of Saturn's Hill sphere using the 3.6-meter Canada–France–Hawaii Telescope and discovered about 80 new Saturnian irregular moons. Follow-up observations of these new moons took place over 2019–2021, eventually leading to S/2019 S 1 being announced in November 2021 and an additional 62 moons being announced from 3–16 May 2023. These discoveries brought Saturn's total number of confirmed moons up to 145, making it the first planet known to have over 100 moons. Yet another moon, S/2006 S 20, was announced on 23 May 2023, bringing Saturn's total count moons to 146. All of these new moons are small and faint, with diameters over and apparent magnitudes of 25–27. The researchers found that the Saturnian irregular moon population is more abundant at smaller sizes, suggesting that they are likely fragments from a collision that occurred a few hundred million years ago. The researchers extrapolated that the true population of Saturnian irregular moons larger than in diameter amounts to , which is approximately three times as many Jovian irregular moons down to the same size. If this size distribution applies to even smaller diameters, Saturn would therefore intrinsically have more irregular moons than Jupiter.
Naming | Moons of Saturn | Wikipedia | 505 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The modern names for Saturnian moons were suggested by John Herschel in 1847. He proposed to name them after mythological figures associated with the Roman god of agriculture and harvest, Saturn (equated to the Greek Cronus). In particular, the then known seven satellites were named after Titans, Titanesses and Giants – brothers and sisters of Cronus. The idea was similar to Simon Marius' mythological naming scheme for the moons of Jupiter.
As Saturn devoured his children, his family could not be assembled around him, so that the choice lay among his brothers and sister, the Titans and Titanesses. The name Iapetus seemed indicated by the obscurity and remoteness of the exterior satellite, Titan by the superior size of the Huyghenian, while the three female appellations [Rhea, Dione, and Tethys] class together the three intermediate Cassinian satellites. The minute interior ones seemed appropriately characterized by a return to male appellations [Enceladus and Mimas] chosen from a younger and inferior (though still superhuman) brood. [Results of the Astronomical Observations made ... at the Cape of Good Hope, p. 415]
In 1848, Lassell proposed that the eighth satellite of Saturn be named Hyperion after another Titan. When in the 20th century the names of Titans were exhausted, the moons were named after different characters of the Greco-Roman mythology or giants from other mythologies. All the irregular moons (except Phoebe, discovered about a century before the others) are named after Inuit, and Gallic gods, and after Norse ice giants.
Some asteroids share the same names as moons of Saturn: 55 Pandora, 106 Dione, 577 Rhea, 1809 Prometheus, 1810 Epimetheus, and 4450 Pan. In addition, three more asteroids would share the names of Saturnian moons but for spelling differences made permanent by the International Astronomical Union (IAU): Calypso and asteroid 53 Kalypso; Helene and asteroid 101 Helena; and Gunnlod and asteroid 657 Gunlöd.
Physical characteristics
Saturn's satellite system is very lopsided: one moon, Titan, comprises more than 96% of the mass in orbit around the planet. The six other planemo (ellipsoidal) moons constitute roughly 4% of the mass, and the remaining small moons, together with the rings, comprise only 0.04%. | Moons of Saturn | Wikipedia | 490 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Orbital groups
Although the boundaries may be somewhat vague, Saturn's moons can be divided into ten groups according to their orbital characteristics. Many of them, such as Pan and Daphnis, orbit within Saturn's ring system and have orbital periods only slightly longer than the planet's rotation period. The innermost moons and most regular satellites all have mean orbital inclinations ranging from less than a degree to about 1.5 degrees (except Iapetus, which has an inclination of 7.57 degrees) and small orbital eccentricities. On the other hand, irregular satellites in the outermost regions of Saturn's moon system, in particular the Norse group, have orbital radii of millions of kilometers and orbital periods lasting several years. The moons of the Norse group also orbit in the opposite direction to Saturn's rotation.
Inner moons
Ring moonlets
During late July 2009, a moonlet, S/2009 S 1, was discovered in the B Ring, 480 km from the outer edge of the ring, by the shadow it cast. It is estimated to be 300 m in diameter. Unlike the A Ring moonlets (see below), it does not induce a 'propeller' feature, probably due to the density of the B Ring.
In 2006, four tiny moonlets were found in Cassini images of the A Ring. Before this discovery only two larger moons had been known within gaps in the A Ring: Pan and Daphnis. These are large enough to clear continuous gaps in the ring. In contrast, a moonlet is only massive enough to clear two small—about 10 km across—partial gaps in the immediate vicinity of the moonlet itself creating a structure shaped like an airplane propeller. The moonlets themselves are tiny, ranging from about 40 to 500 meters in diameter, and are too small to be seen directly. | Moons of Saturn | Wikipedia | 370 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
In 2007, the discovery of 150 more moonlets revealed that they (with the exception of two that have been seen outside the Encke gap) are confined to three narrow bands in the A Ring between 126,750 and 132,000 km from Saturn's center. Each band is about a thousand kilometers wide, which is less than 1% the width of Saturn's rings. This region is relatively free from the disturbances caused by resonances with larger satellites, although other areas of the A Ring without disturbances are apparently free of moonlets. The moonlets were probably formed from the breakup of a larger satellite. It is estimated that the A Ring contains 7,000–8,000 propellers larger than 0.8 km in size and millions larger than 0.25 km. In April 2014, NASA scientists reported the possible consolidation of a new moon within the A Ring, implying that Saturn's present moons may have formed in a similar process in the past when Saturn's ring system was much more massive.
Similar moonlets may reside in the F Ring. There, "jets" of material may be due to collisions, initiated by perturbations from the nearby small moon Prometheus, of these moonlets with the core of the F Ring. One of the largest F Ring moonlets may be the as-yet unconfirmed object S/2004 S 6. The F Ring also contains transient "fans" which are thought to result from even smaller moonlets, about 1 km in diameter, orbiting near the F Ring core.
One recently discovered moon, Aegaeon, resides within the bright arc of G Ring and is trapped in the 7:6 mean-motion resonance with Mimas. This means that it makes exactly seven revolutions around Saturn while Mimas makes exactly six. The moon is the largest among the population of bodies that are sources of dust in this ring.
Ring shepherds | Moons of Saturn | Wikipedia | 382 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Shepherd satellites are small moons that orbit within, or just beyond, a planet's ring system. They have the effect of sculpting the rings: giving them sharp edges, and creating gaps between them. Saturn's shepherd moons are Pan (Encke gap), Daphnis (Keeler gap), Prometheus (F Ring), Janus (A Ring), and Epimetheus (A Ring). These moons probably formed as a result of accretion of the friable ring material on preexisting denser cores. The cores with sizes from one-third to one-half the present-day moons may be themselves collisional shards formed when a parental satellite of the rings disintegrated.
Janus and Epimetheus are co-orbital moons. They are of similar size, with Janus being somewhat larger than Epimetheus. They have orbits with less than a 100-kilometer difference in semi-major axis, close enough that they would collide if they attempted to pass each other. Instead of colliding, their gravitational interaction causes them to swap orbits every four years.
Other inner moons
Other inner moons that are neither ring shepherds nor ring moonlets include Atlas and Pandora.
Inner large | Moons of Saturn | Wikipedia | 257 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The innermost large moons of Saturn orbit within its tenuous E Ring, along with three smaller moons of the Alkyonides group.
Mimas is the smallest and least massive of the inner round moons, although its mass is sufficient to alter the orbit of Methone. It is noticeably ovoid-shaped, having been made shorter at the poles and longer at the equator (by about 20 km) by the effects of Saturn's gravity. Mimas has a large impact crater one-third its diameter, Herschel, situated on its leading hemisphere Mimas has no known past or present geologic activity and its surface is dominated by impact craters, though it does have a water ocean 20–30 km beneath the surface. The only tectonic features known are a few arcuate and linear troughs, which probably formed when Mimas was shattered by the Herschel impact.
Enceladus is one of the smallest of Saturn's moons that is spherical in shape—only Mimas is smaller—yet is the only small Saturnian moon that is currently endogenously active, and the smallest known body in the Solar System that is geologically active today. Its surface is morphologically diverse; it includes ancient heavily cratered terrain as well as younger smooth areas with few impact craters. Many plains on Enceladus are fractured and intersected by systems of lineaments. The area around its south pole was found by Cassini to be unusually warm and cut by a system of fractures about 130 km long called "tiger stripes", some of which emit jets of water vapor and dust. These jets form a large plume off its south pole, which replenishes Saturn's E ring and serves as the main source of ions in the magnetosphere of Saturn. The gas and dust are released with a rate of more than 100 kg/s. Enceladus may have liquid water underneath the south-polar surface. The source of the energy for this cryovolcanism is thought to be a 2:1 mean-motion resonance with Dione. The pure ice on the surface makes Enceladus one of the brightest known objects in the Solar System—its geometrical albedo is more than 140%. | Moons of Saturn | Wikipedia | 452 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Tethys is the third largest of Saturn's inner moons. Its most prominent features are a large (400 km diameter) impact crater named Odysseus on its leading hemisphere and a vast canyon system named Ithaca Chasma extending at least 270° around Tethys. The Ithaca Chasma is concentric with Odysseus, and these two features may be related. Tethys appears to have no current geological activity. A heavily cratered hilly terrain occupies the majority of its surface, while a smaller and smoother plains region lies on the hemisphere opposite to that of Odysseus. The plains contain fewer craters and are apparently younger. A sharp boundary separates them from the cratered terrain. There is also a system of extensional troughs radiating away from Odysseus. The density of Tethys (0.985 g/cm3) is less than that of water, indicating that it is made mainly of water ice with only a small fraction of rock.
Dione is the second-largest inner moon of Saturn. It has a higher density than the geologically dead Rhea, the largest inner moon, but lower than that of active Enceladus. While the majority of Dione's surface is heavily cratered old terrain, this moon is also covered with an extensive network of troughs and lineaments, indicating that in the past it had global tectonic activity. The troughs and lineaments are especially prominent on the trailing hemisphere, where several intersecting sets of fractures form what is called "wispy terrain". The cratered plains have a few large impact craters reaching 250 km in diameter. Smooth plains with low impact-crater counts are also present on a small fraction of its surface. They were probably tectonically resurfaced relatively later in the geological history of Dione. At two locations within smooth plains strange landforms (depressions) resembling oblong impact craters have been identified, both of which lie at the centers of radiating networks of cracks and troughs; these features may be cryovolcanic in origin. Dione may be geologically active even now, although on a scale much smaller than the cryovolcanism of Enceladus. This follows from Cassini magnetic measurements that show Dione is a net source of plasma in the magnetosphere of Saturn, much like Enceladus. | Moons of Saturn | Wikipedia | 484 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Alkyonides
Three small moons orbit between Mimas and Enceladus: Methone, Anthe, and Pallene. Named after the Alkyonides of Greek mythology, they are some of the smallest moons in the Saturn system. Anthe and Methone have very faint ring arcs along their orbits, whereas Pallene has a faint complete ring. Of these three moons, only Methone has been photographed at close range, showing it to be egg-shaped with very few or no craters.
Trojan
Trojan moons are a unique feature only known from the Saturnian system. A trojan body orbits at either the leading L4 or trailing L5 Lagrange point of a much larger object, such as a large moon or planet. Tethys has two trojan moons, Telesto (leading) and Calypso (trailing), and Dione also has two, Helene (leading) and Polydeuces (trailing). Helene is by far the largest trojan moon, while Polydeuces is the smallest and has the most chaotic orbit. These moons are coated with dusty material that has smoothed out their surfaces.
Outer large | Moons of Saturn | Wikipedia | 231 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
These moons all orbit beyond the E Ring. They are:
Rhea is the second-largest of Saturn's moons. It is even slightly larger than Oberon, the second-largest moon of Uranus. In 2005, Cassini detected a depletion of electrons in the plasma wake of Rhea, which forms when the co-rotating plasma of Saturn's magnetosphere is absorbed by the moon. The depletion was hypothesized to be caused by the presence of dust-sized particles concentrated in a few faint equatorial rings. Such a ring system would make Rhea the only moon in the Solar System known to have rings. Subsequent targeted observations of the putative ring plane from several angles by Cassini'''s narrow-angle camera turned up no evidence of the expected ring material, leaving the origin of the plasma observations unresolved. Otherwise Rhea has rather a typical heavily cratered surface, with the exceptions of a few large Dione-type fractures (wispy terrain) on the trailing hemisphere and a very faint "line" of material at the equator that may have been deposited by material deorbiting from present or former rings. Rhea also has two very large impact basins on its anti-Saturnian hemisphere, which are about 400 and 500 km across. The first, Tirawa, is roughly comparable to the Odysseus basin on Tethys. There is also a 48 km-diameter impact crater called Inktomi at 112°W that is prominent because of an extended system of bright rays, which may be one of the youngest craters on the inner moons of Saturn. No evidence of any endogenic activity has been discovered on the surface of Rhea. | Moons of Saturn | Wikipedia | 343 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Titan, at 5,149 km diameter, is the second largest moon in the Solar System and Saturn's largest. Out of all the large moons, Titan is the only one with a dense (surface pressure of 1.5 atm), cold atmosphere, primarily made of nitrogen with a small fraction of methane. The dense atmosphere frequently produces bright white convective clouds, especially over the south pole region. On 6 June 2013, scientists at the IAA-CSIC reported the detection of polycyclic aromatic hydrocarbons in the upper atmosphere of Titan. On 23 June 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times. The surface of Titan, which is difficult to observe due to persistent atmospheric haze, shows only a few impact craters and is probably very young. It contains a pattern of light and dark regions, flow channels and possibly cryovolcanos. Some dark regions are covered by longitudinal dune fields shaped by tidal winds, where sand is made of frozen water or hydrocarbons. Titan is the only body in the Solar System beside Earth with bodies of liquid on its surface, in the form of methane–ethane lakes in Titan's north and south polar regions. The largest lake, Kraken Mare, is larger than the Caspian Sea. Like Europa and Ganymede, it is believed that Titan has a subsurface ocean made of water mixed with ammonia, which can erupt to the surface of the moon and lead to cryovolcanism. On 2 July 2014, NASA reported the ocean inside Titan may be "as salty as the Earth's Dead Sea". | Moons of Saturn | Wikipedia | 354 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Hyperion is Titan's nearest neighbor in the Saturn system. The two moons are locked in a 4:3 mean-motion resonance with each other, meaning that while Titan makes four revolutions around Saturn, Hyperion makes exactly three. With an average diameter of about 270 km, Hyperion is smaller and lighter than Mimas. It has an extremely irregular shape, and a very odd, tan-colored icy surface resembling a sponge, though its interior may be partially porous as well. The average density of about 0.55 g/cm3 indicates that the porosity exceeds 40% even assuming it has a purely icy composition. The surface of Hyperion is covered with numerous impact craters—those with diameters 2–10 km are especially abundant. It is the only moon besides the small moons of Pluto known to have a chaotic rotation, which means Hyperion has no well-defined poles or equator. While on short timescales the satellite approximately rotates around its long axis at a rate of 72–75° per day, on longer timescales its axis of rotation (spin vector) wanders chaotically across the sky. This makes the rotational behavior of Hyperion essentially unpredictable. | Moons of Saturn | Wikipedia | 240 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Iapetus is the third-largest of Saturn's moons. Orbiting the planet at km, it is by far the most distant of Saturn's large moons, and also has the largest orbital inclination, at 15.47°. Iapetus has long been known for its unusual two-toned surface; its leading hemisphere is pitch-black and its trailing hemisphere is almost as bright as fresh snow. Cassini images showed that the dark material is confined to a large near-equatorial area on the leading hemisphere called Cassini Regio, which extends approximately from 40°N to 40°S. The pole regions of Iapetus are as bright as its trailing hemisphere. Cassini also discovered a 20 km tall equatorial ridge, which spans nearly the moon's entire equator. Otherwise both dark and bright surfaces of Iapetus are old and heavily cratered. The images revealed at least four large impact basins with diameters from 380 to 550 km and numerous smaller impact craters. No evidence of any endogenic activity has been discovered. A clue to the origin of the dark material covering part of Iapetus's starkly dichromatic surface may have been found in 2009, when NASA's Spitzer Space Telescope discovered a vast, nearly invisible disk around Saturn, just inside the orbit of the moon Phoebe – the Phoebe ring. Scientists believe that the disk originates from dust and ice particles kicked up by impacts on Phoebe. Because the disk particles, like Phoebe itself, orbit in the opposite direction to Iapetus, Iapetus collides with them as they drift in the direction of Saturn, darkening its leading hemisphere slightly. Once a difference in albedo, and hence in average temperature, was established between different regions of Iapetus, a thermal runaway process of water ice sublimation from warmer regions and deposition of water vapor onto colder regions ensued. Iapetus's present two-toned appearance results from the contrast between the bright, primarily ice-coated areas and regions of dark lag, the residue left behind after the loss of surface ice. | Moons of Saturn | Wikipedia | 416 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Irregular
Irregular moons are small satellites with large-radii, inclined, and frequently retrograde orbits, believed to have been acquired by the parent planet through a capture process. They often occur as collisional families or groups. The precise size as well as albedo of the irregular moons are not known for sure because the moons are very small to be resolved by a telescope, although the latter is usually assumed to be quite low—around 6% (albedo of Phoebe) or less. The irregulars generally have featureless visible and near infrared spectra dominated by water absorption bands. They are neutral or moderately red in color—similar to C-type, P-type, or D-type asteroids, though they are much less red than Kuiper belt objects.
Inuit
The Inuit group includes thirteen prograde outer moons that are similar enough in their distances from the planet (190–300 radii of Saturn), their orbital inclinations (45–50°) and their colors that they can be considered a group. The Inuit group is further split into three distinct subgroups at different semi-major axes, and are named after their respective largest members. Ordered by increasing semi-major axis, these subgroups are the Kiviuq group, the Paaliaq group, and the Siarnaq group. The Kiviuq group includes five members: Kiviuq, Ijiraq, S/2005 S 4, S/2019 S 1, and S/2020 S 1. The Siarnaq group includes seven members: Siarnaq, Tarqeq, S/2004 S 31, S/2019 S 14, S/2020 S 3, S/2019 S 6, and S/2020 S 5. In contrast to the Kiviuq and Siarnaq subgroups, the Paaliaq subgroup does not contain any other known members besides Paaliaq itself. Of the entire Inuit group, Siarnaq is the largest member with an estimated size of about 39 km.
Gallic | Moons of Saturn | Wikipedia | 415 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The Gallic group includes seven prograde outer moons that are similar enough in their distance from the planet (200–300 radii of Saturn), their orbital inclination (35–40°) and their color that they can be considered a group. They are Albiorix, Bebhionn, Erriapus, Tarvos, Saturn LX, S/2007 S 8, and S/2020 S 4. The largest of these moons is Albiorix with an estimated diameter of about 29 km.
Norse
All 100 retrograde outer moons of Saturn are broadly classified into the Norse group. They are Aegir, Angrboda, Alvaldi, Beli, Bergelmir, Bestla, Eggther, Farbauti, Fenrir, Fornjot, Geirrod, Gerd, Greip, Gridr, Gunnlod, Hati, Hyrrokkin, Jarnsaxa, Kari, Loge, Mundilfari, Narvi, Phoebe, Skathi, Skoll, Skrymir, Surtur, Suttungr, Thiazzi, Thrymr, Ymir, and 69 unnamed satellites. After Phoebe, Ymir is the largest of the known retrograde irregular moons, with an estimated diameter of only 22 km.
Phoebe, at in diameter, is by far the largest of Saturn's irregular satellites. It has a retrograde orbit and rotates on its axis every 9.3 hours. Phoebe was the first moon of Saturn to be studied in detail by Cassini, in ; during this encounter Cassini was able to map nearly 90% of the moon's surface. Phoebe has a nearly spherical shape and a relatively high density of about 1.6 g/cm3. Cassini images revealed a dark surface scarred by numerous impacts—there are about 130 craters with diameters exceeding 10 km. Such impacts may have ejected fragments of Phoebe into orbit around Saturn—two of these may be S/2006 S 20 and S/2006 S 9, whose orbits are similar to Phoebe. Spectroscopic measurement showed that the surface is made of water ice, carbon dioxide, phyllosilicates, organics and possibly iron-bearing minerals. Phoebe is believed to be a captured centaur that originated in the Kuiper belt. It also serves as a source of material for the largest known ring of Saturn, which darkens the leading hemisphere of Iapetus (see above). | Moons of Saturn | Wikipedia | 505 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Outlier prograde satellites
Two prograde moons of Saturn do not definitively belong to either the Inuit or Gallic groups. S/2004 S 24 and S/2006 S 12 have similar orbital inclinations as the Gallic group, but have much more distant orbits with semi-major axes of ~400 Saturn radii and ~340 Saturn radii, respectively.
List
Confirmed
The Saturnian moons are listed here by orbital period (or semi-major axis), from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold and marked with a blue background, while the irregular moons are listed in red, orange, green, and gray background. The orbits and mean distances of the irregular moons are strongly variable over short timescales due to frequent planetary and solar perturbations, so the orbital elements of irregular moons listed here are averaged over a 5,000-year numerical integration by the Jet Propulsion Laboratory. These may sometimes strongly differ from the osculating orbital elements provided by other sources. Their orbital elements are all based on a reference epoch of 1 January 2000.
Unconfirmed
These F Ring moonlets listed in the following table (observed by Cassini) have not been confirmed as solid bodies. It is not yet clear if these are real satellites or merely persistent clumps within the F Ring.
Spurious
Two moons were claimed to be discovered by different astronomers but never seen again. Both moons were said to orbit between Titan and Hyperion.
Chiron which was supposedly sighted by Hermann Goldschmidt in 1861, but never observed by anyone else.
Themis was allegedly discovered in 1905 by astronomer William Pickering, but never seen again. Nevertheless, it was included in numerous almanacs and astronomy books until the 1960s.
Hypothetical
In 2022, scientists of the Massachusetts Institute of Technology proposed the hypothetical former moon Chrysalis, using data from the Cassini–Huygens mission. Chrysalis would have orbited between Titan and Iapetus, but its orbit would have gradually become more eccentric until it was torn apart by Saturn. 99% of its mass would have been absorbed by Saturn, while the remaining 1% would have formed Saturn's rings. | Moons of Saturn | Wikipedia | 450 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
Temporary
Much like Jupiter, asteroids and comets will infrequently make close approaches to Saturn, even more infrequently becoming captured into orbit of the planet. The comet P/2020 F1 (Leonard) is calculated to have made a close approach of km ( mi) to Saturn on 8 May 1936, closer than the orbit of Titan to the planet, with an orbital eccentricity of only . The comet may have been orbiting Saturn prior to this as a temporary satellite, but difficulty modelling the non-gravitational forces makes whether or not it was indeed a temporary satellite uncertain.
Other comets and asteroids may have temporarily orbited Saturn at some point, but none are presently known to have.
Formation
It is thought that the Saturnian system of Titan, mid-sized moons, and rings developed from a set-up closer to the Galilean moons of Jupiter, though the details are unclear. It has been proposed either that a second Titan-sized moon broke up, producing the rings and inner mid-sized moons, or that two large moons fused to form Titan, with the collision scattering icy debris that formed the mid-sized moons. On 23 June 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times. Studies based on Enceladus's tidal-based geologic activity and the lack of evidence of extensive past resonances in Tethys, Dione, and Rhea's orbits suggest that the moons up to and including Rhea may be only 100 million years old. | Moons of Saturn | Wikipedia | 326 | 575749 | https://en.wikipedia.org/wiki/Moons%20of%20Saturn | Physical sciences | Solar System | Astronomy |
The house mouse (Mus musculus) is a small mammal of the order Rodentia, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. It is one of the most abundant species of the genus Mus. Although a wild animal, the house mouse has benefited significantly from associating with human habitation to the point that truly wild populations are significantly less common than the semi-tame populations near human activity.
The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse, which is one of the most important model organisms in biology and medicine. The complete mouse reference genome was sequenced in 2002.
Characteristics
House mice have an adult body length (nose to base of tail) of and a tail length of . The weight is typically . In the wild they vary in color from grey and light brown to black (individual hairs are actually agouti coloured), but domesticated fancy mice and laboratory mice are produced in many colors ranging from white to champagne to black. They have short hair and some, but not all, sub-species have a light belly. The ears and tail have little hair. The hind feet are short compared to Apodemus mice, only long; the normal gait is a run with a stride of about , though they can jump vertically up to . The voice is a high-pitched squeak. House mice thrive under a variety of conditions; they are found in and around homes and commercial structures, as well as in open fields and agricultural lands.
Newborn males and females can be distinguished on close examination as the anogenital distance in males is about double that of the female. From the age of about 10 days, females have five pairs of mammary glands and nipples; males have no nipples. When sexually mature, the most striking and obvious difference is the presence of testicles on the males. These are large compared to the rest of the body and can be retracted into the body. | House mouse | Wikipedia | 403 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
The tail, which is used for balance, has only a thin covering of hair as it is the main peripheral organ of heat loss in thermoregulation along with—to a lesser extent—the hairless parts of the paws and ears. Blood flow to the tail can be precisely controlled in response to changes in ambient temperature using a system of arteriovenous anastomoses to increase the temperature of the skin on the tail by as much as to lose body heat. Tail length varies according to the environmental temperature of the mouse during postnatal development, so mice living in colder regions tend to have shorter tails. The tail is also used for balance when the mouse is climbing or running, or as a base when the animal stands on its hind legs (a behaviour known as tripoding), and to convey information about the dominance status of an individual in encounters with other mice.
In addition to the regular pea-sized thymus organ in the chest, house mice have a second functional pinhead-sized thymus organ in the neck next to the trachea.
Taxonomy and subspecies
Mice are mammals of the Glires clade, which means they are amongst the closest relatives of humans other than lagomorphs, treeshrews, flying lemurs and other primates.
The three widely accepted subspecies are increasingly treated as distinct species by some:
Southeastern Asian house mouse (Mus musculus castaneus) (southern and southeastern Asia)
Western European house mouse (Mus musculus domesticus); includes the fancy mouse and the laboratory mouse (Western Europe, North America, South America, Africa and Oceania)
Eastern European house mouse (Mus musculus musculus) (Eastern Europe and northern Asia)
Two additional subspecies have been recognized more recently:
Southwestern Asian house mouse (Mus musculus bactrianus) (southwestern and Central Asia). However, due to significant genetic similarity observed between (Mus musculus bactrianus) and Mus musculus castaneus, the subspecies designation for Mus musculus bactrianus has now been questioned.
pygmy house mouse (Mus musculus gentilulus) (the Arabian Peninsula and Madagascar) | House mouse | Wikipedia | 456 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
Many more subspecies' names have been given to house mice, but these are now regarded as synonyms of the five subspecies. Some populations are hybrids of different subspecies, including the Japanese house mouse (M. m. molossinus). A notable region of hybridization is a region in general Europe where M. m. domesticus and M. m. musculus are often found to hybridize. However, male hybrid mice typically experience hybrid sterility, which maintains reproductive separation between the two subspecies.
Chromosomal races
The standard species karyotype is composed of 40 chromosomes. Within Western Europe there are numerous populations – chromosomal races – with a reduced chromosome count arising from Robertsonian fusion.
Evolution
Suzuki et al., 2013 confirms the theory that M. musculus originates in Southwestern Asia and identifies 5 subspecies and their origins: musculus in northern Eurasia, castaneus in India and Southeast Asia, a previously unknown subspecies from Nepal, domesticus in western Europe, and gentilulus in Yemen.
A recent study using 89 whole-genome sequences revealed that the modern day Mus musculus castaneus emerged from an ancestral Mus musculus population in Indian subcontinent some time around 700 kya. From there, this ancestral population migrated to Iran around 360 kya to form Mus musculus domesticus and then to Afghanistan around 260 kya to form Mus musculus musculus.
Behavior
House mice usually run, walk, or stand on all fours, but when eating, fighting, or orienting themselves, they rear up on their hind legs with additional support from the tail – a behavior known as "tripoding". Mice are good jumpers, climbers, and swimmers, and are generally considered to be thigmotactic, i.e. usually attempt to maintain contact with vertical surfaces.
Mice are mostly crepuscular or nocturnal; they are averse to bright lights. The average sleep time of a captive house mouse is reported to be 12.5 hours per day. They live in a wide variety of hidden places near food sources, and construct nests from various soft materials. Mice are territorial, and one dominant male usually lives together with several females and young mice. Dominant males respect each other's territories and normally enter another's territory only if it is vacant. If two or more males are housed together in a cage, they often become aggressive unless they have been raised together from birth. | House mouse | Wikipedia | 501 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
House mice primarily feed on plant matter, but are omnivorous. They eat their own faeces to acquire nutrients produced by bacteria in their intestines. House mice, like most other rodents, do not vomit.
Mice are generally afraid of rats which often kill and eat them, a behavior known as muricide. Despite this, free-living populations of rats and mice do exist together in forest areas in New Zealand, North America, and elsewhere. House mice are generally poor competitors and in most areas cannot survive away from human settlements in areas where other small mammals, such as wood mice, are present. However, in some areas (such as Australia), mice are able to coexist with other small rodent species.
Social behavior
The social behavior of the house mouse is not rigidly fixed into species-specific patterns but is instead adaptable to the environmental conditions, such as the availability of food and space. This adaptability allows house mice to inhabit diverse areas ranging from sandy dunes to apartment buildings.
House mice have two forms of social behaviour, the expression of which depends on the environmental context. House mice in buildings and other urbanized areas with close proximity to humans are known as commensal. Commensal mice populations often have an excessive food source resulting in high population densities and small home ranges. This causes a switch from territorial behaviour to a hierarchy of individuals. When populations have an excess of food, there is less female-female aggression, which usually occurs to gain access to food or to prevent infanticide. Male-male aggression occurs in commensal populations, mainly to defend female mates and protect a small territory. The high level of male-male aggression, with a low female-female aggression level is common in polygamous populations. The social unit of commensal house mouse populations generally consists of one male and two or more females, usually related. These groups breed cooperatively, with the females communally nursing. This cooperative breeding and rearing by related females helps increase reproductive success. When no related females are present, breeding groups can form from non-related females. | House mouse | Wikipedia | 423 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
In open areas such as shrubs and fields, the house mouse population is known as noncommensal. These populations are often limited by water or food supply and have large territories. Female-female aggression in the noncommensal house mouse populations is much higher, reaching a level generally attributed to free-ranging species. Male aggression is also higher in noncommensal populations. In commensal populations, males come into contact with other males quite frequently due to high population densities and aggression must be mediated or the risk of injury becomes too great.
Both commensal and noncommensal house mouse males aggressively defend their territory and act to exclude all intruders. Males mark their territory by scent marking with urine. In marked territories, intruders showed significantly lower aggression than the territory residents. House mice show a male-biased dispersal; males generally leave their birth sites and migrate to form new territories whereas females generally stay and are opportunistic breeders rather than seasonal.
Senses and communication
Vision
The visual apparatus of mice is basically similar to that of humans but differs in that they are dichromats and have only two types of cone cells whereas humans are trichromats and have three. This means that mice do not perceive some of the colors in the human visual spectrum. However, the ventral area of the mouse retina has a much greater density of ultraviolet-sensitive cones than other areas of the retina, although the biological significance of this structure is unknown. In 2007, mice genetically engineered to produce the third type of cone were shown to be able to distinguish a range of colors similar to that perceived by tetrachromats.
Olfaction
House mice also rely on pheromones for social communication, some of which are produced by the preputial glands of both sexes. The tear fluid and urine of male mice also contains pheromones, such as major urinary proteins. Mice detect pheromones mainly with the vomeronasal organ (Jacobson's organ), located at the bottom of the nose. | House mouse | Wikipedia | 415 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
The urine of house mice, especially that of males, has a characteristic strong odor. At least 10 different compounds, such as alkanes, alcohols, etc., are detectable in the urine. Among them, five compounds are specific to males, namely 3-cyclohexene-1-methanol, aminotriazole (3-amino-s-triazole), 4-ethyl phenol, 3-ethyl-2,7-dimethyl octane and 1-iodoundecane.
Odours from adult males or from pregnant or lactating females can speed up or retard sexual maturation in juvenile females and synchronise reproductive cycles in mature females (i.e. the Whitten effect). Odours of unfamiliar male mice may terminate pregnancies, i.e. the Bruce effect.
Tactile
Mice can sense surfaces and air movements with their whiskers which are also used during thigmotaxis. If mice are blind from birth, super-normal growth of the vibrissae occurs presumably as a compensatory response. Conversely, if the vibrissae are absent, the use of vision is intensified.
Life cycle and reproduction
Female house mice have an estrous cycle about four to six days long, with estrus itself lasting less than a day. If several females are held together under crowded conditions, they will often not have an estrus at all. If they are then exposed to male urine, they will come into estrus after 72 hours.
Male house mice court females by emitting characteristic ultrasonic calls in the 30 kHz–110 kHz range. The calls are most frequent during courtship when the male is sniffing and following the female; however, the calls continue after mating has begun, at which time the calls are coincident with mounting behaviour. Males can be induced to emit these calls by female pheromones. The vocalizations appear to differ between individuals and have been compared to bird songs because of their complexity. While females have the capability to produce ultrasonic calls, they typically do not do so during mating behaviour. | House mouse | Wikipedia | 441 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
Following copulation, female mice will normally develop a mating plug which prevents further copulation. The plug is not necessary for pregnancy initiation, as this will also occur without the plug. The presence or absence of the plug will not affect litter size either. This plug stays in place for some 24 hours. The gestation period is about 19–21 days, and they give birth to a litter of 3–14 young (average six to eight). One female can have 5 to 10 litters per year, so the mouse population can increase very quickly. Breeding occurs throughout the year. (However, animals living in the wild do not reproduce in the colder months, even though they do not hibernate.)
The pups are born blind and without fur or ears. The ears are fully developed by the fourth day, fur begins to appear at about six days and the eyes open around 13 days after birth; the pups are weaned at around 21 days. Females reach sexual maturity at about six weeks of age and males at about eight weeks, but both can copulate as early as five weeks.
Polygamy
Although house mice can be either monogamous or polygamous, they are most commonly polygamous. They generally show characteristics of mate-defense polygyny in that males are highly territorial and protective of their mates, while females are less agonistic. The communal nursing groups that result from these behaviors lead to lower numbers of infanticide since more females are able to protect greater numbers of offspring.
Evolutionary and behavioural consequences
Both evolutionary and behavioral consequences result from the polygamous nature of the house mouse. One consequence is the paternal investment, which is lower in polygamous mice than in mice that are monogamous. This occurs due to the fact that males spend more time involved in sexual competition than do females, leaving less time for paternal care. Polygamous male house mice spend less time alone with pups. They are also less likely and slower to retrieve lost pups than males of monogamous mice. In contrast, the maternal investment is similar between female mice that have mated once versus multiply. | House mouse | Wikipedia | 432 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
The polygamous behavior of female house mice promotes sperm competition, which affects both male and female evolutionary fitness. Females who mate with multiple males tend to produce both pups in greater numbers, and with higher survival rates, increasing female fitness. Sperm competition that arises from polygamy favors males with faster, more motile sperm in higher numbers, increasing male fitness. The competitive aspect of insemination increases the frequency of polyandrous events and fertilizations. Polyandry has evolved to increase reproductive success. Male mating behavior is also affected in response to the practice of polygamous behavior. Compared to monogamous house mice, polygamous house mice mate for longer periods of time. This behaviour allows for an increase in both the transfer of sperm and paternity success, which in turn increases male fitness.
Polyandry
As opposed to polygyny, polyandrous behavior in females is the act of breeding with several males in the same season. Variation in number of males that females mate with occurs among a population. Polyandrous behavior is a common mating pattern in the subspecies Mus musculus musculus as well as its relative Mus musculus domesticus.
Polyandry occurs in 30% of all wild populations of house mice. Litters from multiple sires tend to be more genetically diverse than litters of single sires. Multiple paternity is also more common in larger populations than smaller populations, because there is a larger number of mates and more diverse mates to choose from. Within a population, males and females show different levels of multiple mating. Females show bias toward unrelated males rather than related males during sexual selection, resulting in more genetically diverse offspring and a reduction of inbreeding depression. Inbreeding depression increases genetic incompatibilities, levels of homozygosity, and the chance of expression of deleterious recessive alleles. Polyandry has been shown to increase offspring survival compared to monandry.
Evolutionary consequences
The fitness of females increases in polyandrous lines due to more genetic diversity and greater litter size.
Due to polyandry, males can be confused by the identity of new offspring. Multiple mating by females and paternity confusion can decrease rates of infanticide. If the males are uncertain if the offspring are theirs, they are less likely to kill the offspring. | House mouse | Wikipedia | 474 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
Intrauterine insemination causes an evolutionary consequence resulting from polyandrous behavior. When multiple males mate with one female, there are multiple sets of sperm gametes in a female mouse. Offspring fertilized by multiple males can compete more strongly for mother's resources and can lead to a decrease in body size and variation in body size.
Inbreeding avoidance
Since inbreeding is detrimental, it tends to be avoided. In the house mouse, the major urinary protein (MUP) gene cluster provides a highly polymorphic scent signal of genetic identity that appears to underlie kin recognition and inbreeding avoidance. Thus there are fewer matings between mice sharing MUP haplotypes than would be expected if there were random mating. Another mechanism for avoiding inbreeding is evident when a female house mouse mates with multiple males. In such a case, there appears to be egg-driven sperm selection against sperm from related males.
Genetics
A region of mouse chromosome 16 is associated with thyroid function in mice. However, mice with a knockout of 16 genes - 550kb - in this region produced a normal phenotype, excluding these genes in particular from the dysfunction being pursued in that study.
Life expectancy
House mice usually live less than one year in the wild, due to a high level of predation and exposure to harsh environments. In protected environments, however, they often live two to three years. The Methuselah Mouse Prize is a competition to breed or engineer extremely long-lived laboratory mice. , the record holder was a genetically engineered mouse that lived for 1,819 days (7 days short of 5 years). Another record holder that was kept in an enriched environment but did not receive any genetic, pharmacological, or dietary treatment lived for 1,551 days ().
Aging | House mouse | Wikipedia | 369 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
In several different mouse strains, a significant increase was observed with age in 8-Oxo-2'-deoxyguanosine (8-oxo-dG) levels in nuclear DNA from liver, heart, brain, kidney, skeletal muscle and spleen. This increase in DNA damage was attributed to an age related increase in the sensitivity of these tissues to oxidative stress. Dietary restriction is known to increase the lifespan of rodents and to retard aging. Dietary restriction was found to significantly reduce the age-related accumulation of 8-oxo-dG levels in nuclear DNA of all tissues studied in mice. Thus it was suggested that oxidative DNA damages that arise from normal cellular metabolism could be highly relevant to aging and the diseases of aging. In another study, two types of DNA damage (8-hydroxy-2’-deoxyguanosine and DNA-protein crosslinks) were found to increase with age in mouse brain and liver.
Mice and humans
History
House mice usually live in proximity to humans, in or around houses or fields. They are native to India, and later they spread to the eastern Mediterranean about 13,000 BC, only spreading into the rest of Europe around 1000 BC. This time lag is thought to be because the mice require agrarian human settlements above a certain size. The house mouse first arrived in the Americas in the early sixteenth century. It was carried aboard on the ships of Spanish explorers and Conquistadors. About one hundred years later, it arrived in North America with French fur traders and English colonists. They have since been spread to all parts of the globe by humans.
Many studies have been done on mouse phylogenies to reconstruct early human movements. For example, one study suggests the possibility of a previously unsuspected early link between Northern Europe and Madeira on the basis of the origin of Madeiran mice. House mice were thought to be the primary reason for the domestication of cats.
As pets | House mouse | Wikipedia | 404 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
The first written reference to mice kept as pets occurs in the Erya, the oldest extant Chinese dictionary, from a mention in an 1100 BC version. Human domestication led to numerous strains of "fancy" or hobby mice with a variety of colours and a docile temperament. Domestic varieties of the house mouse are bred as a food source for some carnivorous pet reptiles, birds, arthropods, and fish. The effects of domestication can be rapid, with captive-reared mice differing in boldness and activity patterns compared to wild-caught mice after 4–5 generations in recent research.
Mice as pests
Mice are widespread pest organisms, and one of the most common rodents to infest human buildings. They commonly forage outdoors during the spring and summer, but retreat into buildings through the autumn and winter to seek warmth and food. They typically feed on unattended food, leftovers and garden produce. Their foraging risks the contamination and degradation of food supplies, and can also spread other pests such as fleas, ticks, lice and mites.
When infesting homes, house mice may pose a risk of damaging and compromising the structure of furniture and the building itself. They gnaw various materials to file down their growing teeth and keep the length under control. Common damage includes gnawed electrical wires, marks on wooden furniture and construction supporting elements, and textile damage.
Mice and diseases
House mice can sometimes transmit diseases, contaminate food, and damage food packaging. Although the Centers for Disease Control and Prevention provides a list with diseases transmitted by rodents, only a few of the diseases are transmitted through the house mouse.
Lymphocytic choriomeningitis (LCMV) can be transmitted by mice, but is not a commonly reported infection in humans, though most infections are mild and are often never diagnosed. Some concern exists that women should not be infected with LCMV during pregnancy.
House mice are not usually a vector of human plague (bubonic plague) because they have fewer infestations with fleas than do rats, and because the fleas which house mice normally carry exhibit little tendency to bite humans rather than their natural host. | House mouse | Wikipedia | 443 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
Rickettsialpox, caused by the bacterium Rickettsia akari and similar to chickenpox, is spread by mice in general, but is very rare and generally mild and resolves within two or three weeks if untreated. No known deaths have resulted from the disease. Murine typhus (also called endemic typhus), caused by the bacterium Rickettsia typhi, is transmitted by the fleas that infest rats. While rat fleas are the most common vectors, cat fleas and mouse fleas are less common modes of transmission. Endemic typhus is highly treatable with antibiotics. The U.S. CDC currently does not mention rickettsialpox or murine typhus on its website about diseases directly transmitted by rodents (in general).
Leptospirosis is carried by a variety of wild and domestic animals including dogs, rats, swine, cattle, mice in general, and can be transmitted by the urine of an infected animal and is contagious as long as the urine is still moist.
In Central Europe, the Dobriva sequence of hantavirus has been found in house mice. This is the most serious type of hanta that can infect humans.
Invasive species
Mice have become an invasive species on islands to where they have spread during the period of European exploration and colonisation.
New Zealand had no land mammals other than two species of bat prior to human occupation, and the house mouse is one of many species that have been introduced. Mice are responsible for a reduction in native bird species since they eat some of the same foods as birds. They are also known to kill lizards and have a large effect on native insects.
Gough Island in the South Atlantic is used by 20 species of seabirds for breeding, including almost all of the world's Tristan albatross (Diomedea dabbenena) and Atlantic petrel (Pterodroma incerta). Until house mice arrived on the island in the 19th century with sailors, the birds did not have any mammalian predators. The mice have since grown unusually large and have learned to attack albatross chicks, which can be 90 cm tall, but are largely immobile, by working in groups and gnawing on them until they bleed to death. | House mouse | Wikipedia | 463 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
In the grain belt of southeastern Australia, the introduced subspecies Mus musculus domesticus breed so successfully, every three years or so they reach plague proportions, achieving densities of 1000 per hectare and causing massive disruption to communities, and losses to agriculture of A$36 million annually.
As a model organism
Mice are the most commonly used mammalian laboratory animal, due to their relatively close relationship, and associated high homology, with humans, their ease in maintenance and handling, and their high rate of reproduction. Laboratory mice typically belong to standardized inbred strains selected for the stability or clarity of specific harmful mutations. This allows research with laboratory mice to easily restrict genetic and biological variables, making them very useful model organisms in genetic and medicinal research. Mice have been used in scientific research since the 1650s.
In folk culture
Importance of mice as a house and agricultural pest resulted in a development of a variety of mouse-related rituals and stories in world's cultures. The Ancient Egyptians had a story about "The mouse as vizier".
Many South Slavs had a traditional annual "Mouse Day" celebration. In the eastern Balkans (most of Bulgaria, North Macedonia, the Torlak districts of Serbia), the "Mouse Day" () was celebrated on October 9 of the Julian calendar (corresponds to October 27 of the Gregorian calendar in the 20th and 21st centuries), the next day after the feast of Saint Demetrius. In the western Balkans (Bosnia, Croatia), the Mouse Day would usually be celebrated in the spring, during the Maslenitsa week or early in the Lent. | House mouse | Wikipedia | 318 | 575890 | https://en.wikipedia.org/wiki/House%20mouse | Biology and health sciences | Rodents | Animals |
In mathematics, a parametric equation expresses several quantities, such as the coordinates of a point, as functions of one or several variables called parameters.
In the case of a single parameter, parametric equations are commonly used to express the trajectory of a moving point, in which case, the parameter is often, but not necessarily, time, and the point describes a curve, called a parametric curve. In the case of two parameters, the point describes a surface, called a parametric surface. In all cases, the equations are collectively called a parametric representation, or parametric system, or parameterization (alternatively spelled as parametrisation) of the object.
For example, the equations
form a parametric representation of the unit circle, where is the parameter: A point is on the unit circle if and only if there is a value of such that these two equations generate that point. Sometimes the parametric equations for the individual scalar output variables are combined into a single parametric equation in vectors:
Parametric representations are generally nonunique (see the "Examples in two dimensions" section below), so the same quantities may be expressed by a number of different parameterizations.
In addition to curves and surfaces, parametric equations can describe manifolds and algebraic varieties of higher dimension, with the number of parameters being equal to the dimension of the manifold or variety, and the number of equations being equal to the dimension of the space in which the manifold or variety is considered (for curves the dimension is one and one parameter is used, for surfaces dimension two and two parameters, etc.).
Parametric equations are commonly used in kinematics, where the trajectory of an object is represented by equations depending on time as the parameter. Because of this application, a single parameter is often labeled ; however, parameters can represent other physical quantities (such as geometric variables) or can be selected arbitrarily for convenience. Parameterizations are non-unique; more than one set of parametric equations can specify the same curve.
Implicitization
Converting a set of parametric equations to a single implicit equation involves eliminating the variable from the simultaneous equations This process is called . If one of these equations can be solved for , the expression obtained can be substituted into the other equation to obtain an equation involving and only: Solving to obtain and using this in gives the explicit equation while more complicated cases will give an implicit equation of the form
If the parametrization is given by rational functions | Parametric equation | Wikipedia | 495 | 576108 | https://en.wikipedia.org/wiki/Parametric%20equation | Mathematics | Basics | null |
where , , and are set-wise coprime polynomials, a resultant computation allows one to implicitize. More precisely, the implicit equation is the resultant with respect to of and .
In higher dimensions (either more than two coordinates or more than one parameter), the implicitization of rational parametric equations may by done with Gröbner basis computation; see .
To take the example of the circle of radius , the parametric equations
can be implicitized in terms of and by way of the Pythagorean trigonometric identity. With
and
we get
and thus
which is the standard equation of a circle centered at the origin.
Parametric plane curves
Parabola
The simplest equation for a parabola,
can be (trivially) parameterized by using a free parameter , and setting
Explicit equations
More generally, any curve given by an explicit equation
can be (trivially) parameterized by using a free parameter , and setting
Circle
A more sophisticated example is the following. Consider the unit circle which is described by the ordinary (Cartesian) equation
This equation can be parameterized as follows:
With the Cartesian equation it is easier to check whether a point lies on the circle or not. With the parametric version it is easier to obtain points on a plot.
In some contexts, parametric equations involving only rational functions (that is fractions of two polynomials) are preferred, if they exist. In the case of the circle, such a is
With this pair of parametric equations, the point is not represented by a real value of , but by the limit of and when tends to infinity.
Ellipse
An ellipse in canonical position (center at origin, major axis along the -axis) with semi-axes and can be represented parametrically as
An ellipse in general position can be expressed as
as the parameter varies from to . Here is the center of the ellipse, and is the angle between the -axis and the major axis of the ellipse.
Both parameterizations may be made rational by using the tangent half-angle formula and setting
Lissajous curve
A Lissajous curve is similar to an ellipse, but the and sinusoids are not in phase. In canonical position, a Lissajous curve is given by
where and are constants describing the number of lobes of the figure.
Hyperbola
An east-west opening hyperbola can be represented parametrically by
or, rationally
A north-south opening hyperbola can be represented parametrically as
or, rationally | Parametric equation | Wikipedia | 510 | 576108 | https://en.wikipedia.org/wiki/Parametric%20equation | Mathematics | Basics | null |
In all these formulae are the center coordinates of the hyperbola, is the length of the semi-major axis, and is the length of the semi-minor axis. Note that in the rational forms of these formulae, the points and , respectively, are not represented by a real value of , but are the limit of and as tends to infinity.
Hypotrochoid
A hypotrochoid is a curve traced by a point attached to a circle of radius rolling around the inside of a fixed circle of radius , where the point is at a distance from the center of the interior circle.
The parametric equations for the hypotrochoids are:
Some examples:
Parametric space curves
Helix
Parametric equations are convenient for describing curves in higher-dimensional spaces. For example:
describes a three-dimensional curve, the helix, with a radius of and rising by units per turn. The equations are identical in the plane to those for a circle.
Such expressions as the one above are commonly written as
where is a three-dimensional vector.
Parametric surfaces
A torus with major radius and minor radius may be defined parametrically as
where the two parameters and both vary between and .
As varies from to the point on the surface moves about a short circle passing through the hole in the torus. As varies from to the point on the surface moves about a long circle around the hole in the torus.
Straight line
The parametric equation of the line through the point and parallel to the vector is
Applications
Kinematics
In kinematics, objects' paths through space are commonly described as parametric curves, with each spatial coordinate depending explicitly on an independent parameter (usually time). Used in this way, the set of parametric equations for the object's coordinates collectively constitute a vector-valued function for position. Such parametric curves can then be integrated and differentiated termwise. Thus, if a particle's position is described parametrically as
then its velocity can be found as
and its acceleration as
Computer-aided design
Another important use of parametric equations is in the field of computer-aided design (CAD). For example, consider the following three representations, all of which are commonly used to describe planar curves.
Each representation has advantages and drawbacks for CAD applications. | Parametric equation | Wikipedia | 465 | 576108 | https://en.wikipedia.org/wiki/Parametric%20equation | Mathematics | Basics | null |
The explicit representation may be very complicated, or even may not exist. Moreover, it does not behave well under geometric transformations, and in particular under rotations. On the other hand, as a parametric equation and an implicit equation may easily be deduced from an explicit representation, when a simple explicit representation exists, it has the advantages of both other representations.
Implicit representations may make it difficult to generate points on the curve, and even to decide whether there are real points. On the other hand, they are well suited for deciding whether a given point is on a curve, or whether it is inside or outside of a closed curve.
Such decisions may be difficult with a parametric representation, but parametric representations are best suited for generating points on a curve, and for plotting it.
Integer geometry
Numerous problems in integer geometry can be solved using parametric equations. A classical such solution is Euclid's parametrization of right triangles such that the lengths of their sides and their hypotenuse are coprime integers. As and are not both even (otherwise and would not be coprime), one may exchange them to have even, and the parameterization is then
where the parameters and are positive coprime integers that are not both odd.
By multiplying and by an arbitrary positive integer, one gets a parametrization of all right triangles whose three sides have integer lengths.
Underdetermined linear systems
A system of linear equations in unknowns is underdetermined if it has more than one solution. This occurs when the matrix of the system and its augmented matrix have the same rank and . In this case, one can select unknowns as parameters and represent all solutions as a parametric equation where all unknowns are expressed as linear combinations of the selected ones. That is, if the unknowns are one can reorder them for expressing the solutions as
Such a parametric equation is called a of the solution of the system.
The standard method for computing a parametric form of the solution is to use Gaussian elimination for computing a reduced row echelon form of the augmented matrix. Then the unknowns that can be used as parameters are the ones that correspond to columns not containing any leading entry (that is the left most non zero entry in a row or the matrix), and the parametric form can be straightforwardly deduced. | Parametric equation | Wikipedia | 480 | 576108 | https://en.wikipedia.org/wiki/Parametric%20equation | Mathematics | Basics | null |
A squat toilet (or squatting toilet) is a toilet used by squatting, rather than sitting. This means that the posture for defecation and for female urination is to place one foot on each side of the toilet drain or hole and to squat over it. There are several types of squat toilets, but they all consist essentially of a toilet pan or bowl at floor level. Such a toilet pan is also called a "squatting pan". A squat toilet may use a water seal and therefore be a flush toilet, or it can be without a water seal and therefore be a dry toilet. The term "squat" refers only to the expected defecation posture and not any other aspects of toilet technology, such as whether it is water flushed or not.
Squat toilets are used all over the world, but are particularly common in some Asian and African nations, as well as in some Muslim countries. In many of those countries, anal cleansing with water is also the cultural norm and easier to perform than with toilets used in a sitting position. They are also occasionally found in some European and South American countries.
Squat toilets are regarded as traditional by many. In 1976, squatting toilets were said to be used by the majority of the world's population. However, there is a general trend in many countries to move from squatting toilets to sitting toilets (particularly in urban areas) as the latter are often regarded as more modern.
Design
Squat toilets are arranged at floor level, which requires the individual to squat with bent knees. In contrast to a pedestal or a sitting toilet, the opening of the drain pipe is located at the ground level.
Squatting slabs can be made of porcelain (ceramic), stainless steel, fibreglass, or in the case of low-cost versions in developing countries, with concrete, ferrocement, plastic, or wood covered with linoleum. Slabs can also be made of wood (timber), but need to be treated with preservatives, such as paint or linoleum, to prevent rotting and to enable thorough cleaning of the squatting slab.
There are two design variations: one where the toilet is level with the ground, and the other where it is raised on a platform approximately 30 cm (1 ft). The latter is easier to use for people who urinate while standing, but both types can be used for this purpose. There is also no difference for defecation or squatting urination.
Use | Squat toilet | Wikipedia | 498 | 576193 | https://en.wikipedia.org/wiki/Squat%20toilet | Technology | Hydraulics and pneumatics | null |
The user stands over the squat toilet facing the hood and pulls down (up in the case of skirts or dress) their trousers and underwear to the knees. The user then squats over the hole, as close to the front as possible, as excrement tends to fall onto the rear edge of the in-floor receptacle if the user squats too far back.
Health, hygiene and maintenance
The standing surface of the squatting pan should be kept clean and dry in order to prevent disease transmission and to limit odors.
Squat toilets are usually easier to clean than sitting toilets (pedestals), except that one has to bend down further if the squatting pan needs manual scrubbing. Squat toilets are properly cleaned using a mop in combination with a detergent solution.
Health effects
The squatting defecation posture is more physiological, ideal and relaxed. This is because it allows for better relaxation of the puborectalis muscle and hence straightening of the anorectal angle, and for faster, easier and more complete evacuation of stool. The squatting position therefore prevents excessive straining, and hence protects against stretching of the nerves, such as the pudendal nerve. Damage of these nerves can lead to permanent problems with urinary, defecation and sexual function. The squatting position also increases intra-abdominal pressure. The squatting position is often recommended as part of a range of measures to manage constipation and its sub-types, including obstructed defecation syndrome and dyssynergic defecation. Chronic, excessive straining during defecation, which is more likely to be needed in the sitting position, may be associated with the development of inflamed hemorrhoids or any of the spectrum of pelvic organ prolapse disorders, such as rectocele, rectal prolapse, etc.
However, according to some sources, excessive straining in the squatting position while defecating may increase the risk of severe hemorrhoids, or increase the tendency of prolapse of hemorrhoids, because of increased perineal descent and intra-abdominal pressure. Prolonged and repeated straining on a sitting toilet has the same effect.
Society and culture | Squat toilet | Wikipedia | 453 | 576193 | https://en.wikipedia.org/wiki/Squat%20toilet | Technology | Hydraulics and pneumatics | null |
Perceptions and trends
There are two different attitudes towards squat toilets, largely dependent on what users are used to, or whether the toilet is at a public or private place:
Some people regard squat toilets as more hygienic compared to sitting toilets. They might be easier to clean and there is no skin contact with the surface of the toilet seat. For that reason, some people perceive them as more hygienic, particularly for public toilets.
Some people regard sitting toilets as "more modern" than squat toilets. Sitting toilets have a lower risk of soiling clothing or shoes, as urine is less likely to splash on bottom parts of trousers or shoes. Furthermore, sitting toilets are more convenient for people with disabilities and the elderly.
A trend towards more sitting toilets in countries that were traditionally using squat toilets can be observed in some urban and more affluent areas, in areas with new buildings (as well as hotels and airports) or in tourist regions.
Public toilets
Squat toilets are used in public toilets, rather than household toilets, because they are perceived by some as easier to clean and more hygienic, therefore potentially more appropriate for general public use. For instance, this is the case in parts of France, Italy, Greece, or the Balkans, where such toilets are somewhat common in public toilets (restrooms).
Preferences by country or region | Squat toilet | Wikipedia | 269 | 576193 | https://en.wikipedia.org/wiki/Squat%20toilet | Technology | Hydraulics and pneumatics | null |
The following general statements can be made:
Squat toilets are common in many Asian countries, including China and India. They are also widespread in Turkey (), Nepal, Indonesia, Bangladesh, Pakistan, Sri Lanka, Malaysia, Myanmar, The Philippines, Iran and Iraq. They can be found in nations like Japan, South Korea, Thailand, and Singapore.
People in sub-Saharan African countries, especially in rural areas, widely use squat toilets, for example in Kenya, Rwanda, Somalia, Tanzania, and Uganda. Squat toilets are not common in South Africa.
Much of the world's population use squat toilets, especially in rural areas of developing countries.
Countries in the Middle East and North Africa often have both types of toilets, i.e. sitting and squatting.
In Hindu or Muslim cultures, the prevalence of squat toilets is generally quite high, as is the practice of anal cleansing with water.
In Latin and South America, flush toilets are always of the sitting type, whereas dry toilets may be either of the sitting or a squatting type. The occurrence of squat toilets in urban areas of Latin America appears to be rather low.
Squat toilets are rare in Australia, New Zealand, United States, Canada, and countries in Northern and Western Europe (except public toilets in France). Where they do exist, they have usually been installed to accommodate visitors, tourists, students, or recent migrants from places that use squatting toilets traditionally.
Europe
In Southern and Eastern Europe including parts of France, in Turkey, Greece, Italy, Albania, Balkans, and Russia they are common, especially in public toilets. Squat pit latrine toilets are still present in many areas of Russia.
Squat toilets are generally non-existent in Northern and Western Europe. France and Italy are an exception and have some squat toilets remaining in old buildings and public toilets because they used to be the norm there in the early 20th century. In BMW Welt in Munich, the public restrooms have some stalls with squat toilets. There are also a few squat toilets at Stuttgart Airport.
China
Many areas in China have traditional squat toilets instead of sitting toilets, especially in public toilets. Nevertheless, sitting toilets have increasingly become the norm in major urban areas and cities. Sitting toilets are on the one hand associated with development and modernization, and on the other hand with reduced hygiene and possible transmission of diseases.
Japan | Squat toilet | Wikipedia | 472 | 576193 | https://en.wikipedia.org/wiki/Squat%20toilet | Technology | Hydraulics and pneumatics | null |
Although in Japan it is believed that the squat toilet is traditional, the trend in Japan is to move away from squat toilets: According to Toto, one of Japan's major toilet manufacturers, the production of Western-style toilets increased rapidly since 1976. In 2015, only 1% of all toilets produced by this company were squat toilets.
Since the 1960s, the trend has been to replace squat toilets at schools and public places with sitting toilets. This trend was thought to accelerate in the run-up to the 2020 Summer Olympics in Tokyo.
Since the 1980s, high-tech sitting toilets are emerging that replace traditional squat toilets, especially in urban areas. However, many rural people have no experience with such high-tech toilets and need detailed instructions. High-tech sitting toilets have also become commonplace in South Korea.
Gallery | Squat toilet | Wikipedia | 163 | 576193 | https://en.wikipedia.org/wiki/Squat%20toilet | Technology | Hydraulics and pneumatics | null |
Philodendron is a large genus of flowering plants in the family Araceae. , the Plants of the World Online accepted 621 species; other sources accept different numbers. Regardless of number of species, the genus is the second-largest member of the family Araceae, after genus Anthurium. Taxonomically, the genus Philodendron is still poorly known, with many undescribed species. Many are grown as ornamental and indoor plants. The name derives from the Greek words philo- 'love, affection' and dendron 'tree'. The generic name, Philodendron, is often used as the English name.
Description
Growth habit
Compared to other genera of the family Araceae, philodendrons have an extremely diverse array of growth methods. The habits of growth can be epiphytic, hemiepiphytic, or rarely terrestrial. Others can show a combination of these growth habits depending on the environment. Hemiepiphytic philodendrons can be classified into two types: primary and secondary hemiepiphytes. A primary hemiepiphytic philodendron starts life high up in the canopy where the seed initially sprouts. The plant then grows as an epiphyte. Once it has reached a sufficient size and age, it will begin producing aerial roots that grow toward the forest floor. Once they reach the forest floor, nutrients can be obtained directly from the soil. In this manner, the plant's strategy is to obtain light early in its life at the expense of nutrients. Some primary epiphytic species have a symbiotic relationship with ants. In these species, the ants' nest is grown amongst the plant's roots, which help keep the nest together. Philodendrons have extrafloral nectaries, glands that secrete nectar to attract the ants. The philodendron, in turn, obtains nutrients from the surrounding ant nest, and the aggressive nature of the ants serves to protect the plant from other insects which would eat it. | Philodendron | Wikipedia | 418 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
Secondary hemiepiphytes start life on the ground or on part of a tree trunk very close to the ground, where the seeds sprout. These philodendrons have their roots in the ground early in their lives. They then begin climbing up a tree and eventually may become completely epiphytic, doing away with their subterranean roots. Secondary hemiepiphytes do not always start their lives close to a tree. For these philodendrons, the plant will grow with long internodes along the ground until a tree is found. They find a suitable tree by growing towards darker areas, such as the dark shadow of a tree. This trait is called scototropism. After a tree has been found, the scototropic behavior stops and the philodendron switches to a phototropic growth habit and the internodes shorten and thicken. Usually, however, philodendrons germinate on trees. | Philodendron | Wikipedia | 194 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
A few species show three peaks in temperature during flowering, which stimulates beetles within the spathe and increasing the likelihood they will be sufficiently coated with pollen. A sticky resin is also produced in drops attached to the spadix which help to keep the pollen attached to the beetles. This resin producing quality is unique to Philodendron and Monstera, as other genera of Araceae do not produce it on their spadices. The resin is also found on the stems, leaves, and roots of philodendrons. Its color can be red, orange, yellow, or colorless when it is first produced. Yet, over time, it will turn brown as it is exposed to air. Also, some evidence suggests the thermogenesis triggers the beetles to mate. It also appears to distribute the pheromones into the air. The reason for the spadix being held at 45° relative to the spathe may be to maximize the heat's ability to waft the pheromones into the air. Oxidizing stored carbohydrates and lipids has been found to be the energy source for thermogenesis. The part of the spadix that heats up is the sterile zone. As it heats up, carbohydrates are used, but once the spadix has reached its maximum temperature, lipids are oxidized. The lipids are not first converted to carbohydrates, but rather are directly oxidized. The thermogenic reaction is triggered when concentrations of acetosalicytic acid form in the sterile zone. The acid sets off the mitochondria in the cells that make up the sterile zone to switch to an electron transport chain called the cyanide-resistant pathway, which results in the production of heat. Philodendrons consume oxygen during thermogenesis. The rate at which oxygen is used is remarkably high, close to that of hummingbirds and sphinx moths. The spadix has been shown to generate infrared radiation.
Leaves | Philodendron | Wikipedia | 413 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
The leaves are usually large and imposing, often lobed or deeply cut, and may be more or less pinnate. They can also be oval (Philodendron 'White Princess'), spear-shaped, divided (Philodendron tripartitum) or in many other possible shape variations. The leaves are borne alternately on the stem. A quality of philodendrons is that they do not have a single type of leaf on the same plant. Instead, they have juvenile leaves and adult leaves, which can be drastically different from one another. The leaves of seedling philodendrons are usually heart-shaped early in the life of the plant. But after it has matured past the seedling stage, the leaves will acquire the typical juvenile leaf's shape and size. Later in the philodendron's life, it starts producing adult leaves, a process called metamorphosis. Most philodendrons go through metamorphosis gradually; there is no immediately distinct difference between juvenile and adult leaves. Aside from being typically much bigger than the juvenile leaves, the shape of adult leaves can be significantly different. In fact, considerable taxonomic difficulty has occurred in the past due to these differences, causing juvenile and adult plants to mistakenly be classified as different species.
The trigger for the transformation to adult leaves can vary considerably. One possible trigger is the height of the plant. Secondary hemiepiphytes start off on the dark forest floor and climb their way up a tree, displaying their juvenile type leaves along the way. Once they reach a sufficient height, they begin developing adult type leaves. The smaller juvenile leaves are used for the darker forest floor where light is in scarce supply, but once they reach a sufficient height in the canopy the light is bright enough that the bigger adult leaves can serve a useful purpose. Another possible trigger occurs in primary hemiepiphytes. These philodendrons typically send their aerial roots downward. Once their roots have reached the ground below, the plant will begin taking up nutrients from the soil, of which it had been previously deprived. As a result, the plant will quickly morph into its adult leaves and gain in size dramatically. Another quality of philodendrons leaves is they are often quite different in shape and size even between two plants of the same species. As a result of all these different possible leaf shapes, it is often difficult to differentiate natural variations from morphogenesis. | Philodendron | Wikipedia | 496 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
Cataphylls
Philodendrons also produce cataphylls, which are modified leaves that surround and protect the newly forming leaves. Cataphylls are usually green, leaf-like, and rigid while they are protecting the leaf. In some species, they can even be rather succulent. Once the leaf has been fully formed, the cataphyll usually remains attached where the stem and base of the leaf meet. In philodendrons, cataphylls typically fall into two categories: deciduous and persistent types. A deciduous cataphyll curls away from the leaf once it has formed, eventually turning brown and drying out, and finally falling off the plant, leaving a scar on the stem where it was attached. Deciduous cataphylls are typically found on vining philodendrons, whereas persistent cataphylls are typical of epiphytic philodendrons or appressed climbers. In the latter, the cataphylls are prevented from falling off in a timely manner due to the short internodes of the plant. The cataphylls will remain attached, drying out and becoming nothing more than fibers attached at the nodes. In some philodendrons, the cataphylls build up over time and eventually form a wet mass at the nodes. This may keep emerging roots moist and provide some form of lubrication to new leaves. | Philodendron | Wikipedia | 283 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
Roots
Philodendrons have both aerial and subterranean roots. The aerial roots occur in many shapes and sizes and originate from most of the plant's nodes or occasionally from an internode. The size and number of aerial roots per node depends on the presence of a suitable substrate for the roots to attach themselves. Aerial roots serve two primary purposes. They allow the philodendron to attach itself to a tree or other plant, and they allow it to collect water and nutrients. As such, the roots are divided morphologically into these two categories. Aerial roots used for attaching to trees tend to be shorter, more numerous, and sometimes have a layer of root hairs attached; those used for collecting water and nutrients tend to be thicker and longer. These feeder roots tend to attach flush with the substrate to which the philodendron is attached, and make their way directly downwards in search of soil. In general, feeder roots tend to show both positive hydrotropic and negative heliotropic behaviors. Characteristic of roots in philodendrons is the presence of a sclerotic hypodermis, which are cylindrical tubes inside the epidermis that can be one to five cells long. The cells that line the sclerotic hypodermis are elongated and tend to be hardened. Underneath the epidermis is a unique layer of cells in a pattern of long cells followed by short cells.
Extrafloral nectaries
Some philodendrons have extrafloral nectaries (nectar-producing glands found outside of the flowers). The nectar attracts ants, with which the plant enjoys a protective symbiotic relationship. Nectaries can be found in a variety of locations on the plant, including the stalks, sheaths, lower surfaces of the leaves, and spathes. The nectaries produce a sweet, sticky substance the ants like to eat and which provides an incentive for them to build their nests amongst the roots of the given philodendron. In some cases, the amount of nectar produced can be quite extensive, resulting in the surface becoming entirely covered with it.
Reproduction
Sexual | Philodendron | Wikipedia | 424 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
When philodendrons are ready to reproduce, they will produce an inflorescence which consists of a leaf-like hood called a spathe within which is enclosed a tube-like structure called a spadix. Depending on the species, a single inflorescence can be produced or a cluster of up to 11 inflorescences can be produced at a single time on short peduncles. The spathe tends to be waxy and is usually bicolored. In some philodendrons, the color of the base of the spathe contrasts in color with the upper part, and in others, the inner and outer surfaces of the spathe differ in coloration. The paler color tends to be either white or green, and the darker usually red or crimson. Pelargonidin is the predominant pigment causing the red coloration in the spathes. The upper portion of the spathe is called the limb or blade, while the lower portion is called the convolute tube or chamber due to its tubular structure at the base. The spadix is more often than not white and shorter than the spathe. On the spadix are found fertile female, fertile male, and sterile male flowers. The fertile male and female flowers are separated on the spadix by a sterile zone or staminodal region composed of sterile male flowers. This barrier of sterile male flowers ensures fertile male flowers do not fertilize the female flowers. The arrangement tends to be vertical, with fertile male flowers at the top of the spadix followed by sterile male flowers, and fertile female flowers very close to the bottom in the region known as the spathe tube or chamber. In some philodendrons, an additional region of sterile male flowers is found at the very top of the spadix. The fertile female flowers are often not receptive to fertilization when the fertile males are producing pollen, which again prevents self-pollination. The pollen itself is thread-like and appears to project out from the region where the fertile male flowers are located. | Philodendron | Wikipedia | 419 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
Sexual reproduction is achieved by means of beetles, with many philodendron species requiring the presence of a specific beetle species to achieve pollination. The reverse is not always the case, as many beetle species will pollinate more than one philodendron species. These same beetles could also pollinate other genera outside of philodendron, as well as outside of the family Araceae. The pollinating beetles are males and members of the subfamily Rutelinae and Dynastinae, and to date the only beetles seen to pollinate the inflorescence are in the genera Cyclocephala or Erioscelis. Other smaller types of beetles in the genus Neelia visit the inflorescences, as well, but they are not believed to be involved in pollinating philodendrons. To attract the beetles, the sterile male flowers give off pheromones to attract the male beetles, usually at dusk. This process, female anthesis, is followed by male anthesis, in which the pollen is produced. Female anthesis typically lasts up to two days and includes the gradual opening of the spathe to allow the beetles to enter. Some evidence suggests the timing of opening of the spathe is dependent on light levels, where cloudy, darker days result in the spathe opening up earlier than on clear days. During female anthesis, the spadix will project forward at roughly 45° relative to the spathe. | Philodendron | Wikipedia | 292 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
Once female anthesis is nearing its end and the female flowers have been pollinated, the spathe will be fully open and male anthesis begins. In the beginning of male anthesis, the fertile male flowers complete the process of producing the pollen and the female flowers become unreceptive to further pollination. Additionally, the spadix moves from its 45° position and presses up flush to the spathe. Towards the end of male anthesis, the spathe begins to close from the bottom, working its way up and forcing the beetles to move up and across the upper region of the spathe, where the fertile male flowers are located. In doing so, the philodendron controls when the beetles come and when they leave and forces them to rub against the top of the spadix where the pollen is located as they exit, thus ensuring they are well-coated with pollen. One would expect the beetles to stay indefinitely if they could due to the very favorable conditions the inflorescence provides. After male anthesis, the males will go off and find another philodendron undergoing female anthesis, so will pollinate the female flowers with the pollen it had collected from its previous night of mating.
Fruit
Botanically, the fruit produced is a berry. The berries develop later in the season; berry development time varies from species to species from a few weeks to a year, although most philodendrons take a few months. The spathe will enlarge to hold the maturing berries. Once the fruit are mature, the spathe will begin to open again, but this time it will break off at the base and fall to the forest floor. Additionally, the berries are edible, although they contain calcium oxalate crystals, and have a taste akin to bananas. Many botanical sources will indicate that the berries are poisonous, probably due to the oxalate crystals. Many tropical plants contain oxalates in varying amounts. Sometimes proper preparation can render these harmless, and in many cases eating minor amounts causes most people no distress or minor gastric irritation. However, care should be taken to verify the toxicity of any particular species before ingesting these berries, particularly regularly or in large amounts. | Philodendron | Wikipedia | 446 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
The color of the berries can vary depending on the species, but most produce a white berry with slight tones of green. Some produce orange berries and others yellow berries, though. Still others will produce berries that start off white, but then change to another color with time. Philodendrons that produce orange berries tend to be members of the section Calostigma. Contained within the berries are the seeds which are extremely small compared to other members of the family Araceae. The berries often give off odors to attract animals to eat and disperse them. For example, Philodendron alliodorum berries are known to emit an odor similar to that of garlic. The animals that distribute the seeds depends on the species, but some possible dispersers include bats and monkeys. Insects also may be responsible for dispersing seeds, as beetles and wasps have been seen feeding on philodendron berries.
Eurytomid wasps also seek out philodendrons and are known to lay their eggs in the ovaries of many Philodendron species, resulting in galled inflorescences.
Hybridization
Philodendrons exhibit extremely few physical reproductive barriers to prevent hybridization, but very few natural hybrids are found in nature. This may be because philodendrons have many geographic and time barriers to prevent any such cross pollination. For example, it is rare for more than one philodendron species to be flowering at the same time or to be pollinated by the same species of beetles. The beetles have also been observed to be selective to the height of the plant they pollinate, which would serve as an additional preventive measure to make hybrids less likely. Because of these outside barriers, philodendrons may not have had to evolve physical mechanisms to prevent cross-pollination. Hybrids in nature are only rarely reported. When found, these hybrids often can show remarkable genetic relationships. Crosses between two philodendrons in different sections can occur successfully.
Taxonomy | Philodendron | Wikipedia | 401 | 576200 | https://en.wikipedia.org/wiki/Philodendron | Biology and health sciences | Monocots | null |
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