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Genus Hemicentetes
Highland streaked tenrec (Hemicentetes nigriceps)
Lowland streaked tenrec (Hemicentetes semispinosus)
Genus Tenrec
Common tenrec (Tenrec ecaudatus) | Tenrec | Wikipedia | 51 | 312933 | https://en.wikipedia.org/wiki/Tenrec | Biology and health sciences | Other afrotheres | Animals |
The Pinaceae (), or pine family, are conifer trees or shrubs, including many of the well-known conifers of commercial importance such as cedars, firs, hemlocks, piñons,
larches, pines and spruces. The family is included in the order Pinales, formerly known as Coniferales. Pinaceae have distinctive cones with woody scales bearing typically two ovules, and are supported as monophyletic by both morphological trait and genetic analysis. They are the largest extant conifer family in species diversity, with between 220 and 250 species (depending on taxonomic opinion) in 11 genera, and the second-largest (after Cupressaceae) in geographical range, found in most of the Northern Hemisphere, with the majority of the species in temperate climates, but ranging from subarctic to tropical. The family often forms the dominant component of boreal, coastal, and montane forests. One species, Pinus merkusii, grows just south of the equator in Southeast Asia. Major centres of diversity are found in the mountains of southwest China, Mexico, central Japan, and California.
Description
Members of the family Pinaceae are trees (rarely shrubs) growing from tall, mostly evergreen (except the deciduous Larix and Pseudolarix), resinous, monoecious, with subopposite or whorled branches, and spirally arranged, linear (needle-like) leaves. The embryos of Pinaceae have three to 24 cotyledons.
The female cones are large and usually woody, long, with numerous spirally arranged scales, and two winged seeds on each scale. The male cones are small, long, and fall soon after pollination; pollen dispersal is by wind. Seed dispersal is mostly by wind, but some species have large seeds with reduced wings, and are dispersed by birds. Analysis of Pinaceae cones reveals how selective pressure has shaped the evolution of variable cone size and function throughout the family. Variation in cone size in the family has likely resulted from the variation of seed dispersal mechanisms available in their environments over time. All Pinaceae with seeds weighing less than 90 milligrams are seemingly adapted for wind dispersal. Pines having seeds larger than 100 mg are more likely to have benefited from adaptations that promote animal dispersal, particularly by birds. Pinaceae that persist in areas where tree squirrels are abundant do not seem to have evolved adaptations for bird dispersal. | Pinaceae | Wikipedia | 489 | 312940 | https://en.wikipedia.org/wiki/Pinaceae | Biology and health sciences | Pinaceae | Plants |
Boreal conifers have many adaptions for winter. The narrow conical shape of northern conifers, and their downward-drooping limbs help them shed snow, and many of them seasonally alter their biochemistry to make them more resistant to freezing, called "hardening".
Classification
Classification of the subfamilies and genera of Pinaceae has been subject to debate in the past. Pinaceae ecology, morphology, and history have all been used as the basis for methods of analyses of the family. An 1891 publication divided the family into two subfamilies, using the number and position of resin canals in the primary vascular region of the young taproot as the primary consideration. In a 1910 publication, the family was divided into two tribes based on the occurrence and type of long–short shoot dimorphism.
A more recent classification divided the subfamilies and genera based on the consideration of features of ovulate cone anatomy among extant and fossil members of the family. Below is an example of how the morphology has been used to classify Pinaceae.
The 11 genera are grouped into four subfamilies, based on the microscopical anatomy and the morphology of the cones, pollen, wood, seeds, and leaves: | Pinaceae | Wikipedia | 250 | 312940 | https://en.wikipedia.org/wiki/Pinaceae | Biology and health sciences | Pinaceae | Plants |
Subfamily Pinoideae (Pinus): cones are biennial, rarely triennial, with each year's scale-growth distinct, forming an umbo on each scale, the cone scale base is broad, concealing the seeds fully from abaxial (below the phloem vessels) view, the seed is without resin vesicles, the seed wing holds the seed in a pair of claws, leaves have primary stomatal bands adaxial (above the xylem) or equally on both surfaces.
Subfamily Piceoideae (Picea): cones are annual, without a distinct umbo, the cone scale base is broad, concealing the seeds fully from abaxial view, seed is without resin vesicles, blackish, the seed wing holds the seed loosely in a cup, leaves have primary stomatal bands adaxial (above the xylem) or equally on both surfaces.
Subfamily Laricoideae (Larix, Pseudotsuga, and Cathaya): cones are annual, without a distinct umbo, the cone scale base is broad, concealing the seeds fully from abaxial view, the seed is without resin vesicles, whitish, the seed wing holds the seed tightly in a cup, leaves have primary stomatal bands abaxial only.
Subfamily Abietoideae (Abies, Cedrus, Pseudolarix, Keteleeria, Nothotsuga, and Tsuga): cones are annual, without a distinct umbo, the cone scale base is narrow, with the seeds partly visible in abaxial view, the seed has resin vesicles, the seed wing holds the seed tightly in a cup, leaves have primary stomatal bands abaxial only.
Phylogeny
A revised 2018 phylogeny places Cathaya as sister to the pines rather than in the Laricoidae subfamily with Larix and Pseudotsuga.
Multiple molecular studies indicate that in contrast to previous classifications placing it outside the conifers, Gnetophyta may in fact be the sister group to the Pinaceae, with both lineages having diverged during the early-mid Carboniferous. This is known as the "gnepine" hypothesis. | Pinaceae | Wikipedia | 459 | 312940 | https://en.wikipedia.org/wiki/Pinaceae | Biology and health sciences | Pinaceae | Plants |
Evolutionary history
Pinaceae is estimated to have diverged from other conifer groups during the late Carboniferous ~313 million years ago. Various possible stem-group relatives have been reported from as early as the Late Permian (Lopingian) The extinct conifer cone genus Schizolepidopsis likely represent stem-group members of the Pinaceae, the first good records of which are in the Middle-Late Triassic, with abundant records during the Jurassic across Eurasia. The oldest crown group (descendant of the last common ancestor of all living species) member of Pinaceae is the cone Eathiestrobus, known from the Upper Jurassic (lower Kimmeridgian, 157.3-154.7 million years ago) of Scotland, which likely belongs to the pinoid grouping of the family. Pinaceae rapidly radiated during the Early Cretaceous. Members of the modern genera Pinus (pines), Picea (spruce) and Cedrus (cedar) first appear during the Early Cretaceous. The extinct Cretaceous genera Pseudoaraucaria and Obirastrobus appear to be members of Abietoideae, while Pityostrobus appears to be non-monophyletic, containing many disparately related members of Pinaceae. While Pinaceae, and indeed all of its subfamilies, substantially predate the break up of the super-continent Pangea, its distribution was limited to northern Laurasia. During the Cenozoic, Pinaceae had higher rates of species turnover than Southern Hemisphere conifers, thought to be driven by range shifts in response to glacial cycles.
Defense mechanisms
External stresses on plants have the ability to change the structure and composition of forest ecosystems. Common external stress that Pinaceae experience are herbivore and pathogen attack which often leads to tree death. In order to combat these stresses, trees need to adapt or evolve defenses against these stresses. Pinaceae have evolved myriad mechanical and chemical defenses, or a combination of the two, in order to protect themselves against antagonists. Pinaceae have the ability to up-regulate a combination of constitutive mechanical and chemical strategies to further their defenses.
Pinaceae defenses are prevalent in the bark of the trees. This part of the tree contributes a complex defensive boundary against external antagonists. Constitutive and induced defenses are both found in the bark. | Pinaceae | Wikipedia | 475 | 312940 | https://en.wikipedia.org/wiki/Pinaceae | Biology and health sciences | Pinaceae | Plants |
Constitutive defenses
Constitutive defenses are typically the first line of defenses used against antagonists and can include sclerified cells, lignified periderm cells, and secondary compounds such as phenolics and resins. Constitutive defenses are always expressed and offer immediate protection from invaders but could also be defeated by antagonists that have evolved adaptations to these defense mechanisms. One of the common secondary compounds used by Pinaceae are phenolics or polyphenols. These secondary compounds are preserved in vacuoles of polyphenolic parenchyma cells (PP) in the secondary phloem.
Induced defenses
Induced defense responses need to be activated by certain cues, such as herbivore damage or other biotic signals.
A common induced defense mechanism used by Pinaceae is resins. Resins are also one of the primary defenses used against attack. Resins are short term defenses that are composed of a complex combination of volatile mono- (C10) and sesquiterpenes (C15) and nonvolatile diterpene resin acids (C20). They are produced and stored in specialized secretory areas known as resin ducts, resin blisters, or resin cavities. Resins have the ability to wash away, trap, fend off antagonists, and are also involved in wound sealing. They are an effective defense mechanism because they have toxic and inhibitory effects on invaders, such as insects or pathogens. Resins could have developed as an evolutionary defense against bark beetle attacks. One well researched resin present in Pinaceae is oleoresin. Oleoresin had been found to be a valuable part of the conifer defense mechanism against biotic attacks. They are found in secretory tissues in tree stems, roots, and leaves. Oleoresin is also needed in order to classify conifers.
Active research: methyl jasmonate
The topic of defense mechanisms within family Pinaceae is a very active area of study with numerous studies being conducted. Many of these studies use methyl jasmonate (MJ) as an antagonist. Methyl jasmonate is known to be able to induce defense responses in the stems of multiple Pinaceae species. It has been found that MJ stimulated the activation of PP cells and formation of xylem traumatic resin ducts (TD). These are structures that are involved in the release of phenolics and resins, both forms of defense mechanism. | Pinaceae | Wikipedia | 504 | 312940 | https://en.wikipedia.org/wiki/Pinaceae | Biology and health sciences | Pinaceae | Plants |
A blacklight, also called a UV-A light, Wood's lamp, or ultraviolet light, is a lamp that emits long-wave (UV-A) ultraviolet light and very little visible light. One type of lamp has a violet filter material, either on the bulb or in a separate glass filter in the lamp housing, which blocks most visible light and allows through UV, so the lamp has a dim violet glow when operating. Blacklight lamps which have this filter have a lighting industry designation that includes the letters "BLB". This stands for "blacklight blue". A second type of lamp produces ultraviolet but does not have the filter material, so it produces more visible light and has a blue color when operating. These tubes are made for use in "bug zapper" insect traps, and are identified by the industry designation "BL". This stands for "blacklight".
Blacklight sources may be specially designed fluorescent lamps, mercury-vapor lamps, light-emitting diodes (LEDs), lasers, or incandescent lamps. In medicine, forensics, and some other scientific fields, such a light source is referred to as a Wood's lamp, named after Robert Williams Wood, who invented the original Wood's glass UV filters.
Although many other types of lamp emit ultraviolet light with visible light, blacklights are essential when UV-A light without visible light is needed, particularly in observing fluorescence, the colored glow that many substances emit when exposed to UV. They are employed for decorative and artistic lighting effects, diagnostic and therapeutic uses in medicine, the detection of substances tagged with fluorescent dyes, rock-hunting, scorpion-hunting, the detection of counterfeit money, the curing of plastic resins, attracting insects and the detection of refrigerant leaks affecting refrigerators and air conditioning systems. Strong sources of long-wave ultraviolet light are used in tanning beds.
Medical hazard
UV-A presents a potential hazard when eyes and skin are exposed, especially to high power sources. According to the World Health Organization, UV-A is responsible for the initial tanning of skin and it contributes to skin ageing and wrinkling. UV-A may also contribute to the progression of skin cancers. Additionally, UV-A can have negative effects on eyes in both the short-term and long-term.
Types
Fluorescent | Blacklight | Wikipedia | 482 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
Fluorescent blacklight tubes are typically made in the same fashion as normal fluorescent tubes except that a phosphor that emits UVA light instead of visible white light is used on the inside of the tube. The type most commonly used for blacklights, designated blacklight blue or "BLB" by the industry, has a dark blue filter coating on the tube, which filters out most visible light, so that fluorescence effects can be observed. These tubes have a dim violet glow when operating. They should not be confused with "blacklight" or "BL" tubes, which have no filter coating, and have a brighter blue color. These are made for use in "bug zapper" insect traps where the emission of visible light does not interfere with the performance of the product. The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoride (:) or europium-doped strontium borate (:) while the phosphor used to produce a peak around 350 to 353 nanometres is lead-doped barium silicate (:). "Blacklight blue" lamps peak at 365 nm.
Manufacturers use different numbering systems for blacklight tubes. Philips' is becoming outdated (as of 2010), while the (German) Osram system is becoming dominant outside North America. The following table lists the tubes generating blue, UVA and UVB, in order of decreasing wavelength of the most intense peak. Approximate phosphor compositions, major manufacturer's type numbers and some uses are given as an overview of the types available. "Peak" position is approximated to the nearest 10 nm. "Width" is the measure between points on the shoulders of the peak that represent 50% intensity.
Bug zappers | Blacklight | Wikipedia | 379 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
Another class of UV fluorescent bulb is designed for use in bug zappers. Insects are attracted to the UV light, which they are able to see, and are then electrocuted by the device. These bulbs use the same UV-A emitting phosphor blend as the filtered blacklight, but since they do not need to suppress visible light output, they do not use a purple filter material in the bulb. Plain glass blocks out less of the visible mercury emission spectrum, making them appear light blue-violet to the naked eye. These lamps are referred to by the designation "blacklight" or "BL" in some North American lighting catalogs. These types are not suitable for applications which require the low visible light output of "BLB" tubes lamps.
Incandescent
A blacklight may also be formed by simply using a UV filter coating such as Wood's glass on the envelope of a common incandescent bulb. This was the method that was used to create the very first blacklight sources. Although incandescent bulbs are a cheaper alternative to fluorescent tubes, they are exceptionally inefficient at producing UV light since most of the light emitted by the filament is visible light which must be blocked. Due to its black body spectrum, an incandescent light radiates less than 0.1% of its energy as UV light. Incandescent UV bulbs, due to the necessary absorption of the visible light, become very hot during use. This heat is, in fact, encouraged in such bulbs, since a hotter filament increases the proportion of UVA in the black-body radiation emitted. This high running-temperature reduces the life of the lamp from a typical 1,000 hours to around 100 hours.
Mercury vapor | Blacklight | Wikipedia | 358 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
High-power mercury vapor blacklight lamps are made in power ratings of 100 to 1,000 watts. These do not use phosphors, but rely on the intensified and slightly broadened 350–375 nm spectral line of mercury from high pressure discharge at between , depending upon the specific type. These lamps use envelopes of Wood's glass or similar optical filter coatings to block out all the visible light and also the short wavelength (UVC) lines of mercury at 184.4 and 253.7 nm, which are harmful to the eyes and skin. A few other spectral lines, falling within the pass band of the Wood's glass between 300 and 400 nm, contribute to the output.
These lamps are used mainly for theatrical purposes and concert displays. They are more efficient UVA producers per unit of power consumption than fluorescent tubes.
LED
Ultraviolet light can be generated by some light-emitting diodes, but wavelengths shorter than 380 nm are uncommon, and the emission peaks are broad, so only the very lowest energy UV photons are emitted, within predominant not visible light.
Safety
Although blacklights produce light in the UV range, their spectrum is mostly confined to the longwave UVA region, that is, UV radiation nearest in wavelength to visible light, with low frequency and therefore relatively low energy. While low, there is still some power of a conventional blacklight in the UVB range. UVA is the safest of the three spectra of UV light, although high exposure to UVA has been linked to the development of skin cancer in humans. The relatively low energy of UVA light does not cause sunburn. It can damage collagen fibers, so may accelerate skin aging and cause wrinkles. It can also degrade vitamin A in the skin. | Blacklight | Wikipedia | 358 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
UVA light has been shown to cause DNA damage, but not directly, like UVB and UVC. Due to its longer wavelength, it is absorbed less and reaches deeper into skin layers, where it produces reactive chemical intermediates such as hydroxyl and oxygen radicals, which in turn can damage DNA and result in a risk of melanoma. The weak output of blacklights is not sufficient to cause DNA damage or cellular mutations in the way that direct summer sunlight can, although there are reports that overexposure to the type of UV radiation used for creating artificial suntans on sunbeds can cause DNA damage, photo-aging (damage to the skin from prolonged exposure to sunlight), toughening of the skin, suppression of the immune system, cataract formation and skin cancer.
UV-A can have negative effects on eyes in both the short-term and long-term.
Uses
Ultraviolet radiation is invisible to the human eye, but illuminating certain materials with UV radiation causes the emission of visible light, causing these substances to glow with various colors. This is called fluorescence, and has many practical uses. Blacklights are required to observe fluorescence, since other types of ultraviolet lamps emit visible light which drowns out the dim fluorescent glow.
Medical applications
A Wood's lamp is a diagnostic tool used in dermatology by which ultraviolet light is shone (at a wavelength of approximately 365 nanometers) onto the skin of the patient; a technician then observes any subsequent fluorescence. For example, porphyrins—associated with some skin diseases—will fluoresce pink. Though the technique for producing a source of ultraviolet light was devised by Robert Williams Wood in 1903 using "Wood's glass", it was in 1925 that the technique was used in dermatology by Margarot and Deveze for the detection of fungal infection of hair. It has many uses, both in distinguishing fluorescent conditions from other conditions and in locating the precise boundaries of the condition.
Fungal and bacterial infections
It is also helpful in diagnosing:
Fungal infections. Some forms of tinea, such as Trichophyton tonsurans, do not fluoresce.
Bacterial infections
Corynebacterium minutissimum is coral red
Pseudomonas is yellow-green
Cutibacterium acnes, a bacterium involved in acne causation, exhibits an orange glow under a Wood's lamp.
Ethylene glycol poisoning | Blacklight | Wikipedia | 497 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
A Wood's lamp may be used to rapidly assess whether an individual is suffering from ethylene glycol poisoning as a consequence of antifreeze ingestion. Manufacturers of ethylene glycol-containing antifreezes commonly add fluorescein, which causes the patient's urine to fluoresce under Wood's lamp.
Diagnosis
Wood's lamp is useful in diagnosing conditions such as tuberous sclerosis and erythrasma (caused by Corynebacterium minutissimum, see above). Additionally, detection of porphyria cutanea tarda can sometimes be made when urine turns pink upon illumination with Wood's lamp. Wood's lamps have also been used to differentiate hypopigmentation from depigmentation such as with vitiligo. A vitiligo patient's skin will appear yellow-green or blue under the Wood's lamp. Its use in detecting melanoma has been reported.
Security and authentication
Blacklight is commonly used to authenticate oil paintings, antiques and banknotes. It can also differentiate real currency from counterfeit notes because, in many countries, legal banknotes have fluorescent symbols on them that only show under a blacklight. In addition, the paper used for printing money does not contain any of the brightening agents which cause commercially available papers to fluoresce under blacklight. Both of these features make illegal notes easier to detect and more difficult to successfully counterfeit. The same security features can be applied to identification cards such as passports or driver's licenses.
Other security applications include the use of pens containing a fluorescent ink, generally with a soft tip, that can be used to "invisibly" mark items. If the objects that are so marked are subsequently stolen, a blacklight can be used to search for these security markings. At some amusement parks, nightclubs and at other, day-long (or night-long) events, a fluorescent mark is rubber stamped onto the wrist of a guest who can then exercise the option of leaving and being able to return again without paying another admission fee.
Biology
Fluorescent materials are also very widely used in numerous applications in molecular biology, often as "tags" which bind themselves to a substance of interest (for example, DNA), so allowing their visualization. | Blacklight | Wikipedia | 474 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
Thousands of moth and insect collectors all over the world use various types of blacklights to attract moth and insect specimens for photography and collecting. It is one of the preferred light sources for attracting insects and moths at night. They can illuminate animal excreta, such as urine and vomit, that is not always visible to the naked eye.
Fault detection
Blacklight is used extensively in non-destructive testing. Fluorescing fluids are applied to metal structures and illuminated, allowing easy detection of cracks and other weaknesses.
If a leak is suspected in a refrigerator or an air conditioning system, a UV tracer dye can be injected into the system along with the compressor lubricant oil and refrigerant mixture. The system is then run in order to circulate the dye across the piping and components and then the system is examined with a blacklight lamp. Any evidence of fluorescent dye then pinpoints the leaking part which needs replacement.
Art and decor
Blacklight is used to illuminate pictures painted with fluorescent colors, particularly on black velvet, which intensifies the illusion of self-illumination. The use of such materials, often in the form of tiles viewed in a sensory room under UV light, is common in the United Kingdom for the education of students with profound and multiple learning difficulties. Such fluorescence from certain textile fibers, especially those bearing optical brightener residues, can also be used for recreational effect, as seen, for example, in the opening credits of the James Bond film A View to a Kill. Blacklight puppetry is performed in a blacklight theater.
Mineral identification | Blacklight | Wikipedia | 321 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
Blacklights are a common tool for rock-hunting and identification of minerals by their fluorescence. The most common minerals and rocks that glow under UV light are fluorite, calcite, aragonite, opal, apatite, chalcedony, corundum (ruby and sapphire), scheelite, selenite, smithsonite, sphalerite, sodalite. The first person to observe fluorescence in minerals was George Stokes in 1852. He noted the ability of fluorite to produce a blue glow when illuminated with ultraviolet light and called this phenomenon “fluorescence” after the mineral fluorite. Lamps used to visualise seams of fluorite and other fluorescent minerals are commonly used in mines but they tend to be on an industrial scale. The lamps need to be short wavelength to be useful for this purpose and of scientific grade. UVP range of hand held UV lamps are ideal for this purpose and are used by Geologists to identify the best sources of fluorite in mines or potential new mines. Some transparent selenite crystals exhibit an “hourglass” pattern under UV light that is not visible in natural light. These crystals are also phosphorescent. Limestone, marble, and travertine can glow because of calcite presence. Granite, syenite, and granitic pegmatite rocks can also glow.
Curing resins | Blacklight | Wikipedia | 284 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
UV light can be used to harden particular glues, resins and inks by causing a photochemical reaction inside those substances. This process of hardening is called ‘curing’. UV curing is adaptable to printing, coating, decorating, stereolithography, and in the assembly of a variety of products and materials. In comparison to other technologies, curing with UV energy may be considered a low-temperature process, a high-speed process, and is a solventless process, as cure occurs via direct polymerization rather than by evaporation. Originally introduced in the 1960s, this technology has streamlined and increased automation in many industries in the manufacturing sector. A primary advantage of curing with ultraviolet light is the speed at which a material can be processed. Speeding up the curing or drying step in a process can reduce flaws and errors by decreasing time that an ink or coating spends wet. This can increase the quality of a finished item, and potentially allow for greater consistency. Another benefit to decreasing manufacturing time is that less space needs to be devoted to storing items which can not be used until the drying step is finished.
Because UV energy has unique interactions with many different materials, UV curing allows for the creation of products with characteristics not achievable via other means. This has led to UV curing becoming fundamental in many fields of manufacturing and technology, where changes in strength, hardness, durability, chemical resistance, and many other properties are required.
Cockpit lighting, LSD testing and tanning
One of the innovations for night and all-weather flying used by the US, UK, Japan and Germany during World War II was the use of UV interior lighting to illuminate the instrument panel, giving a safer alternative to the radium-painted instrument faces and pointers, and an intensity that could be varied easily and without visible illumination that would give away an aircraft's position. This went so far as to include the printing of charts that were marked in UV-fluorescent inks, and the provision of UV-visible pencils and slide rules such as the E6B.
They may also be used to test for LSD, which fluoresces under blacklight while common substitutes such as 25I-NBOMe do not.
Strong sources of long-wave ultraviolet light are used in tanning beds. | Blacklight | Wikipedia | 473 | 312943 | https://en.wikipedia.org/wiki/Blacklight | Physical sciences | Basics | Physics |
A drug overdose (overdose or OD) is the ingestion or application of a drug or other substance in quantities much greater than are recommended. Typically the term is applied for cases when a risk to health is a potential result. An overdose may result in a toxic state or death.
Classification
The word "overdose" implies that there is a common safe dosage and usage for the drug; therefore, the term is commonly applied only to drugs, not poisons, even though many poisons as well are harmless at a low enough dosage. Drug overdose is sometimes used as a means to commit suicide, as the result of intentional or unintentional misuse of medication. Intentional misuse leading to overdose can include using prescribed or non-prescribed drugs in excessive quantities in an attempt to produce euphoria.
Usage of illicit drugs, in large quantities, or after a period of drug abstinence can also induce overdose. Cocaine and opioid users who inject intravenously can easily overdose accidentally, as the margin between a pleasurable drug sensation and an overdose is small. Unintentional misuse can include errors in dosage caused by failure to read or understand product labels. Accidental overdoses may also be the result of over-prescription, failure to recognize a drug's active ingredient or unwitting ingestion by children. A common unintentional overdose in young children involves multivitamins containing iron.
The term 'overdose' is often misused as a descriptor for adverse drug reactions or negative drug interactions due to mixing multiple drugs simultaneously.
Signs and symptoms
Signs and symptoms of an overdose vary depending on the drug or exposure to toxins. The symptoms can often be divided into differing toxidromes. This can help one determine what class of drug or toxin is causing the difficulties.
Symptoms of opioid overdoses include slow breathing, heart rate and pulse. Opioid overdoses can also cause pinpoint pupils, and blue lips and nails due to low levels of oxygen in the blood. A person experiencing an opioid overdose might also have muscle spasms, seizures and decreased consciousness. A person experiencing an opiate overdose usually will not wake up, even if their name is called or they are shaken vigorously.
Causes
The drugs or toxins that are most frequently involved in overdose and death (grouped by ICD-10): | Drug overdose | Wikipedia | 480 | 313009 | https://en.wikipedia.org/wiki/Drug%20overdose | Biology and health sciences | Types | Health |
Acute alcohol intoxication (F10)
Ethyl alcohol (alcohol)
Methanol poisoning
Ethylene glycol poisoning
Opioid overdose (F11)
Among sedative-hypnotics (F13)
Barbiturate overdose (T42.3)
Benzodiazepine overdose (T42.4)
Uncategorized sedative-hypnotics (T42.6)
Ethchlorvynol (Placidyl)
GHB
Glutethimide (Doriden)
Methaqualone
Ketamine (T41.2)
Among stimulants (F14-F15)
Cocaine overdose (T40.5)
Amphetamine overdose (T43.6)
Methamphetamine overdose (T43.6)
Among tobacco (F17)
Nicotine poisoning (T65.2)
Among poly drug use (F19)
Drug "cocktails" (speedballs)
Medications
Aspirin poisoning (T39.0)
Paracetamol poisoning (Alone or mixed with oxycodone)
Paracetamol toxicity (T39.1)
Tricyclic antidepressant overdose (T43.0)
Vitamin poisoning
Pesticide poisoning (T60)
Organophosphate poisoning
DDT
Inhalants
Lithium toxicity
Added flavoring
Masking undesired taste may impair judgement of the potency, which is a factor in overdosing. For example, lean is usually created as a drinkable mixture, the cough syrup is combined with soft drinks, especially fruit-flavored drinks such as Sprite, Mountain Dew or Fanta, and is typically served in a foam cup. A hard candy, usually a Jolly Rancher, may be added to give the mixture a sweeter flavor.
Diagnosis
The substance that has been taken may often be determined by asking the person. However, if they will not, or cannot, due to an altered level of consciousness, provide this information, a search of the home or questioning of friends and family may be helpful.
Examination for toxidromes, drug testing, or laboratory test may be helpful. Other laboratory test such as glucose, urea and electrolytes, paracetamol levels and salicylate levels are typically done. Negative drug-drug interactions have sometimes been misdiagnosed as an acute drug overdose, occasionally leading to the assumption of suicide. | Drug overdose | Wikipedia | 492 | 313009 | https://en.wikipedia.org/wiki/Drug%20overdose | Biology and health sciences | Types | Health |
Prevention
The distribution of naloxone to injection drug users and other opioid drug users decreases the risk of death from overdose. The Centers for Disease Control and Prevention (CDC) estimates that U.S. programs for drug users and their caregivers prescribing take-home doses of naloxone and training on its utilization are estimated to have prevented 10,000 opioid overdose deaths. Healthcare institution-based naloxone prescription programs have also helped reduce rates of opioid overdose in the U.S. state of North Carolina, and have been replicated in the U.S. military. Nevertheless, scale-up of healthcare-based opioid overdose interventions is limited by providers' insufficient knowledge and negative attitudes towards prescribing take-home naloxone to prevent opioid overdose. Programs training police and fire personnel in opioid overdose response using naloxone have also shown promise in the U.S.
Supervised injection sites (also known as overdose prevention centers) have been used to help prevent drug overdoses by offering opioid reversal medications such as naloxone, medical assistance and treatment options. They also provide clean needles to help prevent the spread of diseases like HIV/AIDS and hepatitis.
Management
Stabilization of the person's airway, breathing, and circulation (ABCs) is the initial treatment of an overdose. Ventilation is considered when there is a low respiratory rate or when blood gases show the person to be hypoxic. Monitoring of the patient should continue before and throughout the treatment process, with particular attention to temperature, pulse, respiratory rate, blood pressure, urine output, electrocardiography (ECG) and O2 saturation. Poison control centers and medical toxicologists are available in many areas to provide guidance in overdoses both to physicians and to the general public.
Antidotes
Specific antidotes are available for certain overdoses. For example, naloxone is the antidote for opiates such as heroin or morphine. Similarly, benzodiazepine overdoses may be effectively reversed with flumazenil. As a nonspecific antidote, activated charcoal is frequently recommended if available within one hour of the ingestion and the ingestion is significant. Gastric lavage, syrup of ipecac, and whole bowel irrigation are rarely used.
Epidemiology and statistics
The UN gives a figure of 300,000 deaths per year in the world through drug overdose. | Drug overdose | Wikipedia | 509 | 313009 | https://en.wikipedia.org/wiki/Drug%20overdose | Biology and health sciences | Types | Health |
1,015,060 US residents died from drug overdoses from 1968 to 2019. 22 people out of every 100,000 died from drug overdoses in 2019 in the US. From 1999 to Feb 2019 in the United States, more than 770,000 people have died from drug overdoses.
In the US around 107,500 people died in the 12-month period ending August 31, 2022, at a rate of 294 deaths per day. 70,630 people died from drug overdoses in 2019. The U.S. drug overdose death rate has gone from 2.5 per 100,000 people in 1968 to 21.5 per 100,000 in 2019.
The National Center for Health Statistics reports that 19,250 people died of accidental poisoning in the U.S. in the year 2004 (eight deaths per 100,000 population).
In 2008 testimony before a Senate subcommittee, Leonard J. Paulozzi, a medical epidemiologist at the Centers for Disease Control and Prevention said that in 2005 more than 22,000 American people died due to overdoses, and the number is growing rapidly. Paulozzi also testified that all available evidence suggests unintentional overdose deaths are related to the increasing use of prescription drugs, especially opioid painkillers. However, the vast majority of overdoses are also attributable to alcohol. It is very rare for a victim of an overdose to have consumed just one drug. Most overdoses occur when drugs are ingested in combination with alcohol.
Drug overdose was the leading cause of injury death in 2013. Among people 25 to 64 years old, drug overdose caused more deaths than motor vehicle traffic crashes. There were 43,982 drug overdose deaths in the United States in 2013. Of these, 22,767 (51.8%) were related to prescription drugs.
The 22,767 deaths relating to prescription drug overdose in 2013, 16,235 (71.3%) involved opioid painkillers, and 6,973 (30.6%) involved benzodiazepines. Drug misuse and abuse caused about 2.5 million emergency department (ED) visits in 2011. Of these, more than 1.4 million ED visits were related to prescription drugs. Among those ED visits, 501,207 visits were related to anti-anxiety and insomnia medications, and 420,040 visits were related to opioid analgesics. | Drug overdose | Wikipedia | 496 | 313009 | https://en.wikipedia.org/wiki/Drug%20overdose | Biology and health sciences | Types | Health |
New CDC data in 2024 demonstrates U.S. drug overdose deaths have significantly declined, marking the potential for the first year with fewer than 100,000 fatalities since 2020. The CDC data shows a nearly 17% drop in reported overdose deaths during the 12 months ending in June, totaling 93,087. This is a notable decrease from the 111,615 deaths recorded in the same period ending in June 2023. While the opioid crisis continues to take a heavy toll, fentanyl remains a major driver, contributing to the majority of these fatalities. | Drug overdose | Wikipedia | 114 | 313009 | https://en.wikipedia.org/wiki/Drug%20overdose | Biology and health sciences | Types | Health |
Acanthuridae are a family of ray-finned fish which includes surgeonfishes, tangs, and unicornfishes. The family includes about 86 extant species of marine fish living in tropical seas, usually around coral reefs. Many of the species are brightly colored and popular in aquaria.
Etymology and taxonomic history
The name of the family is derived from the Greek words akantha and oura, which loosely translate to "thorn" and "tail", respectively. This refers to the distinguishing characteristic of the family, the "scalpel" found on the caudal peduncle. In the early 1900s, the family was called Hepatidae.
Subfamilies and genera
Acanthuridae contains the following extant subfamilies and genera:
Subfamily Nasinae Fowler & Bean, 1929
Genus Naso Lacépède, 1801
Subfamily Acanthurinae Bonaparte, 1835
Tribe Acanthurini Bonaparte, 1839
Genus Acanthurus Forsskål 1775
Genus Ctenochaetus Gill, 1884
Tribe Prionurini J. L. B. Smith, 1966
Genus Prionurus Lacépède, 1804
Tribe Zebrasomini Winterbottom, 1993
Genus Paracanthurus Bleeker, 1863
Genus Zebrasoma Swainson, 1839
Evolution and fossil record
There are several extinct genera known from fossils dating from the Eocene to Miocene:
Eocene genera
Proacanthurus
Tylerichthys
Gazolaichthys
Naseus
Tauichthys
Eorandallius
Metacanthurus
Oligocene genera
Glarithurus
Caprovesposus
Arambourgthurus
?Eonaso
Miocene genera
Marosichthys
Morphology
The distinctive characteristic of the family is that they have scalpel-like modified scales, one or more on either side of the peduncle of the tail. The spines are dangerously sharp and may seriously injure anyone who carelessly handles such a fish. The dorsal, anal, and caudal fins are large, extending for most of the length of the body. The mouths are small and have a single row of teeth adapted to grazing on algae. | Acanthuridae | Wikipedia | 429 | 313073 | https://en.wikipedia.org/wiki/Acanthuridae | Biology and health sciences | Acanthomorpha | Animals |
Surgeonfishes sometimes feed as solitary individuals, but they often travel and feed in schools. Feeding in schools may be a mechanism for overwhelming the highly aggressive defense responses of small territorial damselfishes that vigorously guard small patches of algae on coral reefs.
Most species are fairly small, with a maximum length of , but some in the genus Acanthurus, some in the genus Prionurus, and most species in the genus Naso may grow larger; the whitemargin unicornfish (Naso annulatus) is the largest species in the family, reaching a length of up to . These fishes may grow quickly in aquaria, so average growth size and suitability should be checked before adding them to any marine aquarium.
A larval acanthurid, known as an acronurus, looks strikingly different from the juvenile and adult forms of the same individual. It is mostly transparent and tends to have a pelagic lifestyle, living in open water for an extended period of time before settling on the ocean bottom near the shore, where it develops into the juvenile and ultimately the adult form.
Symbiotic bacteria
Acanthurids are the only known hosts of the bacteria of the genus Epulopiscium bacteria. These bacteria affect the digestion of surgeonfishes enabling them to digest the algae in their diet.
In the aquarium
Tangs are very sensitive to disease in the home aquarium. However, if the tang is fed enough algae and the aquarium is properly maintained disease should not be a problem. It is usually necessary to quarantine the animals for a period before introducing them to the aquarium.
Adults range from in length and most grow quickly even in aquaria. When considering a tang for an aquarium it is important to consider the size to which these fish can grow. Larger species such as the popular Pacific blue tang surgeonfish (of Finding Nemo fame), Naso or lipstick tang, lined surgeonfish, Sohal surgeonfish and Atlantic blue tang surgeonfish can grow to and require swimming room and hiding places.
Many also suggest adding aggressive tangs to the aquarium last as they are territorial and may fight and possibly kill other fish. | Acanthuridae | Wikipedia | 436 | 313073 | https://en.wikipedia.org/wiki/Acanthuridae | Biology and health sciences | Acanthomorpha | Animals |
Tangs primarily graze on macroalgae from genera such as Caulerpa and Gracilaria, although they have been observed in an aquarium setting to eat meat-based fish foods. A popular technique for aquarists, is to grow macroalgae in a sump or refugium. This technique not only is economically beneficial, but serves to promote enhanced water quality through nitrate absorption. The growth of the algae can then be controlled by feeding it to the tang.
Gallery | Acanthuridae | Wikipedia | 101 | 313073 | https://en.wikipedia.org/wiki/Acanthuridae | Biology and health sciences | Acanthomorpha | Animals |
Phytolacca is a genus of perennial plants native to North America, South America and East Asia. Some members of the genus are known as pokeweeds or similar names such as pokebush, pokeberry, pokeroot or poke sallet. Other names for species of Phytolacca include inkberry and ombú. The generic name is derived from the Greek word (phyton), meaning "plant," and the Latin word lacca, a red dye. Phytolaccatoxin and phytolaccigenin are present (in the leaves, stems, roots, blossoms, berries etc.) in many species which are poisonous to mammals if not prepared properly. The berries are eaten by birds, which are not affected by the toxin. The small seeds with very hard outer shells remain intact in the digestive system and are eliminated whole.
The genus comprises about 25 to 35 species of perennial herbs, shrubs, and trees growing from tall. They have alternate simple leaves, pointed at the end, with entire or crinkled margins; the leaves can be either deciduous or evergreen. The stems are green, pink or red. The flowers are greenish-white to pink, produced in long racemes at the ends of the stems. They develop into globose berries diameter, green at first, ripening dark purple to black.
Selected species | Phytolacca | Wikipedia | 276 | 313236 | https://en.wikipedia.org/wiki/Phytolacca | Biology and health sciences | Caryophyllales | Plants |
The following species are accepted by one or more regional floras:
Phytolacca acinosa Roxb. – Indian poke. Southern and eastern Asia (syn. P. esculenta Van Houtte, P. latbenia (Moq.) Walter). Black and Judziewicz report it in Dane County, Wisconsin in their 2008 and 2009 books (Wildflowers of Wisconsin and the Great Lakes Region. A Comprehensive Field Guide, first and 2nd editions. )
Phytolacca americana L. – American pokeweed. North America (syn. P. decandra L.)
Phytolacca australis Phil. – Western South America
Phytolacca bogotensis Kunth – Tropical and subtropical South America (sometimes included in P. icosandra).
Phytolacca chilensis Miers – central Chile (possibly synonymous with P. icosandra)
Phytolacca dioica L. – Ombú. Subtropical South America.
Phytolacca dodecandra L'Hér. – Eastern Africa, Madagascar (syn. P. abyssinica Hoffm.).
Phytolacca heterotepala H.Walt. – Mexican pokeweed. Mexico.
Phytolacca icosandra L. – Central and South America.
Phytolacca japonica Makino – Eastern Asia (syn. P. hunanensis Hand.-Mazz., P. zhejiangensis W.T.Fan).
Phytolacca octandra L. – Red inkplant. Subtropical and tropical regions worldwide (sometimes included in P. icosandra).
Phytolacca polyandra Batalin – Central and southwest China (syn. P. clavigera W.W.Smith).
Phytolacca pruinosa Fenzl – Levantine Pokeweed. Southern Turkey, Cyprus, Lebanon and Syria.
Phytolacca rivinoides Kunth & C.D.Bouché – Central and South America.
Phytolacca sandwicensis Endl. – Hawaiian Pokeweed. Hawaii.
Phytolacca thyrsiflora Fenzl ex J.A.Schmidt – Northern South America.
Phytolacca weberbaueri H.Walt. – Yumbi. Peru.
Formerly placed here
Leea asiatica (L.) Ridsdale (as P. asiatica L.)
Terminalia catappa L. (as P. javanica Osbeck)
Ecology | Phytolacca | Wikipedia | 508 | 313236 | https://en.wikipedia.org/wiki/Phytolacca | Biology and health sciences | Caryophyllales | Plants |
The ombú (Phytolacca dioica) grows as a tree on the pampas of South America and is one of the few providers of shade on the open grassland. It is a symbol of Uruguay, Argentina and gaucho culture. P. weberbaueri from Peru also grows to tree size. Both species have massively buttressed bases to their trunks, and very soft wood with a high water storage capacity which makes them resistant to grass fires and drought.
In the Pacific Northwest of North America, pokeweed is an invasive species.
Uses
Phytolacca americana (American pokeweed, pokeweed, poke) is used as a folk medicine and as food, although all parts of it must be considered toxic unless, as folk recipes claim, it is "properly prepared." The root is never eaten and cannot be made edible. Poke salad ('poke salat') is considered part of traditional southern U.S. cuisine, where it is cooked three times in three changes of boiling water to remove some of the harmful components. Toxic constituents which have been identified include the alkaloids phytolaccine and phytolaccotoxin, as well as a glycoprotein.
Fossil record
A Phytolacca-like fossil has been described from the Upper Cretaceous (late Campanian) Cerro del Pueblo Formation, Coahuila, Mexico, it is a permineralized multiple infructescence composed of berries with six locules, each containing a single seed with a curved embryo developed in a curved ovule with pendulous placentation, a berry anatomy that is similar to that of the genus Phytolacca. Though this new plant from Coahuila shares reproductive characters with Phytolacca, the constant number (six) of carpels per fruit and pendulous placentation support the recognition of a new genus, Coahuilacarpon phytolaccoides. | Phytolacca | Wikipedia | 393 | 313236 | https://en.wikipedia.org/wiki/Phytolacca | Biology and health sciences | Caryophyllales | Plants |
Cauterization (or cauterisation, or cautery) is a medical practice or technique of burning a part of a body to remove or close off a part of it. It destroys some tissue in an attempt to mitigate bleeding and damage, remove an undesired growth, or minimize other potential medical harm, such as infections when antibiotics are unavailable.
The practice was once widespread for treatment of wounds. Its utility before the advent of antibiotics was said to be effective at more than one level:
To prevent exsanguination
To close amputations
Cautery was historically believed to prevent infection, but current research shows that cautery actually increases the risk for infection by causing more tissue damage and providing a more hospitable environment for bacterial growth. Actual cautery refers to the metal device, generally heated to a dull red glow, that a physician applies to produce blisters, to stop bleeding of a blood vessel, and for other similar purposes.
The main forms of cauterization used today are electrocautery and chemical cautery—both are, for example, prevalent in cosmetic removal of warts and stopping nosebleeds. Cautery can also mean the branding of a human.
Etymology
Cauterize is a Middle English word borrowed from the Old French , from Late Latin "to burn or brand with a hot iron", from Ancient Greek (), from (), "burning or branding iron", and (kaiein) "to burn" (of caustic).
History
Cauterization has been used to stop heavy bleeding since antiquity. The process was described in the Edwin Smith Papyrus and Hippocratic Corpus. It was primarily used to control hemorrhages, especially those resulting from surgery, in ancient Greece. Archigenes recommended cauterization in the event of hemorrhaging wounds, and Leonides of Alexandria described excising breast tumors and cauterizing the resulting wound in order to control bleeding. The Chinese recommends cauterization as a treatment for various ailments, including dog bites. Indigenous peoples of the Americas, ancient Arabs, and Persians also used the technique.
Tools used in the ancient cauterization process ranged from heated lances to cauterizing knives. The piece of metal was heated over fire and applied to the wound. | Cauterization | Wikipedia | 470 | 313295 | https://en.wikipedia.org/wiki/Cauterization | Biology and health sciences | Treatments | Health |
Cauterization continued to be used as a common treatment in medieval times. The Babylonian Talmud (redacted in 500 AD), alluding to the practice, states: "... and the effect of the hot iron comes and removes the traces of the stroke." While mainly employed to stop blood loss, it was also used in cases of tooth extraction and as a treatment for mental illness. In the Muslim world, scholars Al-Zahrawi and Avicenna wrote about techniques and instruments used for cauterization.
As late as the 20th-century, Bedouins of the Negev in Israel had it as their practice to take the root of the shaggy sparrow-wort (Thymelaea hirsuta), cut the root into splinters lengthwise, burn the splinter in fire, and then apply the red-hot tip of a splinter to the forehead of a person who was ill with ringworm (dermatophytosis).
The technique of ligature of the arteries as an alternative to cauterization was later improved and used more effectively by Ambroise Paré.
Electrocautery
Electrocauterization is the process of destroying tissue (or cutting through soft tissue) using heat conduction from a metal probe heated by electric current. The procedure stops bleeding from small vessels (larger vessels being ligated). Electrocautery applies high frequency alternating current by a unipolar or bipolar method. It can be a continuous waveform to cut tissue, or intermittent to coagulate tissue.
The electrically produced heat in this process inherently can do numerous things to the tissue, depending on the waveform and power level, including cauterize, coagulate, cut, and dry (desiccate). Thus electrocautery, electrocoagulation, electrodesiccation, and electrocurettage are closely related and can co-occur in the same procedure when desired. Electrodesiccation and curettage is a common procedure.
Unipolar
In unipolar cauterization, the physician contacts the tissue with a single small electrode. The circuit's exit point is a large surface area, such as the buttocks, to prevent electrical burns. The amount of heat generated depends on the size of contact area, power setting or frequency of current, duration of application, and waveform. A constant waveform generates more heat than intermittent. The frequency used in cutting the tissue is higher than in coagulation mode. | Cauterization | Wikipedia | 501 | 313295 | https://en.wikipedia.org/wiki/Cauterization | Biology and health sciences | Treatments | Health |
Bipolar
Bipolar electrocautery passes the current between two tips of a forceps-like tool. It has the advantage of not disturbing other electrical body rhythms (such as the heart) and also coagulates tissue by pressure. Lateral thermal injury is greater in unipolar than bipolar devices.
Electrocauterization is preferable to chemical cauterization, because chemicals can leach into neighbouring tissue and cauterize outside of intended boundaries. Concern has also been raised regarding toxicity of the surgical smoke electrocautery produces. This contains chemicals that, through inhalation, may harm patients or medical staff.
Ultrasonic coagulation and ablation systems are also available.
Chemical cautery
Many chemical reactions can destroy tissue, and some are used routinely in medicine, most commonly to remove small skin lesions such as warts or necrotized tissue, or for hemostasis. Because chemicals can leach into areas not intended for cauterization, laser and electrical methods are preferable where practical. Some cauterizing agents are:
Silver nitrate is the active ingredient of the lunar caustic, a stick that traditionally looks like a large match. It is dipped in water and pressed onto the lesion for a few moments.
Trichloroacetic acid
Cantharidin is an extract of the blister beetle that causes epidermal necrosis and blistering. It is used to treat warts.
Nasal cauterization
Frequent nosebleeds are most likely caused by an exposed blood vessel in the nose, usually one in Kiesselbach's plexus.
Even if the nose is not bleeding at the time, a physician may cauterize it to prevent future bleeding. Cauterization methods include burning the affected area with acid, hot metal, or lasers. Such a procedure is naturally quite painful. Sometimes, a physician uses liquid nitrogen as a less painful alternative, though it is less effective. A physician may apply cocaine in the few countries that allow it for medical use. Cocaine is the only local anesthetic that also produces vasoconstriction, making it ideal for controlling nosebleeds.
More modern treatment applies silver nitrate after a local anesthetic. The procedure is generally painless, but after the anesthetic wears off, there may be pain for several days, and the nose may run for up to a week after this treatment.
Nasal cauterization can cause empty nose syndrome. | Cauterization | Wikipedia | 494 | 313295 | https://en.wikipedia.org/wiki/Cauterization | Biology and health sciences | Treatments | Health |
Infant circumcision
Cauterization has been used for the circumcision of infants in the United States and Canada. The College of Physicians and Surgeons of Manitoba advises against its use in neonatal circumcision. This method of circumcision resulted in several infants having their penises severely burned. | Cauterization | Wikipedia | 64 | 313295 | https://en.wikipedia.org/wiki/Cauterization | Biology and health sciences | Treatments | Health |
A rip current (or just rip) is a specific type of water current that can occur near beaches where waves break. A rip is a strong, localized, and narrow current of water that moves directly away from the shore by cutting through the lines of breaking waves, like a river flowing out to sea. The force of the current in a rip is strongest and fastest next to the surface of the water.
Rip currents can be hazardous to people in the water. Swimmers who are caught in a rip current and who do not understand what is happening, or who may not have the necessary water skills, may panic, or they may exhaust themselves by trying to swim directly against the flow of water. Because of these factors, rip currents are the leading cause of rescues by lifeguards at beaches. In the United States they cause an average of 71 deaths by drowning per year .
A rip current is not the same thing as undertow, although some people use that term incorrectly when they are talking about a rip current. Contrary to popular belief, neither rip nor undertow can pull a person down and hold them under the water. A rip simply carries floating objects, including people, out to just beyond the zone of the breaking waves, at which point the current dissipates and releases everything it is carrying.
Causes and occurrence
A rip current forms because wind and breaking waves push surface water towards the land. This causes a slight rise in the water level along the shore. This excess water will tend to flow back to the open water via the route of least resistance. When there is a local area which is slightly deeper, such as a break in an offshore sand bar or reef, this can allow water to flow offshore more easily, and this will initiate a rip current through that gap.
Water that has been pushed up near the beach flows along the shore towards the outgoing rip as "feeder currents". The excess water flows out at a right angle to the beach, in a tight current called the "neck" of the rip. The "neck" is where the flow is most rapid. When the water in the rip current reaches outside of the lines of breaking waves, the flow disperses sideways, loses power, and dissipates in what is known as the "head" of the rip. | Rip current | Wikipedia | 460 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
Rip currents can form by the coasts of oceans, seas, and large lakes, whenever there are waves of sufficient energy. Rip currents often occur on a gradually shelving shore, where breaking waves approach the shore parallel to it, or where underwater topography encourages outflow at one specific area. Baïnes are one of the patterns identified to be producing rip currents. The location of rip currents can be difficult to predict. Some tend to recur always in the same places, but others can appear and disappear suddenly at various locations along the beach. The appearance and disappearance of rip currents is dependent upon the bottom topography and the direction from which the surf and swells are coming.
Rip currents occur wherever there is strong longshore variability in wave breaking. This variability may be caused by such features as sandbars, by piers and jetties, and even by crossing wave trains. They are often located in places where there is a gap in a reef, or low area on a sandbar. Rip currents, once they have formed, may deepen the channel through a sandbar.
Rip currents are usually quite narrow, but they tend to be more common, wider, and faster, when and where breaking waves are large and powerful. Local underwater topography makes some beaches more likely to have rip currents. A few beaches are notorious in this respect.
Although rip tide is a misnomer, in areas of significant tidal range, rip currents may only occur at certain stages of the tide, when the water is shallow enough to cause the waves to break over a sand bar, but deep enough for the broken wave to flow over the bar. In parts of the world with a big difference between high tide and low tide, and where the shoreline shelves gently, the distance between a bar and the shoreline may vary from a few meters to a kilometer or more, depending whether it is high tide or low tide.
A fairly common misconception is that rip currents can pull a swimmer down, under the surface of the water. This is not true, and in reality a rip current is strongest close to the surface, as the flow near the bottom is slowed by friction.
The surface of a rip current can often appear to be a relatively smooth area of water, without any breaking waves, and this deceptive appearance may cause some beach-goers to believe that it is a suitable place to enter the water. | Rip current | Wikipedia | 477 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
Technical description
A more detailed and technical description of rip currents requires understanding the concept of radiation stress. Radiation stress is the force (or momentum flux) that is exerted on the water column by the presence of the wave. When a wave reaches shallow water and shoals, it increases in height prior to breaking. During this increase in height, radiation stress increases, because of the force exerted by the weight of the water that has been pushed upwards.
To balance this, the local mean surface level drops. This is known as the setdown. When the wave breaks and starts reducing in height, the radiation stress decreases as the amount of water that is elevated decreases. When this happens, the mean surface level increases — this is known as the setup.
In the formation of a rip current, a wave propagates over a sandbar with a gap in it. When this happens, most of the wave breaks on the sandbar, leading to "setup". The part of the wave that propagates over the gap does not break, and the "setdown" continues in that part. Because of this phenomenon, the mean water surface over the rest of the sandbar is higher than that which is over the gap. The result is a strong flow outward through the gap. This strong flow is the rip current.
The vorticity and inertia of rip currents have been studied. From a model of the vorticity of a rip current done at Scripps Institute of Oceanography, it was found that as a fast rip current extends away from shallow water, the vorticity of the current increases, and the width of the current decreases. This model acknowledges that friction plays a role and waves are irregular in nature. From data from Sector-Scanning Doppler Sonar at Scripps Institute of Oceanography, it was found that rip currents in La Jolla, California, lasted several minutes, that they reoccurred one to four times per hour, and that they created a wedge with a 45° arch and a radius of 200–400 meters.
Visible characteristics
Rip currents have a characteristic appearance, and, with some experience, they can be visually identified from the shore before entering the water. This is helpful to lifeguards, swimmers, surfers, boaters, divers and other water users, who may need to avoid a rip, or in some cases make use of the flow. | Rip current | Wikipedia | 486 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
Rip currents often look somewhat like a road or river running straight out to sea. They are easiest to notice and identify when the zone of breaking waves is viewed from a high vantage point. The following are some visual characteristics that can be used to identify a rip:
A noticeable break in the pattern of the waves — the water often looks flat at the rip, in contrast to the lines of breaking waves on either side of the rip.
A "river" of foam — the surface of the rip sometimes looks foamy, because the current is carrying foam from the surf out to open water.
Different color — the rip may differ in color from the surrounding water. It is often more opaque, cloudier, or muddier, and so, depending on the angle of the sun, the rip may show as darker or lighter than the surrounding water.
It is sometimes possible to see that foam or floating debris on the surface of the rip is moving out, away from the shore. In contrast, in the surrounding areas of breaking waves, floating objects and foam are being pushed towards the shore.
These characteristics are helpful in learning to recognize and understand the nature of rip currents. Learning these signs can enable a person to recognize the presence and position of rips before entering the water, which is an important skill as studies show the majority of people are unable to identify a rip current and therefore unable to identify safe places to swim.
In the United States, some beaches have signs created by the National Oceanic and Atmospheric Administration (NOAA) and United States Lifesaving Association, explaining what a rip current is and how to escape one. These signs are titled, "Rip Currents; Break the Grip of the Rip". Two of these signs are shown in the image at the top of this article. Beachgoers can get information from lifeguards, who are always watching for rip currents, and who will move their safety flags so that swimmers can avoid rips.
Danger to swimmers
Rip currents are a potential source of danger for people in shallow water with breaking waves, whether this is in seas, oceans or large lakes. Rip currents are the proximate cause of 80% of rescues carried out by beach lifeguards. | Rip current | Wikipedia | 442 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
Rip currents typically flow at about . They can be as fast as , which is faster than any human can swim. Most rip currents are fairly narrow, and even the widest rip currents are not very wide. Swimmers can usually exit the rip easily by swimming at a right angle to the flow, parallel to the beach. Swimmers who are unaware of this fact may exhaust themselves trying unsuccessfully to swim directly against the flow. The flow of the current fades out completely at the head of the rip, outside the zone of the breaking waves, so there is a definite limit to how far the swimmer will be taken out to sea by the flow of a rip current.
In a rip current, death by drowning occurs when a person has limited water skills and panics, or when a swimmer persists in trying to swim to shore against a strong rip current, and eventually becomes exhausted and drowns.
According to the NOAA rip currents caused an average of 71 deaths annually in the United States over the ten years ending in 2022 (with 69 in 2022).
A 2013 Australian study found that rips killed more people in Australia than bushfires, floods, cyclones and shark attacks combined.
Survival
People caught in a rip current may notice that they are moving away from the shore quite rapidly. Often, it is not possible to swim directly back to shore against a rip current, so this is not recommended. Contrary to popular misunderstanding, a rip does not pull a swimmer under the water. It carries the swimmer away from the shore in a narrow band of moving water.
A rip current is like a moving treadmill, which the swimmer can get out of quite easily by swimming at a right angle, across the current, i.e. parallel to the shore in either direction. Rip currents are usually not very wide, so getting out of one only takes a few strokes. Once out of the rip current, getting back to shore is not difficult, since waves are breaking, and floating objects, including swimmers, will be pushed by the waves towards the shore.
As an alternative, people who are caught in a strong rip can simply relax, either floating or treading water, and allow the current to carry them until it dissipates completely once it is beyond the surf line. Then the person can signal for help, or swim back through the surf, doing so diagonally, away from the rip and towards the shore. | Rip current | Wikipedia | 483 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
It is necessary for coastal swimmers to understand the danger of rip currents, to learn how to recognize them, and how to deal with them. And when possible, it is necessary that people enter the water only in areas where lifeguards are on duty.
In a planned trial in a large rip current at Muriwai Beach in New Zealand, an Australian researcher from the School of Biological, Earth and Environmental Sciences, UNSW Sydney found that "just swim to the side" would not work as the rip current was too wide to see its sides, and said that, despite a rescue boat being near, he was unable to relax and not panic. The current took him 300 metres along the beach in a channel feeding the rip current, and then 400 metres offshore at "speeds approaching those of swimming world records".
Uses
Experienced and knowledgeable water users, including surfers, body boarders, divers, surf lifesavers and kayakers, when they wish to get out beyond the breaking waves, will sometimes use a rip current as a rapid and effortless means of transportation. | Rip current | Wikipedia | 217 | 313371 | https://en.wikipedia.org/wiki/Rip%20current | Physical sciences | Oceanography | Earth science |
In arithmetic, long division is a standard division algorithm suitable for dividing multi-digit Hindu-Arabic numerals (positional notation) that is simple enough to perform by hand. It breaks down a division problem into a series of easier steps.
As in all division problems, one number, called the dividend, is divided by another, called the divisor, producing a result called the quotient. It enables computations involving arbitrarily large numbers to be performed by following a series of simple steps. The abbreviated form of long division is called short division, which is almost always used instead of long division when the divisor has only one digit.
History
Related algorithms have existed since the 12th century.
Al-Samawal al-Maghribi (1125–1174) performed calculations with decimal numbers that essentially require long division, leading to infinite decimal results, but without formalizing the algorithm.
Caldrini (1491) is the earliest printed example of long division, known as the Danda method in medieval Italy, and it became more practical with the introduction of decimal notation for fractions by Pitiscus (1608).
The specific algorithm in modern use was introduced by Henry Briggs 1600.
Education
Inexpensive calculators and computers have become the most common way to solve division problems, eliminating a traditional mathematical exercise and decreasing the educational opportunity to show how to do so by paper and pencil techniques. (Internally, those devices use one of a variety of division algorithms, the faster of which rely on approximations and multiplications to achieve the tasks.) In North America, long division has been especially targeted for de-emphasis or even elimination from the school curriculum by reform mathematics, though it has been traditionally introduced in the 4th, 5th or even 6th grades.
Method
In English-speaking countries, long division does not use the division slash or division sign symbols but instead constructs a tableau. The divisor is separated from the dividend by a right parenthesis or vertical bar ; the dividend is separated from the quotient by a vinculum (i.e., an overbar). The combination of these two symbols is sometimes known as a long division symbol or division bracket. It developed in the 18th century from an earlier single-line notation separating the dividend from the quotient by a left parenthesis. | Long division | Wikipedia | 478 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
The process is begun by dividing the left-most digit of the dividend by the divisor. The quotient (rounded down to an integer) becomes the first digit of the result, and the remainder is calculated (this step is notated as a subtraction). This remainder carries forward when the process is repeated on the following digit of the dividend (notated as 'bringing down' the next digit to the remainder). When all digits have been processed and no remainder is left, the process is complete.
An example is shown below, representing the division of 500 by 4 (with a result of 125).
125 (Explanations)
4)500
4 ( 4 × 1 = 4)
10 ( 5 - 4 = 1)
8 ( 4 × 2 = 8)
20 (10 - 8 = 2)
20 ( 4 × 5 = 20)
0 (20 - 20 = 0)
A more detailed breakdown of the steps goes as follows: | Long division | Wikipedia | 195 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
Find the shortest sequence of digits starting from the left end of the dividend, 500, that the divisor 4 goes into at least once. In this case, this is simply the first digit, 5. The largest number that the divisor 4 can be multiplied by without exceeding 5 is 1, so the digit 1 is put above the 5 to start constructing the quotient.
Next, the 1 is multiplied by the divisor 4, to obtain the largest whole number that is a multiple of the divisor 4 without exceeding the 5 (4 in this case). This 4 is then placed under and subtracted from the 5 to get the remainder, 1, which is placed under the 4 under the 5.
Afterwards, the first as-yet unused digit in the dividend, in this case the first digit 0 after the 5, is copied directly underneath itself and next to the remainder 1, to form the number 10.
At this point the process is repeated enough times to reach a stopping point: The largest number by which the divisor 4 can be multiplied without exceeding 10 is 2, so 2 is written above as the second leftmost quotient digit. This 2 is then multiplied by the divisor 4 to get 8, which is the largest multiple of 4 that does not exceed 10; so 8 is written below 10, and the subtraction 10 minus 8 is performed to get the remainder 2, which is placed below the 8.
The next digit of the dividend (the last 0 in 500) is copied directly below itself and next to the remainder 2 to form 20. Then the largest number by which the divisor 4 can be multiplied without exceeding 20, which is 5, is placed above as the third leftmost quotient digit. This 5 is multiplied by the divisor 4 to get 20, which is written below and subtracted from the existing 20 to yield the remainder 0, which is then written below the second 20.
At this point, since there are no more digits to bring down from the dividend and the last subtraction result was 0, we can be assured that the process finished.
If the last remainder when we ran out of dividend digits had been something other than 0, there would have been two possible courses of action: | Long division | Wikipedia | 467 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
We could just stop there and say that the dividend divided by the divisor is the quotient written at the top with the remainder written at the bottom, and write the answer as the quotient followed by a fraction that is the remainder divided by the divisor.
We could extend the dividend by writing it as, say, 500.000... and continue the process (using a decimal point in the quotient directly above the decimal point in the dividend), in order to get a decimal answer, as in the following example.
31.75
4)127.00
12 (12 ÷ 4 = 3)
07 (0 remainder, bring down next figure)
4 (7 ÷ 4 = 1 r 3)
3.0 (bring down 0 and the decimal point)
2.8 (7 × 4 = 28, 30 ÷ 4 = 7 r 2)
20 (an additional zero is brought down)
20 (5 × 4 = 20)
0
In this example, the decimal part of the result is calculated by continuing the process beyond the units digit, "bringing down" zeros as being the decimal part of the dividend.
This example also illustrates that, at the beginning of the process, a step that produces a zero can be omitted. Since the first digit 1 is less than the divisor 4, the first step is instead performed on the first two digits 12. Similarly, if the divisor were 13, one would perform the first step on 127 rather than 12 or 1.
Basic procedure for long division of
Find the location of all decimal points in the dividend and divisor .
If necessary, simplify the long division problem by moving the decimals of the divisor and dividend by the same number of decimal places, to the right (or to the left), so that the decimal of the divisor is to the right of the last digit.
When doing long division, keep the numbers lined up straight from top to bottom under the tableau.
After each step, be sure the remainder for that step is less than the divisor. If it is not, there are three possible problems: the multiplication is wrong, the subtraction is wrong, or a greater quotient is needed.
In the end, the remainder, , is added to the growing quotient as a fraction, . | Long division | Wikipedia | 483 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
Invariant property and correctness
The basic presentation of the steps of the process (above)
focus on the what steps are to be performed,
rather than the properties of those steps that ensure the result will be correct
(specifically, that q × m + r = n, where q is the final quotient and r the final remainder).
A slight variation of presentation requires more writing,
and requires that we change, rather than just update, digits of the quotient,
but can shed more light on why these steps actually produce the right answer
by allowing evaluation of q × m + r at intermediate points in the process.
This illustrates the key property used in the derivation of the algorithm
(below).
Specifically, we amend the above basic procedure so that
we fill the space after the digits of the quotient under construction with 0's, to at least the 1's place,
and include those 0's in the numbers we write below the division bracket.
This lets us maintain an invariant relation at every step:
q × m + r = n, where q is the partially-constructed quotient (above the division bracket)
and r the partially-constructed remainder (bottom number below the division bracket).
Note that, initially q=0 and r=n, so this property holds initially;
the process reduces r and increases q with each step,
eventually stopping when r<m if we seek the answer in quotient + integer remainder form.
Revisiting the 500 ÷ 4 example above, we find
125 (q, changes from 000 to 100 to 120 to 125 as per notes below)
4)500
400 ( 4 × 100 = 400)
100 (500 - 400 = 100; now q=100, r=100; note q×4+r = 500.)
80 ( 4 × 20 = 80)
20 (100 - 80 = 20; now q=120, r= 20; note q×4+r = 500.)
20 ( 4 × 5 = 20)
0 ( 20 - 20 = 0; now q=125, r= 0; note q×4+r = 500.)
Example with multi-digit divisor
A divisor of any number of digits can be used. In this example, 1260257 is to be divided by 37. First the problem is set up as follows:
37)1260257 | Long division | Wikipedia | 484 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
Digits of the number 1260257 are taken until a number greater than or equal to 37 occurs. So 1 and 12 are less than 37, but 126 is greater. Next, the greatest multiple of 37 less than or equal to 126 is computed. So 3 × 37 = 111 < 126, but 4 × 37 > 126. The multiple 111 is written underneath the 126 and the 3 is written on the top where the solution will appear:
3
37)1260257
111
Note carefully which place-value column these digits are written into. The 3 in the quotient goes in the same column (ten-thousands place) as the 6 in the dividend 1260257, which is the same column as the last digit of 111.
The 111 is then subtracted from the line above, ignoring all digits to the right:
3
37)1260257
111
15
Now the digit from the next smaller place value of the dividend is copied down and appended to the result 15:
3
37)1260257
111
150
The process repeats: the greatest multiple of 37 less than or equal to 150 is subtracted. This is 148 = 4 × 37, so a 4 is added to the top as the next quotient digit. Then the result of the subtraction is extended by another digit taken from the dividend:
34
37)1260257
111
150
148
22
The greatest multiple of 37 less than or equal to 22 is 0 × 37 = 0. Subtracting 0 from 22 gives 22, we often don't write the subtraction step. Instead, we simply take another digit from the dividend:
340
37)1260257
111
150
148
225
The process is repeated until 37 divides the last line exactly:
34061
37)1260257
111
150
148
225
222
37
Mixed mode long division
For non-decimal currencies (such as the British £sd system before 1971) and measures (such as avoirdupois) mixed mode division must be used. Consider dividing 50 miles 600 yards into 37 pieces:
mi - yd - ft - in
1 - 634 1 9 r. 15"
37) 50 - 600 - 0 - 0
37 22880 66 348
13 23480 66 348
1760 222 37 333
22880 128 29 15
===== 111 348 ==
170 ===
148
22
66
== | Long division | Wikipedia | 490 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
Each of the four columns is worked in turn. Starting with the miles: 50/37 = 1 remainder 13. No further division is
possible, so perform a long multiplication by 1,760 to convert miles to yards, the result is 22,880 yards. Carry this to the top of the yards column and add it to the 600 yards in the dividend giving 23,480. Long division of 23,480 / 37 now proceeds as normal yielding 634 with remainder 22. The remainder is multiplied by 3 to get feet and carried up to the feet column. Long division of the feet gives 1 remainder 29 which is then multiplied by twelve to get 348 inches. Long division continues with the final remainder of 15 inches being shown on the result line.
Interpretation of decimal results
When the quotient is not an integer and the division process is extended beyond the decimal point, one of two things can happen:
The process can terminate, which means that a remainder of 0 is reached; or
A remainder could be reached that is identical to a previous remainder that occurred after the decimal points were written. In the latter case, continuing the process would be pointless, because from that point onward the same sequence of digits would appear in the quotient over and over. So a bar is drawn over the repeating sequence to indicate that it repeats forever (i.e., every rational number is either a terminating or repeating decimal).
Notation in non-English-speaking countries
China, Japan, Korea use the same notation as English-speaking nations including India. Elsewhere, the same general principles are used, but the figures are often arranged differently.
Latin America
In Latin America (except Argentina, Bolivia, Mexico, Colombia, Paraguay, Venezuela, Uruguay and Brazil), the calculation is almost exactly the same, but is written down differently as shown below with the same two examples used above. Usually the quotient is written under a bar drawn under the divisor. A long vertical line is sometimes drawn to the right of the calculations.
500 ÷ 4 = 125 (Explanations)
4 ( 4 × 1 = 4)
10 ( 5 - 4 = 1)
8 ( 4 × 2 = 8)
20 (10 - 8 = 2)
20 ( 4 × 5 = 20)
0 (20 - 20 = 0)
and | Long division | Wikipedia | 463 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
127 ÷ 4 = 31.75
124
30 (bring down 0; decimal to quotient)
28 (7 × 4 = 28)
20 (an additional zero is added)
20 (5 × 4 = 20)
0
In Mexico, the English-speaking world notation is used, except that only the result of the subtraction is annotated and the calculation is done mentally, as shown below:
125 (Explanations)
4)500
10 ( 5 - 4 = 1)
20 (10 - 8 = 2)
0 (20 - 20 = 0)
In Bolivia, Brazil, Paraguay, Venezuela, French-speaking Canada, Colombia, and Peru, the European notation (see below) is used, except that the quotient is not separated by a vertical line, as shown below:
127|4
−124 31,75
30
−28
20
−20
0
Same procedure applies in Mexico, Uruguay and Argentina, only the result of the subtraction is annotated and the calculation is done mentally.
Eurasia
In Spain, Italy, France, Portugal, Lithuania, Romania, Turkey, Greece, Belgium, Belarus, Ukraine, and Russia, the divisor is to the right of the dividend, and separated by a vertical bar. The division also occurs in the column, but the quotient (result) is written below the divider, and separated by the horizontal line. The same method is used in Iran, Vietnam, and Mongolia.
127|4
−124|31,75
30
−28
20
−20
0
In Cyprus, as well as in France, a long vertical bar separates the dividend and subsequent subtractions from the quotient and divisor, as in the example below of 6359 divided by 17, which is 374 with a remainder of 1.
6359|17
−51 |374
125 |
−119 |
69|
−68|
1|
Decimal numbers are not divided directly, the dividend and divisor are multiplied by a power of ten so that the division involves two whole numbers. Therefore, if one were dividing 12,7 by 0,4 (commas being used instead of decimal points), the dividend and divisor would first be changed to 127 and 4, and then the division would proceed as above. | Long division | Wikipedia | 469 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
In Austria, Germany and Switzerland, the notational form of a normal equation is used. <dividend> : <divisor> = <quotient>, with the colon ":" denoting a binary infix symbol for the division operator (analogous to "/" or "÷"). In these regions the decimal separator is written as a comma. (cf. first section of Latin American countries above, where it's done virtually the same way):
127 : 4 = 31,75
−12
07
−4
30
−28
20
−20
0
The same notation is adopted in Denmark, Norway, Bulgaria, North Macedonia, Poland, Croatia, Slovenia, Hungary, Czech Republic, Slovakia, Vietnam and in Serbia.
In the Netherlands, the following notation is used:
12 / 135 \ 11,25
12
15
12
30
24
60
60
0
In Finland, the Italian method detailed above was replaced by the Anglo-American one in the 1970s. In the early 2000s, however, some textbooks have adopted the German method as it retains the order between the divisor and the dividend.
Algorithm for arbitrary base
Every natural number can be uniquely represented in an arbitrary number base as a sequence of digits where for all , where is the number of digits in . The value of in terms of its digits and the base is
Let be the dividend and be the divisor, where is the number of digits in . If , then quotient and remainder . Otherwise, we iterate from , before stopping.
For each iteration , let be the quotient extracted so far, be the intermediate dividend, be the intermediate remainder, be the next digit of the original dividend, and be the next digit of the quotient. By definition of digits in base , . By definition of remainder, . All values are natural numbers. We initiate
the first digits of .
With every iteration, the three equations are true:
There only exists one such such that .
The final quotient is and the final remainder is
Examples
In base 10, using the example above with and , the initial values and .
Thus, and .
In base 16, with and , the initial values are and .
Thus, and .
If one doesn't have the addition, subtraction, or multiplication tables for base memorised, then this algorithm still works if the numbers are converted to decimal and at the end are converted back to base . For example, with the above example,
and | Long division | Wikipedia | 505 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
with . The initial values are and .
Thus, and .
This algorithm can be done using the same kind of pencil-and-paper notations as shown in above sections.
d8f45 r. 5
12 ) f412df
ea
a1
90
112
10e
4d
48
5f
5a
5
Rational quotients
If the quotient is not constrained to be an integer, then the algorithm does not terminate for . Instead, if then by definition. If the remainder is equal to zero at any iteration, then the quotient is a -adic fraction, and is represented as a finite decimal expansion in base positional notation. Otherwise, it is still a rational number but not a -adic rational, and is instead represented as an infinite repeating decimal expansion in base positional notation.
Binary division
Performance
On each iteration, the most time-consuming task is to select . We know that there are possible values, so we can find using comparisons. Each comparison will require evaluating . Let be the number of digits in the dividend and be the number of digits in the divisor . The number of digits in . The multiplication of is therefore , and likewise the subtraction of . Thus it takes to select . The remainder of the algorithm are addition and the digit-shifting of and to the left one digit, and so takes time and in base , so each iteration takes , or just . For all digits, the algorithm takes time , or in base .
Generalizations
Rational numbers
Long division of integers can easily be extended to include non-integer dividends, as long as they are rational. This is because every rational number has a recurring decimal expansion. The procedure can also be extended to include divisors which have a finite or terminating decimal expansion (i.e. decimal fractions). In this case the procedure involves multiplying the divisor and dividend by the appropriate power of ten so that the new divisor is an integer – taking advantage of the fact that a ÷ b = (ca) ÷ (cb) – and then proceeding as above.
Polynomials
A generalised version of this method called polynomial long division is also used for dividing polynomials (sometimes using a shorthand version called synthetic division). | Long division | Wikipedia | 453 | 313384 | https://en.wikipedia.org/wiki/Long%20division | Mathematics | Basics | null |
Wingtip devices are intended to improve the efficiency of fixed-wing aircraft by reducing drag. Although there are several types of wing tip devices which function in different manners, their intended effect is always to reduce an aircraft's drag. Wingtip devices can also improve aircraft handling characteristics and enhance safety for following aircraft. Such devices increase the effective aspect ratio of a wing without greatly increasing the wingspan. Extending the span would lower lift-induced drag, but would increase parasitic drag and would require boosting the strength and weight of the wing. At some point, there is no net benefit from further increased span. There may also be operational considerations that limit the allowable wingspan (e.g., available width at airport gates).
Wingtip devices help prevent the flow around the wingtip of higher pressure air under the wing flowing to the lower pressure surface on top at the wingtip, which results in a vortex caused by the forward motion of the aircraft. Winglets also reduce the lift-induced drag caused by wingtip vortices and improve lift-to-drag ratio. This increases fuel efficiency in powered aircraft and increases cross-country speed in gliders, in both cases increasing range. U.S. Air Force studies indicate that a given improvement in fuel efficiency correlates directly with the causal increase in the aircraft's lift-to-drag ratio.
Early history
Wing end-plates
The initial concept dates back to 1897, when English engineer Frederick W. Lanchester patented wing end-plates as a method for controlling wingtip vortices. In the United States, Scottish-born engineer William E. Somerville patented the first functional winglets in 1910. Somerville installed the devices on his early biplane and monoplane designs. Vincent Burnelli received US Patent no: 1,774,474 for his "Airfoil Control Means" on August 26, 1930.
Simple flat end-plates did not cause a reduction in drag, because the increase in profile drag was greater than the decrease in induced drag.
Hoerner wing tips
Following the end of World War II, Dr. Sighard F. Hoerner was a pioneer researcher in the field, having written a technical paper published in 1952 that called for drooped wingtips whose pointed rear tips focused the resulting wingtip vortex away from the upper wing surface. Drooped wingtips are often called "Hoerner tips" in his honor. Gliders and light aircraft have made use of Hoerner tips for many years. | Wingtip device | Wikipedia | 501 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
The earliest-known implementation of a Hoerner-style downward-angled "wingtip device" on a jet aircraft was during World War II. This was the so-called "Lippisch-Ohren" (Lippisch-ears), allegedly attributed to the Messerschmitt Me 163's designer Alexander Lippisch, and first added to the M3 and M4 third and fourth prototypes of the Heinkel He 162A Spatz jet light fighter for evaluation. This addition was done in order to counteract the dutch roll characteristic present in the original He 162 design, related to its wings having a marked dihedral angle. This became a standard feature of the approximately 320 completed He 162A jet fighters built, with hundreds more He 162A airframes going unfinished by V-E Day.
Winglet
The term "winglet" was previously used to describe an additional lifting surface on an aircraft, like a short section between wheels on fixed undercarriage. Richard Whitcomb's research in the 1970s at NASA first used winglet with its modern meaning referring to near-vertical extension of the wing tips. The upward angle (or cant) of the winglet, its inward or outward angle (or toe), as well as its size and shape are critical for correct performance and are unique in each application. The wingtip vortex, which rotates around from below the wing, strikes the cambered surface of the winglet, generating a force that angles inward and slightly forward, analogous to a sailboat sailing close hauled. The winglet converts some of the otherwise-wasted energy in the wingtip vortex to an apparent thrust. This small contribution can be worthwhile over the aircraft's lifetime, provided the benefit offsets the cost of installing and maintaining the winglets.
Another potential benefit of winglets is that they reduce the intensity of wake vortices. Those trail behind the plane and pose a hazard to other aircraft. Minimum spacing requirements between aircraft operations at airports are largely dictated by these factors. Aircraft are classified by weight (e.g. "Light", "Heavy", etc.) because the vortex strength grows with the aircraft lift coefficient, and thus, the associated turbulence is greatest at low speed and high weight, which produced a high angle of attack. | Wingtip device | Wikipedia | 466 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Winglets and wingtip fences also increase efficiency by reducing vortex interference with laminar airflow near the tips of the wing, by 'moving' the confluence of low-pressure (over wing) and high-pressure (under wing) air away from the surface of the wing. Wingtip vortices create turbulence, originating at the leading edge of the wingtip and propagating backwards and inboard. This turbulence 'delaminates' the airflow over a small triangular section of the outboard wing, which destroys lift in that area. The fence/winglet drives the area where the vortex forms upward away from the wing surface, since the center of the resulting vortex is now at the tip of the winglet.
The fuel economy improvement from winglets increases with the mission length. Blended winglets allow a steeper angle of attack reducing takeoff distance.
Early development
Richard T. Whitcomb, an engineer at NASA's Langley Research Center, further developed Hoerner's concept in response to the sharp increase in the cost of fuel after the 1973 oil crisis. With careful aeronautical design he showed that, for a given bending moment, a near-vertical winglet offers a greater drag reduction compared to a horizontal span extension. Whitcomb's designs were flight-tested in 1979–80 by a joint NASA/Air Force team, using a KC-135 Stratotanker based at the Dryden Flight Research Center. A Lockheed L-1011 and McDonnell Douglas DC-10 were also used for testing, and the latter design was directly implemented by McDonnell Douglas on the derivative MD-11, which was rolled out in 1990.
In May 1983, a high school student at Bowie High School in Maryland won a grand prize at the 34th International Science and Engineering Fair in Albuquerque, New Mexico for the result of his research on wingtip devices to reduce drag. The same month, he filed a U.S. patent for "wingtip airfoils", published in 1986.
Applications
NASA
NASA's most notable application of wingtip devices is on the Boeing 747 Shuttle Carrier Aircraft. Located on the 747's horizontal stabilizers, the devices increase the tailplane's effectiveness under the weight of the Space Shuttle orbiter, though these were more for directional stability than for drag reduction.
Business aircraft | Wingtip device | Wikipedia | 468 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Learjet exhibited the prototype Learjet 28 at the 1977 National Business Aviation Association convention. It employed the first winglets ever used on a production aircraft, either civilian or military. Learjet developed the winglet design without NASA assistance. Although the Model 28 was intended to be a prototype experimental aircraft, performance was such that it resulted in a production commitment from Learjet. Flight tests showed that the winglets increased range by about 6.5 percent and improved directional stability. Learjet's application of winglets to production aircraft continued with newer models including the Learjet 55, 31, 60, 45, and Learjet 40.
Gulfstream Aerospace explored winglets in the late 1970s and incorporated winglets in the Gulfstream III, Gulfstream IV and Gulfstream V. The Gulfstream V range of allows nonstop routes such as New York–Tokyo, it holds over 70 world and national flight records.
The Rutan combined winglets-vertical stabilizer appeared on his Beechcraft Starship business aircraft design that first flew in 1986.
Winglets are also applied to other business aircraft, reducing take-off distance to operate from smaller airports, and allowing higher cruise altitudes. Along winglets on new designs, aftermarket vendors developed retrofits. Winglet Technology, LLC of Wichita, Kansas should have tested its elliptical winglets designed to increase payload-range on hot and high departures to retrofit the Citation X.
Experimental
Conventional winglets were fitted to Rutan's Rutan Voyager, the first aircraft to circumnavigate the world without refueling in 1986. The aircraft's wingtips were damaged, however, when they dragged along the runway during takeoff, removing about from each wingtip, so the flight was made without benefit of winglets.
Airliner fuel efficiency
The average commercial jet sees a 4-6 percent increase in fuel efficiency and as much as a 6% decrease in in-flight noise from the use of winglets. Actual fuel savings and the related carbon output can vary significantly by plane, route and flight conditions. | Wingtip device | Wikipedia | 411 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Wingtip fence
A wingtip fence refers to the winglets including surfaces extending both above and below the wingtip, as described in Whitcomb's early research. Both surfaces are shorter than or equivalent to a winglet possessing similar aerodynamic benefits. The Airbus A310-300 was the first airliner with wingtip fences in 1985. Other Airbus models followed with the A300-600, the A320ceo, and the A380. Other Airbus models including the Airbus A320 Enhanced, A320neo, A350 and A330neo have blended winglets rather than wingtip fences. The Antonov An-158 uses wingtip fences.
Canted winglets
Boeing announced a new version of the 747, the 747-400, in 1985, with an extended range and capacity, using a combination of winglets and increased span to carry the additional load. The winglets increased the 747-400's range by 3.5% over the 747-300, which is otherwise aerodynamically identical but has no winglets. The 747-400D variant lacks the wingtip extensions and winglets included on other 747-400s since winglets would provide minimal benefits on short-haul routes while adding extra weight and cost, although the -400D may be converted to the long-range version if needed. Winglets are preferred for Boeing derivative designs based on existing platforms, because they allow maximum re-use of existing components. Newer designs are favoring increased span, other wingtip devices or a combination of both, whenever possible.
The Ilyushin Il-96 was the first Russian and modern jet to feature winglets in 1988. The Bombardier CRJ-100/200 was the first regional airliner to feature winglets in 1992. The A340/A330 followed with canted winglets in 1993/1994. The Tupolev Tu-204 was the first narrowbody aircraft to feature winglets in 1994. The Airbus A220 (née CSeries), from 2016, has canted winglets.
Blended winglets
A blended winglet is attached to the wing with a smooth curve instead of a sharp angle and is intended to reduce interference drag at the wing/winglet junction. A sharp interior angle in this region can interact with the boundary layer flow causing a drag inducing vortex, negating some of the benefit of the winglet. Seattle-based Aviation Partners develops blended winglets as retrofits for the Gulfstream II, Hawker 800 and the Falcon 2000. | Wingtip device | Wikipedia | 511 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
On February 18, 2000, blended winglets were announced as an option for the Boeing 737-800; the first shipset was installed on 14 February 2001 and entered revenue service with Hapag-Lloyd Flug on 8 May 2001. The Aviation Partners/Boeing extensions decrease fuel consumption by 4% for long-range flights and increase range by for the 737-800 or the derivative Boeing Business Jet as standard. Also offered for the 737 Classic, many operators have retrofitted their fleets with these for the fuel savings. Aviation Partners Boeing also offers blended winglets for the 757 and 767-300ER. In 2006 Airbus tested two candidate blended winglets, designed by Winglet Technology and Airbus for the Airbus A320 family. In 2009 Airbus launched its "Sharklet" blended winglet, designed to enhance the payload-range of its A320 family and reduce fuel burn by up to 4% over longer sectors. This corresponds to an annual CO2 reduction of 700 tonnes per aircraft. The A320s fitted with Sharklets were delivered beginning in 2012. They are used on the A320neo, the A330neo and the A350. They are also offered as a retrofit option.
Raked wingtip
Raked wingtips, where the tip has a greater wing sweep than the rest of the wing, are featured on some Boeing Commercial Airplanes to improve fuel efficiency, takeoff and climb performance. Like winglets, they increase the effective wing aspect ratio and diminish wingtip vortices, decreasing lift-induced drag. In testing by Boeing and NASA, they reduce drag by as much as 5.5%, compared to 3.5% to 4.5% for conventional winglets. While an increase in span would be more effective than a same-length winglet, its bending moment is greater. A winglet gives the performance gain of a span increase but has the bending force of a span increase. | Wingtip device | Wikipedia | 394 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Raked wingtips offer several weight-reduction advantages relative to simply extending the conventional main wingspan. At high load-factor structural design conditions, the smaller chords of the wingtip are subjected to less load, and they result in less induced loading on the outboard main wing. Additionally, the leading-edge sweep results in the center of pressure being located farther aft than for simple extensions of the span of conventional main wings. At high load factors, this relative aft location of the center of pressure causes the raked wingtip to be twisted more leading-edge down, reducing the bending moment on the inboard wing. However, the relative aft-movement of the center of pressure accentuates flutter.
Raked wingtips are installed on the Boeing 767-400ER (first flight on October 9, 1999), all generations of Boeing 777 (June 12, 1994) including the upcoming 777X, the 737-derived Boeing P-8 Poseidon (25 April 2009), all variants of the Boeing 787 (December 15, 2009) (the cancelled Boeing 787-3 would have had a wingspan to fit in ICAO Aerodrome Reference Code D, as its wingspan was decreased by using blended winglets instead of raked wingtips ), and the Boeing 747-8 (February 8, 2010). The Embraer E-jet E2 and C-390 Millennium wings also have raked wingtips.
Split-tip
The McDonnell Douglas MD-11 was the first aircraft with split-tip winglets in 1990.
For the 737 Next Generation, third-party vendor Aviation Partners has introduced a similar design to the 737 MAX wingtip device known as the split scimitar winglet, with United Airlines as the launch customer.
The Boeing 737 MAX uses a new type of wingtip device. Resembling a three-way hybrid of a winglet, wingtip fence, and raked wingtip, Boeing claims that this new design should deliver an additional 1.5% improvement in fuel economy over the 10-12% improvement already expected from the 737 MAX.
Gliders | Wingtip device | Wikipedia | 417 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
In 1987, mechanical engineer Peter Masak called on aerodynamicist Mark D. Maughmer, an associate professor of aerospace engineering at the Pennsylvania State University, about designing winglets to improve performance on his wingspan racing sailplane. Others had attempted to apply Whitcomb's winglets to gliders before, and they did improve climb performance, but this did not offset the parasitic drag penalty in high-speed cruise. Masak was convinced it was possible to overcome this hurdle. By trial and error, they ultimately developed successful winglet designs for gliding competitions, using a new PSU–90–125 airfoil, designed by Maughmer specifically for the winglet application. At the 1991 World Gliding Championships in Uvalde, Texas, the trophy for the highest speed went to a winglet-equipped 15-meter class limited wingspan glider, exceeding the highest speed in the unlimited span Open Class, an exceptional result. Masak went on to win the 1993 U.S. 15 Meter Nationals gliding competition, using winglets on his prototype Masak Scimitar.
The Masak winglets were originally retrofitted to production sailplanes, but within 10 years of their introduction, most high-performance gliders were equipped from the factory with winglets or other wingtip devices. It took over a decade for winglets to first appear on a production airliner, the original application that was the focus of the NASA development. Yet, once the advantages of winglets were proven in competition, adoption was swift with gliders. The point difference between the winner and the runner-up in soaring competition is often less than one percent, so even a small improvement in efficiency is a significant competitive advantage. Many non-competition pilots fitted winglets for handling benefits such as increased roll rate and roll authority and reduced tendency for wing tip stall. The benefits are notable, because sailplane winglets must be removable to allow the glider to be stored in a trailer, so they are usually installed only at the pilot's preference.
The Glaser-Dirks DG-303, an early glider derivative design, incorporating winglets as factory standard equipment.
Non-planar wingtip
Aviation Partners developed and flight tested a closed-surface Spiroid winglet on a Falcon 50 in 2010. | Wingtip device | Wikipedia | 460 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Non-planar wingtips are normally angled upwards in a polyhedral wing configuration, increasing the local dihedral near the wing tip, with polyhedral wing designs themselves having been popular on free-flight model aircraft designs for decades. Non-planar wingtips provide the wake control benefit of winglets, with less parasitic drag penalty, if designed carefully. The non-planar wing tip is often swept back like a raked wingtip and may also be combined with a winglet. A winglet is also a special case of a non-planar wingtip.
Aircraft designers employed mostly planar wing designs with simple dihedral after World War II, prior to the introduction of winglets. With the wide acceptance of winglets in new sailplane designs of the 1990s, designers sought to further optimize the aerodynamic performance of their wingtip designs. Glider winglets were originally retrofitted directly to planar wings, with only a small, nearly right-angle, transition area. Once the performance of the winglet itself was optimized, attention was turned to the transition between the wing and winglet. A common application was tapering the transition area from the wing tip chord to the winglet chord and raking the transition area back, to place the winglet in the optimal position. If the tapered portion was canted upward, the winglet height could also be reduced. Eventually, designers employed multiple non-planar sections, each canting up at a greater angle, dispensing with the winglets entirely.
The Schempp-Hirth Discus-2 and Schempp-Hirth Duo Discus use non-planar wingtips.
Active wingtip device | Wingtip device | Wikipedia | 344 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Tamarack Aerospace Group, a company founded in 2010 by aerospace structural engineer Nicholas Guida, has patented an Active Technology Load Alleviation System (ATLAS), a modified version of a wingtip device. The system uses Tamarack Active Camber Surfaces (TACS) to aerodynamically "switch off" the effects of the wingtip device when the aircraft is experiencing high-g events such as large gusts or severe pull-ups. TACS are movable panels, similar to flaps or ailerons, on the trailing edge of the wing extension. The system is controlled by the aircraft's electrical system and a high-speed servo which is activated when the aircraft senses an oncoming stress event, essentially simulating an actuating wingtip. However, the wingtip itself is fixed and the TACS are the only moving part of the wingtip system. Tamarack first introduced ATLAS for the Cessna Citation family aircraft, and it has been certified for use by the Federal Aviation Administration and European Union Aviation Safety Agency.
In December 2024, Tamarack Aerospace had installed 200 Active Winglet on CitationJet airplanes.
Actuating wingtip device
There has been research into actuating wingtip devices, including a filed patent application, though no aircraft currently uses this feature as described. The XB-70 Valkyrie's wingtips were capable of drooping downward in flight, to facilitate Mach 3 flight using waveriding.
Use on rotating blades
Wingtip devices are also used on rotating propeller, helicopter rotor, and wind turbine blades to reduce drag, reduce diameter, reduce noise and/or improve efficiency. By reducing aircraft blade tip vortices interacting with the ground surface during taxiing, takeoff, and hover, these devices can reduce damage from dirt and small stones picked up in the vortices.
Rotorcraft applications
The main rotor blades of the AgustaWestland AW101 (formerly the EH101) have a distinctive tip shape; pilots have found that this rotor design alters the downwash field and reduces brownout which limits visibility in dusty areas and leads to accidents.
Propeller applications
Hartzell Propeller developed their "Q-tip" propeller used on the Piper PA-42 Cheyenne and several other fixed-wing aircraft types by bending the blade tips back at a 90-degree angle to get the same thrust from a reduced diameter propeller disk; the reduced propeller tip speed reduces noise, according to the manufacturer. Modern scimitar propellers have increased sweepback at the tips, resembling a raked tip on an aircraft wing. | Wingtip device | Wikipedia | 509 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
Other applications
Some ceiling fans have wingtip devices. Fan manufacturer Big Ass Fans has claimed that their Isis fan, equipped with wingtip devices, has superior efficiency. However, for certain high-volume, low-speed designs, wingtip devices may not improve efficiency.
Another application of the same principle was introduced to the keel of the "America's Cup"- winning Australian yacht Australia II of 1982, designed by Ben Lexcen. | Wingtip device | Wikipedia | 87 | 313398 | https://en.wikipedia.org/wiki/Wingtip%20device | Technology | Aircraft components | null |
In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye. The SI unit of luminous intensity is the candela (cd), an SI base unit.
Measurement
Photometry deals with the measurement of visible light as perceived by human eyes. The human eye can only see light in the visible spectrum and has different sensitivities to light of different wavelengths within the spectrum. When adapted for bright conditions (photopic vision), the eye is most sensitive to yellow-green light at 555 nm. Light with the same radiant intensity at other wavelengths has a lower luminous intensity. The curve which represents the response of the human eye to light is a defined standard function or established by the International Commission on Illumination (CIE, for Commission Internationale de l'Éclairage) and standardized in collaboration with the ISO.
Luminous intensity of artificial light sources is typically measured using and a goniophotometer outfitted with a photometer or a spectroradiometer.
Relationship to other measures
Luminous intensity should not be confused with another photometric unit, luminous flux, which is the total perceived power emitted in all directions. Luminous intensity is the perceived power per unit solid angle. If a lamp has a 1 lumen bulb and the optics of the lamp are set up to focus the light evenly into a 1 steradian beam, then the beam would have a luminous intensity of 1 candela. If the optics were changed to concentrate the beam into 1/2 steradian then the source would have a luminous intensity of 2 candela. The resulting beam is narrower and brighter, though its luminous flux remains unchanged.
Luminous intensity is also not the same as the radiant intensity, the corresponding objective physical quantity used in the measurement science of radiometry.
Units
Like other SI base units, the candela has an operational definition—it is defined by the description of a physical process that will produce one candela of luminous intensity. By definition, if one constructs a light source that emits monochromatic green light with a frequency of 540 THz, and that has a radiant intensity of 1/683 watts per steradian in a given direction, that light source will emit one candela in the specified direction. | Luminous intensity | Wikipedia | 485 | 313418 | https://en.wikipedia.org/wiki/Luminous%20intensity | Physical sciences | Optics | Physics |
The frequency of light used in the definition corresponds to a wavelength in a vacuum of , which is near the peak of the eye's response to light. If the source emitted uniformly in all directions, the total radiant flux would be about , since there are 4 steradians in a sphere. A typical modern candle produces very roughly one candela while releasing heat at roughly .
Prior to the definition of the candela, a variety of units for luminous intensity were used in various countries. These were typically based on the brightness of the flame from a "standard candle" of defined composition, or the brightness of an incandescent filament of specific design. One of the best-known of these standards was the English standard: candlepower. One candlepower was the light produced by a pure spermaceti candle weighing one sixth of a pound and burning at a rate of 120 grains per hour. Germany, Austria, and Scandinavia used the Hefnerkerze, a unit based on the output of a Hefner lamp. In 1881, Jules Violle proposed the Violle as a unit of luminous intensity, and it was notable as the first unit of light intensity that did not depend on the properties of a particular lamp. All of these units were superseded by the definition of the candela.
Usage
The luminous intensity for monochromatic light of a particular wavelength is given by
where
is the luminous intensity in candelas (cd),
is the radiant intensity in watts per steradian (W/sr),
is the standard luminosity function.
If more than one wavelength is present (as is usually the case), one must sum or integrate over the spectrum of wavelengths present to get the luminous intensity: | Luminous intensity | Wikipedia | 351 | 313418 | https://en.wikipedia.org/wiki/Luminous%20intensity | Physical sciences | Optics | Physics |
The sperm whale or cachalot (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the pygmy sperm whale and dwarf sperm whale of the genus Kogia.
The sperm whale is a pelagic mammal with a worldwide range, and will migrate seasonally for feeding and breeding. Females and young males live together in groups, while mature males (bulls) live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade. A mature, healthy sperm whale has no natural predators, although calves and weakened adults are sometimes killed by pods of killer whales (orcas).
Mature males average in length, with the head representing up to one-third of the animal's length. Plunging to , it is the third deepest diving mammal, exceeded only by the southern elephant seal and Cuvier's beaked whale. The sperm whale uses echolocation and vocalization with source level as loud as 236 decibels (re 1 μPa m) underwater, the loudest of any animal. It has the largest brain on Earth, more than five times heavier than a human's. Sperm whales can live 70 years or more.
Sperm whales' heads are filled with a waxy substance called "spermaceti" (sperm oil), from which the whale derives its name. Spermaceti was a prime target of the whaling industry and was sought after for use in oil lamps, lubricants, and candles. Ambergris, a solid waxy waste product sometimes present in its digestive system, is still highly valued as a fixative in perfumes, among other uses. Beachcombers look out for ambergris as flotsam. Sperm whaling was a major industry in the 19th century, depicted in the novel Moby-Dick. The species is protected by the International Whaling Commission moratorium, and is listed as vulnerable by the International Union for Conservation of Nature.
Taxonomy and naming | Sperm whale | Wikipedia | 450 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Etymology
The name "sperm whale" is a clipping of "spermaceti whale". Spermaceti, originally mistakenly identified as the whales' semen, is the semi-liquid, waxy substance found within the whale's head.
(See "Spermaceti organ and melon" below.)
The sperm whale is also known as the "cachalot", which is thought to derive from the archaic French for 'tooth' or 'big teeth', as preserved for example in the word in the Gascon dialect (a word of either Romance
or Basque
origin).
The etymological dictionary of Corominas says the origin is uncertain, but it suggests that it comes from the Vulgar Latin 'sword hilts'. The word cachalot came to English via French from Spanish or Portuguese , perhaps from Galician/Portuguese 'big head'.
The term is retained in the Russian word for the animal, (), as well as in many other languages.
The scientific genus name Physeter comes from the Greek (), meaning 'blowpipe, blowhole (of a whale)', or – as a pars pro toto – 'whale'.
The specific name macrocephalus is Latinized from the Greek ( 'big-headed'), from () + ().
Its synonymous specific name catodon means 'down-tooth', from the Greek elements ('below') and ('tooth'); so named because it has visible teeth only in its lower jaw. (See "Jaws and teeth" below.)
Another synonym australasianus ('Australasian') was applied to sperm whales in the Southern Hemisphere. | Sperm whale | Wikipedia | 344 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Taxonomy
The sperm whale belongs to the order Cetartiodactyla, the order containing all cetaceans and even-toed ungulates. It is a member of the unranked clade Cetacea, with all the whales, dolphins, and porpoises, and further classified into Odontoceti, containing all the toothed whales and dolphins. It is the sole extant species of its genus, Physeter, in the family Physeteridae. Two species of the related extant genus Kogia, the pygmy sperm whale Kogia breviceps and the dwarf sperm whale K. sima, are placed either in this family or in the family Kogiidae. In some taxonomic schemes the families Kogiidae and Physeteridae are combined as the superfamily Physeteroidea (see the separate entry on the sperm whale family).
Swedish ichthyologist Peter Artedi described it as Physeter catodon in his 1738 work Genera piscium, from the report of a beached specimen in Orkney in 1693 and two beached in the Netherlands in 1598 and 1601. The 1598 specimen was near Berkhey.
The sperm whale is one of the species originally described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. He recognised four species in the genus Physeter. Experts soon realised that just one such species exists, although there has been debate about whether this should be named P. catodon or P. macrocephalus, two of the names used by Linnaeus. Both names are still used, although most recent authors now accept macrocephalus as the valid name, limiting catodon status to a lesser synonym. Until 1974, the species was generally known as P. catodon. In that year, however, Dutch zoologists Antonius M. Husson and Lipke Holthuis proposed that the correct name should be P. macrocephalus, the second name in the genus Physeter published by Linnaeus concurrently with P. catodon. | Sperm whale | Wikipedia | 419 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
This proposition was based on the grounds that the names were synonyms published simultaneously, and, therefore, the ICZN Principle of the First Reviser should apply. In this instance, it led to the choice of P. macrocephalus over P. catodon, a view re-stated in Holthuis, 1987. This has been adopted by most subsequent authors, although Schevill (1986 and 1987) argued that macrocephalus was published with an inaccurate description and that therefore only the species catodon was valid, rendering the principle of "First Reviser" inapplicable. The most recent version of ITIS has altered its usage from P. catodon to P. macrocephalus, following L. B. Holthuis and more recent (2008) discussions with relevant experts. Furthermore, The Taxonomy Committee of the Society for Marine Mammalogy, the largest international association of marine mammal scientists in the world, officially uses Physeter macrocephalus when publishing their definitive list of marine mammal species.
Biology
External appearance
The sperm whale is the largest toothed whale and is among the most sexually dimorphic of all cetaceans. Both sexes are about the same size at birth, but mature males are typically 30% to 50% longer and three times as massive as females.
Newborn sperm whales are usually between long. Female sperm whales are sexually mature at in length, whilst males are sexually mature at . Female sperm whales are physically mature at about in length and generally do not achieve lengths greater than . The largest female sperm whale measured up to long, and an individual of such size would have weighed about . Male sperm whales are physically mature at about in length, and larger males can generally achieve . An long male sperm whale is estimated to have weighed . By contrast, the second largest toothed whale (Baird's beaked whale) measures up to and weighs up to .
There are occasional reports of individual sperm whales achieving even greater lengths, with some historical claims reaching or exceeding . One example is the whale that sank the Essex (one of the incidents behind Moby-Dick), which was claimed to be . However, there is disagreement as to the accuracy of some of these claims, which are often considered exaggerations or as being measured along the curves of the body. | Sperm whale | Wikipedia | 466 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
An individual measuring was reported from a Soviet whaling fleet near the Kuril Islands in 1950 and is cited by some authors as the largest accurately measured. It has been estimated to weigh . In a review of size variation in marine megafauna, McClain and colleagues noted that the International Whaling Commission's data contained eight individuals larger than . The authors supported a male from the South Pacific in 1933 as the largest recorded. However, sizes like these are rare, with 95% of recorded sperm whales below 15.85 metres (52.0 ft).
In 1853, one sperm whale was reported at in length, with a head measuring . Large lower jawbones are held in the British Natural History Museum and the Oxford University Museum of Natural History, measuring and , respectively.
The average size of sperm whales has decreased over the years, probably due to pressure from whaling. Another view holds that exploitation by overwhaling had virtually no effect on the size of the bull sperm whales, and their size may have actually increased in current times on the basis of density dependent effects. Old males taken at Solander Islands were recorded to be extremely large and unusually rich in blubbers.
The sperm whale's unique body is unlikely to be confused with any other species. The sperm whale's distinctive shape comes from its very large, block-shaped head, which can be one-quarter to one-third of the animal's length. The S-shaped blowhole is located very close to the front of the head and shifted to the whale's left. This gives rise to a distinctive bushy, forward-angled spray.
The sperm whale's flukes (tail lobes) are triangular and very thick. Proportionally, they are larger than that of any other cetacean, and are very flexible. The whale lifts its flukes high out of the water as it begins a feeding dive. It has a series of ridges on the back's caudal third instead of a dorsal fin. The largest ridge was called the 'hump' by whalers, and can be mistaken for a dorsal fin because of its shape and size.
In contrast to the smooth skin of most large whales, its back skin is usually wrinkly and has been likened to a prune by whale-watching enthusiasts. Albinos have been reported.
Skeleton | Sperm whale | Wikipedia | 472 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The ribs are bound to the spine by flexible cartilage, which allows the ribcage to collapse rather than snap under high pressure. While sperm whales are well adapted to diving, repeated dives to great depths have long-term effects. Bones show the same avascular necrosis that signals decompression sickness in humans. Older skeletons showed the most extensive damage, whereas calves showed no damage. This damage may indicate that sperm whales are susceptible to decompression sickness, and sudden surfacing could be lethal to them.
Like that of all cetaceans, the spine of the sperm whale has reduced zygapophysial joints, of which the remnants are modified and are positioned higher on the vertebral dorsal spinous process, hugging it laterally, to prevent extensive lateral bending and facilitate more dorso-ventral bending. These evolutionary modifications make the spine more flexible but weaker than the spines of terrestrial vertebrates.
Like many cetaceans, the sperm whale has a vestigial pelvis that is not connected to the spine.
Like that of other toothed whales, the skull of the sperm whale is asymmetrical so as to aid echolocation. Sound waves that strike the whale from different directions will not be channeled in the same way. Within the basin of the cranium, the openings of the bony narial tubes (from which the nasal passages spring) are skewed towards the left side of the skull.
Jaws and teeth
The sperm whale's lower jaw is very narrow and underslung. The sperm whale has 18 to 26 teeth on each side of its lower jaw which fit into sockets in the upper jaw. The teeth are cone-shaped and weigh up to each. The teeth are functional, but do not appear to be necessary for capturing or eating squid, as well-fed animals have been found without teeth or even with deformed jaws. One hypothesis is that the teeth are used in aggression between males. Mature males often show scars which seem to be caused by the teeth. Rudimentary teeth are also present in the upper jaw, but these rarely emerge into the mouth. Analyzing the teeth is the preferred method for determining a whale's age. Like the age-rings in a tree, the teeth build distinct layers of cementum and dentine as they grow.
Brain | Sperm whale | Wikipedia | 478 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The sperm whale brain is the largest known of any modern or extinct animal, weighing on average about (with the smallest known weighing and the largest known weighing ), more than five times heavier than a human brain, and has a volume of about 8,000 cm3. Although larger brains generally correlate with higher intelligence, it is not the only factor. Elephants and dolphins also have larger brains than humans. The sperm whale has a lower encephalization quotient than many other whale and dolphin species, lower than that of non-human anthropoid apes, and much lower than that of humans.
The sperm whale's cerebrum is the largest in all mammalia, both in absolute and relative terms. The olfactory system is reduced, suggesting that the sperm whale has a poor sense of taste and smell. By contrast, the auditory system is enlarged. The pyramidal tract is poorly developed, reflecting the reduction of its limbs.
Biological systems
The sperm whale respiratory system has adapted to cope with drastic pressure changes when diving. The flexible ribcage allows lung collapse, reducing nitrogen intake, and metabolism can decrease to conserve oxygen. Between dives, the sperm whale surfaces to breathe for about eight minutes before diving again. Odontoceti (toothed whales) breathe air at the surface through a single, S-shaped blowhole, which is extremely skewed to the left. Sperm whales spout (breathe) 3–5 times per minute at rest, increasing to 6–7 times per minute after a dive. The blow is a noisy, single stream that rises up to or more above the surface and points forward and left at a 45° angle. On average, females and juveniles blow every 12.5 seconds before dives, while large males blow every 17.5 seconds before dives. A sperm whale killed south of Durban, South Africa, after a 1-hour, 50-minute dive was found with two dogfish (Scymnodon sp.), usually found at the sea floor, in its belly. | Sperm whale | Wikipedia | 417 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The sperm whale has the longest intestinal system in the world, exceeding 300 m in larger specimens. The sperm whale has a four-chambered stomach that is similar to ruminants. The first secretes no gastric juices and has very thick muscular walls to crush the food (since whales cannot chew) and resist the claw and sucker attacks of swallowed squid. The second chamber is larger and is where digestion takes place. Undigested squid beaks accumulate in the second chamber – as many as 18,000 have been found in some dissected specimens. Most squid beaks are vomited by the whale, but some occasionally make it to the hindgut. Such beaks precipitate the formation of ambergris.
In 1959, the heart of a 22 metric-ton (24 short-ton) male taken by whalers was measured to be , about 0.5% of its total mass. The circulatory system has a number of specific adaptations for the aquatic environment. The diameter of the aortic arch increases as it leaves the heart. This bulbous expansion acts as a windkessel, ensuring a steady blood flow as the heart rate slows during diving. The arteries that leave the aortic arch are positioned symmetrically. There is no costocervical artery. There is no direct connection between the internal carotid artery and the vessels of the brain. Their circulatory system has adapted to dive at great depths, as much as for up to 120 minutes. More typical dives are around and 35 minutes in duration. Myoglobin, which stores oxygen in muscle tissue, is much more abundant than in terrestrial animals. The blood has a high density of red blood cells, which contain oxygen-carrying haemoglobin. The oxygenated blood can be directed towards only the brain and other essential organs when oxygen levels deplete. The spermaceti organ may also play a role by adjusting buoyancy (see below). The arterial retia mirabilia are extraordinarily well-developed. The complex arterial retia mirabilia of the sperm whale are more extensive and larger than those of any other cetacean.
Senses
Spermaceti organ and melon | Sperm whale | Wikipedia | 458 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Atop the whale's skull is positioned a large complex of organs filled with a liquid mixture of fats and waxes called spermaceti. The purpose of this complex is to generate powerful and focused clicking sounds, the existence of which was proven by Valentine Worthington and William Schevill when a recording was produced on a research vessel in May 1959. The sperm whale uses these sounds for echolocation and communication.
The spermaceti organ is like a large barrel of spermaceti. Its surrounding wall, known as the case, is extremely tough and fibrous. The case can hold within it up to 1,900 litres of spermaceti. It is proportionately larger in males. This oil is a mixture of triglycerides and wax esters. It has been suggested that it is homologous to the dorsal bursa organ found in dolphins. The proportion of wax esters in the spermaceti organ increases with the age of the whale: 38–51% in calves, 58–87% in adult females, and 71–94% in adult males. The spermaceti at the core of the organ has a higher wax content than the outer areas. The speed of sound in spermaceti is 2,684 m/s (at 40 kHz, 36 °C), making it nearly twice as fast as in the oil in a dolphin's melon.
Below the spermaceti organ lies the "junk" which consists of compartments of spermaceti separated by cartilage. It is analogous to the melon found in other toothed whales. The structure of the junk redistributes physical stress across the skull and may have evolved to protect the head during ramming.
Running through the head are two air passages. The left passage runs alongside the spermaceti organ and goes directly to the blowhole, whilst the right passage runs underneath the spermaceti organ and passes air through a pair of phonic lips and into the distal sac at the very front of the nose. The distal sac is connected to the blowhole and the terminus of the left passage. When the whale is submerged, it can close the blowhole, and air that passes through the phonic lips can circulate back to the lungs. The sperm whale, unlike other odontocetes, has only one pair of phonic lips, whereas all other toothed whales have two, and it is located at the front of the nose instead of behind the melon. | Sperm whale | Wikipedia | 505 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
At the posterior end of this spermaceti complex is the frontal sac, which covers the concave surface of the cranium. The posterior wall of the frontal sac is covered with fluid-filled knobs, which are about 4–13 mm in diameter and separated by narrow grooves. The anterior wall is smooth. The knobbly surface reflects sound waves that come through the spermaceti organ from the phonic lips. The grooves between the knobs trap a film of air that is consistent whatever the orientation or depth of the whale, making it an excellent sound mirror.
The spermaceti organs may also help adjust the whale's buoyancy. It is hypothesized that before the whale dives, cold water enters the organ, and it is likely that the blood vessels constrict, reducing blood flow, and, hence, temperature. The wax therefore solidifies and reduces in volume. The increase in specific density generates a down force of about and allows the whale to dive with less effort. During the hunt, oxygen consumption, together with blood vessel dilation, produces heat and melts the spermaceti, increasing its buoyancy and enabling easy surfacing. However, more recent work has found many problems with this theory including the lack of anatomical structures for the actual heat exchange. Another issue is that if the spermaceti does indeed cool and solidify, it would affect the whale's echolocation ability just when it needs it to hunt in the depths.
Herman Melville's fictional story Moby-Dick suggests that the "case" containing the spermaceti serves as a battering ram for use in fights between males. A few famous instances include the well-documented sinking of the ships Essex and Ann Alexander by attackers estimated to weigh only one-fifth as much as the ships.
Eyes and vision | Sperm whale | Wikipedia | 372 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The sperm whale's eye does not differ greatly from those of other toothed whales except in size. It is the largest among the toothed whales, weighing about 170 g. It is overall ellipsoid in shape, compressed along the visual axis, measuring about 7×7×3 cm. The cornea is elliptical and the lens is spherical. The sclera is very hard and thick, roughly 1 cm anteriorly and 3 cm posteriorly. There are no ciliary muscles. The choroid is very thick and contains a fibrous tapetum lucidum. Like other toothed whales, the sperm whale can retract and protrude its eyes, thanks to a 2-cm-thick retractor muscle attached around the eye at the equator, but are unable to roll the eyes in their sockets.
According to Fristrup and Harbison (2002),
sperm whale's eyes afford good vision and sensitivity to light. They conjectured that sperm whales use vision to hunt squid, either by detecting silhouettes from below or by detecting bioluminescence. If sperm whales detect silhouettes, Fristrup and Harbison suggested that they hunt upside down, allowing them to use the forward parts of the ventral visual fields for binocular vision.
Sleeping
For some time researchers have been aware that pods of sperm whales may sleep for short periods, assuming a vertical position with their heads just below or at the surface, or head down. A 2008 study published in Current Biology recorded evidence that whales may sleep with both sides of the brain. It appears that some whales may fall into a deep sleep for about 7 percent of the time, most often between 6 p.m. and midnight.
Genetics
Sperm whales have 21 pairs of chromosomes (2n=42). The genome of live whales can be examined by recovering shed skin.
Vocalization complex
After Valentine Worthington and William E. Schevill confirmed the existence of sperm whale vocalization, further studies found that sperm whales are capable of emitting sounds at a source level of 230 decibels–making the sperm whale the loudest animal in the world. | Sperm whale | Wikipedia | 434 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Mechanism
When echolocating, the sperm whale emits a directionally focused beam of broadband clicks. Clicks are generated by forcing air through a pair of phonic lips (also known as "monkey lips" or "") at the front end of the nose, just below the blowhole. The sound then travels backwards along the length of the nose through the spermaceti organ. Most of the sound energy is then reflected off the frontal sac at the cranium and into the melon, whose lens-like structure focuses it. Some of the sound will reflect back into the spermaceti organ and back towards the front of the whale's nose, where it will be reflected through the spermaceti organ a third time. This back and forth reflection which happens on the scale of a few milliseconds creates a multi-pulse click structure.
This multi-pulse click structure allows researchers to measure the whale's spermaceti organ using only the sound of its clicks. Because the interval between pulses of a sperm whale's click is related to the length of the sound producing organ, an individual whale's click is unique to that individual. However, if the whale matures and the size of the spermaceti organ increases, the tone of the whale's click will also change. The lower jaw is the primary reception path for the echoes. A continuous fat-filled canal transmits received sounds to the inner ear.
The source of the air forced through the phonic lips is the right nasal passage. While the left nasal passage opens to the blow hole, the right nasal passage has evolved to supply air to the phonic lips. It is thought that the nostrils of the land-based ancestor of the sperm whale migrated through evolution to their current functions, the left nostril becoming the blowhole and the right nostril becoming the phonic lips.
Air that passes through the phonic lips passes into the distal sac, then back down through the left nasal passage. This recycling of air allows the whale to continuously generate clicks for as long as it is submerged.
Vocalization types
The sperm whale's vocalizations are all based on clicking, described in four types: the usual echolocation, creaks, codas, and slow clicks.
The usual echolocation click type is used in searching for prey. A creak is a rapid series of high-frequency clicks that sounds somewhat like a creaky door hinge. It is typically used when homing in on prey. | Sperm whale | Wikipedia | 508 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Slow clicks are heard only in the presence of males (it is not certain whether females occasionally make them). Males make a lot of slow clicks in breeding grounds (74% of the time), both near the surface and at depth, which suggests they are primarily mating signals. Outside breeding grounds, slow clicks are rarely heard, and usually near the surface.
Codas
The most distinctive vocalizations are codas, which are short rhythmic sequences of clicks, mostly numbering 3–12 clicks, in stereotyped patterns. They are classified using variations in the number of clicks, rhythm, and tempo.
Codas are the result of vocal learning within a stable social group, and are made in the context of the whales' social unit. "The foundation of sperm whale society is the matrilineally based social unit of ten or so females and their offspring. The members of the unit travel together, suckle each others' infants, and babysit them while mothers make long deep dives to feed." Over 70% of a sperm whale's time is spent independently foraging; codas "could help whales reunite and reaffirm their social ties in between long foraging dives."
While nonidentity codas are commonly used in multiple different clans, some codas express clan identity, and denote different patterns of travel, foraging, and socializing or avoidance among clans. In particular, whales will not group with whales of another clan even though they share the same geographical area. Statistically, as the clans' ranges become more overlapped, the distinction in clan identity coda usage becomes more pronounced. Distinctive codas identify seven clans described among the approximately 150,000 female sperm whales in the Pacific Ocean, and there are another four clans in the Atlantic. As "arbitrary traits that function as reliable indicators of cultural group membership," clan identity codas act as symbolic markers that modulate interactions between individuals.
Individual identity in sperm whale vocalizations is an ongoing scientific issue, however. A distinction needs to be made between cues and signals. Human acoustic tools can distinguish individual whales by analyzing micro-characteristics of their vocalizations, and the whales can probably do the same. This does not prove that the whales deliberately use some vocalizations to signal individual identity in the manner of the signature whistles that bottlenose dolphins use as individual labels.
Ecology
Distribution | Sperm whale | Wikipedia | 473 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Sperm whales are among the most cosmopolitan species. They prefer ice-free waters over deep. Although both sexes range through temperate and tropical oceans and seas, only adult males populate higher latitudes. Among several regions, such as along coastal waters of southern Australia, sperm whales have been considered to be locally extinct.
They are relatively abundant from the poles to the equator and are found in all the oceans. They inhabit the Mediterranean Sea, but not the Black Sea, while their presence in the Red Sea is uncertain. The shallow entrances to both the Black Sea and the Red Sea may account for their absence. The Black Sea's lower layers are also anoxic and contain high concentrations of sulphur compounds such as hydrogen sulphide. The first ever sighting off the coast of Pakistan was made in 2017. The first ever record off the west coast of the Korean Peninsula (Yellow Sea) was made in 2005. followed by one near Ganghwa Island in 2009.
Populations are denser close to continental shelves and canyons. Sperm whales are usually found in deep, off-shore waters, but may be seen closer to shore, in areas where the continental shelf is small and drops quickly to depths of . Coastal areas with significant sperm whale populations include the Azores and Dominica. In east Asian waters, whales are also observed regularly in coastal waters in places such as the Commander and Kuril Islands, Shiretoko Peninsula which is one of few locations where sperm whales can be observed from shores, off Kinkasan, vicinity to Tokyo Bay and the Bōsō Peninsula to the Izu and the Izu Islands, the Volcano Islands, Yakushima and the Tokara Islands to the Ryukyu Islands, Taiwan, the Northern Mariana Islands, and so forth. Historical catch records suggest there could have been smaller aggression grounds in the Sea of Japan as well. Along the Korean Peninsula, the first confirmed observation within the Sea of Japan, eight animals off Guryongpo, was made in 2004 since after the last catches of five whales off Ulsan in 1911, while nine whales were observed in the East China Sea side of the peninsula in 1999.
Grown males are known to enter surprisingly shallow bays to rest (whales will be in a state of rest during these occasions). Unique, coastal groups have been reported from various areas around the globe, such as near Scotland's coastal waters, and the Shiretoko Peninsula, off Kaikōura, in Davao Gulf. Such coastal groups were more abundant in pre-whaling days. | Sperm whale | Wikipedia | 504 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Genetic analysis indicates that the world population of sperm whales originated in the Pacific Ocean from a population of about 10,000 animals around 100,000 years ago, when expanding ice caps blocked off their access to other seas. In particular, colonization of the Atlantic was revealed to have occurred multiple times during this expansion of their range.
Diet
Sperm whales usually dive between , and sometimes , in search of food. Such dives can last more than an hour. They feed on several species, notably the giant squid, but also the colossal squid, octopuses, and fish such as demersal rays and sharks, but their diet is mainly medium-sized squid. Sperm whales may also possibly prey upon swordfish on rare occasions. Some prey may be taken accidentally while eating other items. Most of what is known about deep-sea squid has been learned from specimens in captured sperm whale stomachs, although more recent studies analysed faeces.
One study, carried out around the Galápagos, found that squid from the genera Histioteuthis (62%), Ancistrocheirus (16%), and Octopoteuthis (7%) weighing between were the most commonly taken. Battles between sperm whales and giant squid or colossal squid have never been observed by humans; however, white scars are believed to be caused by the large squid. One study published in 2010 collected evidence that suggests that female sperm whales may collaborate when hunting Humboldt squid. Tagging studies have shown that sperm whales hunt upside down at the bottom of their deep dives. It is suggested that the whales can see the squid silhouetted above them against the dim surface light.
An older study, examining whales captured by the New Zealand whaling fleet in the Cook Strait region, found a 1.69:1 ratio of squid to fish by weight. Sperm whales sometimes take sablefish and toothfish from long lines. Long-line fishing operations in the Gulf of Alaska complain that sperm whales take advantage of their fishing operations to eat desirable species straight off the line, sparing the whales the need to hunt. However, the amount of fish taken is very little compared to what the sperm whale needs per day. Video footage has been captured of a large male sperm whale "bouncing" a long line, to gain the fish. Sperm whales are believed to prey on the megamouth shark, a rare and large deep-sea species discovered in the 1970s. In one case, three sperm whales were observed attacking or playing with a megamouth. | Sperm whale | Wikipedia | 502 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Sperm whales have also been noted to feed on bioluminescent pyrosomes such as Pyrosoma atlanticum. It is thought that the foraging strategy of sperm whales for bioluminescent squids may also explain the presence of these light-emitting pyrosomes in the diet of the sperm whale.
The sharp beak of a consumed squid lodged in the whale's intestine may lead to the production of ambergris, analogous to the production of pearls in oysters. The irritation of the intestines caused by squid beaks stimulates the secretion of this lubricant-like substance. Sperm whales are prodigious feeders and eat around 3% of their body weight per day. The total annual consumption of prey by sperm whales worldwide is estimated to be about . In comparison, human consumption of seafood is estimated to be .
Sperm whales hunt through echolocation. Their clicks are among the most powerful sounds in the animal kingdom (see above). It has been hypothesised that it can stun prey with its clicks. Experimental studies attempting to duplicate this effect have been unable to replicate the supposed injuries, casting doubt on this idea. One study showing that sound pressure levels on the squid are more than an order of magnitude below levels required for debilitation, and therefore, precluding acoustic
stunning to facilitate prey capture.
Sperm whales, as well as other large cetaceans, help fertilise the surface of the ocean by consuming nutrients in the depths and transporting those nutrients to the oceans' surface when they defecate, an effect known as the whale pump. This fertilises phytoplankton and other plants on the surface of the ocean and contributes to ocean productivity and the drawdown of atmospheric carbon.
Life cycle
Sperm whales can live 70 years or more. They are a prime example of a species that has been K-selected, meaning their reproductive strategy is associated with stable environmental conditions and comprises a low birth rate, significant parental aid to offspring, slow maturation, and high longevity.
How they choose mates has not been definitively determined. Bulls will fight with each other over females, and males will mate with multiple females, making them polygynous, but they do not dominate the group as in a harem. Bulls do not provide paternal care to their offspring but rather play a fatherly role to younger bulls to show dominance. | Sperm whale | Wikipedia | 490 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Females become fertile at around 9 years of age. The oldest pregnant female ever recorded was 41 years old. Gestation requires 14 to 16 months, producing a single calf. Sexually mature females give birth once every 4 to 20 years (pregnancy rates were higher during the whaling era). Birth is a social event, as the mother and calf need others to protect them from predators. The other adults may jostle and bite the newborn in its first hours.
Lactation proceeds for 19 to 42 months, but calves, rarely, may suckle up to 13 years. Like that of other whales, the sperm whale's milk has a higher fat content than that of terrestrial mammals: about 36%, compared to 4% in cow milk. This gives it a consistency similar to cottage cheese, which prevents it from dissolving in the water before the calf can drink it. It has an energy content of roughly 3,840 kcal/kg, compared to just 640 kcal/kg in cow milk. Calves may be allowed to suckle from females other than their mothers.
Males become sexually mature at 18 years. Upon reaching sexual maturity, males move to higher latitudes, where the water is colder and feeding is more productive. Females remain at lower latitudes. Males reach their full size at about age 50.
Social behaviour
Relations within the species
Like elephants, females and their young live in matriarchal groups called pods, while bulls live apart. Bulls sometimes form loose bachelor groups with other males of similar age and size. As they grow older, they typically live solitary lives, only returning to the pod to socialize or to breed. Bulls have beached themselves together, suggesting a degree of cooperation which is not yet fully understood. The whales rarely, if ever, leave their group.
A social unit is a group of sperm whales who live and travel together over a period of years. Individuals rarely, if ever, join or leave a social unit. There is a huge variance in the size of social units. They are most commonly between six and nine individuals in size but can have more than twenty. Unlike orcas, sperm whales within a social unit show no significant tendency to associate with their genetic relatives. Females and calves spend about three-quarters of their time foraging and a quarter of their time socializing. Socializing usually takes place in the afternoon. | Sperm whale | Wikipedia | 473 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
When sperm whales socialize, they emit complex patterns of clicks called codas. They will spend much of the time rubbing against each other. Tracking of diving whales suggests that groups engage in herding of prey, similar to bait balls created by other species, though the research needs to be confirmed by tracking the prey.
Relations with other species
The most common natural predator of sperm whales is the orca (killer whale), but pilot whales and false killer whales sometimes harass them. Orcas prey on target groups of females with young, usually making an effort to extract and kill a calf. The females will protect their calves or an injured adult by encircling them. They may face inwards with their tails out (the 'marguerite formation', named after the flower). The heavy and powerful tail of an adult whale is potentially capable of delivering lethal blows. Alternatively, they may face outwards (the 'heads-out formation'). Other than sperm whales, southern right whales had been observed to perform similar formations. However, formations in non-dangerous situations have been recorded as well. Early whalers exploited this behaviour, attracting a whole unit by injuring one of its members. Such a tactic is described in Moby-Dick: "Say you strike a Forty-barrel-bull—poor devil! all his comrades quit him. But strike a member of the harem school, and her companions swim around her with every token of concern, sometimes lingering so near her and so long, as themselves to fall a prey."If the killer whale pod is large, its members may sometimes be able to kill adult female sperm whales and can at least injure an entire pod of sperm whales. Bulls have no predators, and are believed to be too large, powerful and aggressive to be threatened by killer whales. Solitary bulls are known to interfere and come to the aid of vulnerable groups nearby. However, the bull sperm whale, when accompanying pods of female sperm whales and their calves as such, may be reportedly unable to effectively dissuade killer whales from their attacks on the group, although the killer whales may end the attack sooner when a bull is present. | Sperm whale | Wikipedia | 436 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
However, male sperm whales have been observed to attack and intimidate killer whale pods in competitive feeding instances. An incident was filmed from a long-line trawler: a killer whale pod was systematically taking fish caught on the trawler's long lines (as the lines were being pulled into the ship) when a male sperm whale appeared to repeatedly charge the killer whale pod in an attempt to drive them away; it was speculated by the film crew that the sperm whale was attempting to access the same fish. The killer whales employed a tail outward and tail-slapping defensive position against the bull sperm whale similar to that used by female sperm whales against attacking killer whales. However, at some potential feeding sites, the killer whales may prevail over sperm whales even when outnumbered by the sperm whales. Some authors consider the killer whales "usually" behaviorally dominant over sperm whales but express that the two species are "fairly evenly matched", with the killer whales' greater aggression, more considerable biting force for their size and predatory prowess more than compensating for their smaller size.
Sperm whales are not known for forging bonds with other species, but it was observed that a bottlenose dolphin with a spinal deformity had been accepted into a pod of sperm whales. They are known to swim alongside other cetaceans such as humpback, fin, minke, pilot, and killer whales on occasion.
Parasites
Sperm whales can suffer from parasites.
Out of 35 sperm whales caught during the 1976–1977 Antarctic whaling season, all of them were infected by Anisakis physeteris (in their stomachs) and Phyllobothrium delphini (in their blubber).
Both whales with a placenta were infected with Placentonema gigantissima, potentially the largest nematode worm ever described.
Evolutionary history | Sperm whale | Wikipedia | 375 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Fossil record
Although the fossil record is poor, several extinct genera have been assigned to the clade Physeteroidea, which includes the last common ancestor of the modern sperm whale, pygmy sperm whales, dwarf sperm whales, and extinct physeteroids. These fossils include Ferecetotherium, Idiorophus, Diaphorocetus, Aulophyseter, Orycterocetus, Scaldicetus, Placoziphius, Zygophyseter and Acrophyseter. Ferecetotherium, found in Azerbaijan and dated to the late Oligocene (about ), is the most primitive fossil that has been found, which possesses sperm whale-specific features, such as an asymmetric rostrum ("beak" or "snout"). Most sperm whale fossils date from the Miocene period, . Diaphorocetus, from Argentina, has been dated to the early Miocene. Fossil sperm whales from the Middle Miocene include Aulophyseter, Idiorophus and Orycterocetus, all of which were found on the West Coast of the United States, and Scaldicetus, found in Europe and Japan. Orycterocetus fossils have also been found in the North Atlantic Ocean and the Mediterranean Sea, in addition to the west coast of the United States. Placoziphius, found in Europe, and Acrophyseter, from Peru, are dated to the late Miocene. | Sperm whale | Wikipedia | 310 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Fossil sperm whales differ from modern sperm whales in tooth count and the shape of the face and jaws. For example, Scaldicetus had a tapered rostrum. Genera from the Oligocene and early and middle Miocene, with the possible exception of Aulophyseter, had teeth in their upper jaws. Acrophyseter, from the late Miocene, also had teeth in both the upper and lower jaws as well as a short rostrum and an upward curving mandible (lower jaw). These anatomical differences suggest that fossil species may not have necessarily been deep-sea squid eaters such as the modern sperm whale, but that some genera mainly ate fish. Zygophyseter, dated from the middle to late Miocene and found in southern Italy, had teeth in both jaws and appears to have been adapted to feed on large prey, rather like the modern killer whale (orca). Other fossil sperm whales with adaptations similar to this are collectively known as killer sperm whales.
Two poorly known fossil species belonging to the modern genus Physeter have been recognized so far: P. antiquus (Neogene of France) and P. vetus (Neogene of eastern North America). Physeter vetus is very likely an invalid species, as the few teeth that were used to identify this species appear to be identical to those of another toothed whale, Orycterocetus quadratidens. | Sperm whale | Wikipedia | 296 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Phylogeny
The traditional view has been that Mysticeti (baleen whales) and Odontoceti (toothed whales) arose from more primitive whales early in the Oligocene period, and that the super-family Physeteroidea, which contains the sperm whale, dwarf sperm whale, and pygmy sperm whale, diverged from other toothed whales soon after that, over . From 1993 to 1996, molecular phylogenetics analyses by Milinkovitch and colleagues, based on comparing the genes of various modern whales, suggested that the sperm whales are more closely related to the baleen whales than they are to other toothed whales, which would have meant that Odontoceti were not monophyletic; in other words, it did not consist of a single ancestral toothed whale species and all its descendants. However, more recent studies, based on various combinations of comparative anatomy and molecular phylogenetics, criticised Milinkovitch's analysis on technical grounds and reaffirmed that the Odontoceti are monophyletic.
These analyses also confirm that there was a rapid evolutionary radiation (diversification) of the Physeteroidea in the Miocene period. The Kogiidae (dwarf and pygmy sperm whales) diverged from the Physeteridae (true sperm whales) at least .
Usage by humans
Sperm whaling
Spermaceti, obtained primarily from the spermaceti organ, and sperm oil, obtained primarily from the blubber in the body, were much sought after by 18th, 19th, and 20th century whalers. These substances found a variety of commercial applications, such as candles, soap, cosmetics, machine oil, other specialised lubricants, lamp oil, pencils, crayons, leather waterproofing, rust-proofing materials and many pharmaceutical compounds. Ambergris, a highly expensive, solid, waxy, flammable substance produced in the digestive system of sperm whales, was also sought as a fixative in perfumery. | Sperm whale | Wikipedia | 412 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Prior to the early eighteenth century, hunting was mostly by indigenous Indonesians. Legend has it that sometime in the early 18th century, around 1712, Captain Christopher Hussey, while cruising for right whales near shore, was blown offshore by a northerly wind, where he encountered a sperm whale pod and killed one. Although the story may not be true, sperm whales were indeed soon exploited by American whalers. Judge Paul Dudley, in his Essay upon the Natural History of Whales (1725), states that a certain Atkins, 10 or 12 years in the trade, was among the first to catch sperm whales sometime around 1720 off the New England coast.
There were only a few recorded instances during the first few decades (1709–1730s) of offshore sperm whaling. Instead, sloops concentrated on the Nantucket Shoals, where they would have taken right whales or went to the Davis Strait region to catch bowhead whales. By the early 1740s, with the advent of spermaceti candles (before 1743), American vessels began to focus on sperm whales. The diary of Benjamin Bangs (1721–1769) shows that, along with the bumpkin sloop he sailed, he found three other sloops flensing sperm whales off the coast of North Carolina in late May 1743. On returning to Nantucket in the summer 1744 on a subsequent voyage, he noted that "45 spermacetes are brought in here this day," another indication that American sperm whaling was in full swing. | Sperm whale | Wikipedia | 298 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
American sperm whaling soon spread from the east coast of the American colonies to the Gulf Stream, the Grand Banks, West Africa (1763), the Azores (1765), and the South Atlantic (1770s). From 1770 to 1775 Massachusetts, New York, Connecticut, and Rhode Island ports produced 45,000 barrels of sperm oil annually, compared to 8,500 of whale oil. In the same decade, the British began sperm whaling, employing American ships and personnel. By the following decade, the French had entered the trade, also employing American expertise. Sperm whaling increased until the mid-nineteenth century. Spermaceti oil was important in public lighting (for example, in lighthouses, where it was used in the United States until 1862, when it was replaced by lard oil, in turn replaced by petroleum) and for lubricating the machines (such as those used in cotton mills) of the Industrial Revolution. Sperm whaling declined in the second half of the nineteenth century, as petroleum came into broader use. In that sense, petroleum use may be said to have protected whale populations from even greater exploitation. Sperm whaling in the 18th century began with small sloops carrying only one or two whaleboats. The fleet's scope and size increased over time, and larger ships entered the fishery. In the late 18th century and early 19th century, sperm whaling ships sailed to the equatorial Pacific, the Indian Ocean, Japan, the coast of Arabia, Australia and New Zealand. Hunting could be dangerous to the crew, since sperm whales (especially bulls) will readily fight to defend themselves against attack, unlike most baleen whales. When dealing with a threat, sperm whales will use their huge head effectively as a battering ram. Arguably the most famous sperm whale counter-attack occurred on 20 November 1820, when a whale claimed to be about long rammed and sank the Nantucket whaleship Essex. Only 8 out of 21 sailors survived to be rescued by other ships. | Sperm whale | Wikipedia | 392 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The sperm whale's ivory-like teeth were often sought by 18th- and 19th-century whalers, who used them to produce inked carvings known as scrimshaw. 30 teeth of the sperm whale can be used for ivory. Each of these teeth, up to and across, are hollow for the first half of their length. Like walrus ivory, sperm whale ivory has two distinct layers. However, sperm whale ivory contains a much thicker inner layer. Though a widely practised art in the 19th century, scrimshaw using genuine sperm whale ivory declined substantially after the retirement of the whaling fleets in the 1880s.
Modern whaling was more efficient than open-boat whaling, employing steam-powered ships and exploding harpoons. Initially, modern whaling activity focused on large baleen whales, but as these populations were taken, sperm whaling increased. Spermaceti, the fine waxy oil produced by sperm whales, was in high demand. In both the 1941–1942 and 1942–1943 seasons, Norwegian expeditions took over 3,000 sperm whales off the coast of Peru alone. After World War II, whaling continued unabated to obtain oil for cosmetics and high-performance machinery, such as automobile transmissions.
The hunting led to the near-extinction of large whales, including sperm whales, until bans on whale oil use were instituted in 1972. The International Whaling Commission gave the species full protection in 1985, but hunting by Japan in the northern Pacific Ocean continued until 1988.
It is estimated that the historic worldwide population numbered 1,100,000 before commercial sperm whaling began in the early 18th century. By 1880, it had declined by an estimated 29 percent. From that date until 1946, the population appears to have partially recovered as whaling activity decreased, but after the Second World War, the population declined even further, to 33 per cent of the pre-whaling population. Between 184,000 and 236,000 sperm whales were killed by the various whaling nations in the 19th century, while in the 20th century, at least 770,000 were taken, the majority between 1946 and 1980. | Sperm whale | Wikipedia | 416 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Sperm whales increase levels of primary production and carbon export by depositing iron-rich faeces into surface waters of the Southern Ocean. The iron-rich faeces cause phytoplankton to grow and take up more carbon from the atmosphere. When the phytoplankton dies, it sinks to the deep ocean and takes the atmospheric carbon with it. By reducing the abundance of sperm whales in the Southern Ocean, whaling has resulted in an extra 2 million tonnes of carbon remaining in the atmosphere each year.
Remaining sperm whale populations are large enough that the species' conservation status is rated as vulnerable rather than endangered. However, the recovery from centuries of commercial whaling is a slow process, particularly in the South Pacific, where the toll on breeding-age males was severe.
Conservation status
The total number of sperm whales in the world is unknown, but is thought to be in the hundreds of thousands. The conservation outlook is brighter than for many other whales. Commercial whaling has ceased, and the species is protected almost worldwide, though records indicate that in the 11-year period starting from 2000, Japanese vessels have caught 51 sperm whales. Fishermen do not target sperm whales to eat, but long-line fishing operations in the Gulf of Alaska have complained about sperm whales "stealing" fish from their lines.
Since the 2000s , entanglement in fishing nets and collisions with ships represent the greatest threats to the sperm whale population. Other threats include ingestion of marine debris, ocean noise, and chemical pollution. The International Union for Conservation of Nature (IUCN) regards the sperm whale as being "vulnerable". The species is listed as endangered on the United States Endangered Species Act. | Sperm whale | Wikipedia | 335 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Sperm whales are listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements. It is also covered by the Agreement on the Conservation of Cetaceans in the Black Sea, Mediterranean Sea and Contiguous Atlantic Area (ACCOBAMS) and the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MOU).
The species is protected under Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). This makes commercial international trade (including in parts and derivatives) prohibited, with all other international trade strictly regulated through a system of permits and certificates.
Cultural importance
Rope-mounted teeth are important cultural objects throughout the Pacific. In New Zealand, the Māori know them as "rei puta"; such whale tooth pendants were rare objects because sperm whales were not actively hunted in traditional Māori society. Whale ivory and bone were taken from beached whales. In Fiji the teeth are known as tabua, traditionally given as gifts for atonement or esteem (called sevusevu), and were important in negotiations between rival chiefs. Friedrich Ratzel in The History of Mankind reported in 1896 that, in Fiji, whales' or cachalots' teeth were the most-demanded article of ornament or value. They occurred often in necklaces. Today the tabua remains an important item in Fijian life. The teeth were originally rare in Fiji and Tonga, which exported teeth, but with the Europeans' arrival, teeth flooded the market and this "currency" collapsed. The oversupply led in turn to the development of the European art of scrimshaw. | Sperm whale | Wikipedia | 443 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
Herman Melville's novel Moby-Dick is based on a true story about a sperm whale that attacked and sank the whaleship Essex. Melville associated the sperm whale with the Bible's Leviathan. The fearsome reputation perpetuated by Melville was based on bull whales' ability to fiercely defend themselves from attacks by early whalers, smashing whaling boats and, occasionally, attacking and destroying whaling ships.
In Jules Verne's 1870 novel Twenty Thousand Leagues Under the Seas, the Nautilus fights a group of "cachalots" (sperm whales) to protect a pod of southern right whales from their attacks. Verne portrays them as being savage hunters ("nothing but mouth and teeth").
The sperm whale was designated as the Connecticut state animal by the General Assembly in 1975. It was selected because of its specific contribution to the state's history and because of its present-day plight as an endangered species.
Watching sperm whales
Sperm whales are not the easiest of whales to watch, due to their long dive times and ability to travel long distances underwater. However, due to the distinctive look and large size of the whale, watching is increasingly popular. Sperm whale watchers often use hydrophones to listen to the clicks of the whales and locate them before they surface. Popular locations for sperm whale watching include the town of Kaikōura on New Zealand's South Island, Andenes and Tromsø in Arctic Norway; as well as the Azores, where the continental shelf is so narrow that whales can be observed from the shore, and Dominica where a long-term scientific research program, The Dominica Sperm Whale Project, has been in operation since 2005.
Plastic waste
The introduction of plastic waste to the ocean environment by humans is relatively new. From the 1970s, sperm whales have occasionally been found with pieces of plastic in their stomachs. | Sperm whale | Wikipedia | 372 | 313530 | https://en.wikipedia.org/wiki/Sperm%20whale | Biology and health sciences | Cetaceans | null |
The haddock (Melanogrammus aeglefinus) is a saltwater ray-finned fish from the family Gadidae, the true cods. It is the only species in the monotypic genus Melanogrammus. It is found in the North Atlantic Ocean and associated seas, where it is an important species for fisheries, especially in northern Europe, where it is marketed fresh, frozen and smoked; smoked varieties include the Finnan haddie and the Arbroath smokie. Other smoked versions include long boneless, the fileted side of larger haddock smoked in oak chips with the skin left on the fillet.
Description
The haddock has the elongated, tapering body shape typical of members of the cod family. It has a relatively small mouth which does not extend to below the eye; with the lower profile of the face being straight and the upper profile slightly rounded, this gives its snout a characteristic wedge-shaped profile. The upper jaw projects beyond the lower more so than in the Atlantic cod. There is a rather small barbel on the chin. There are three dorsal fins, the first being triangular in shape and these dorsal fins have 14 to 17 fin rays in the first, 20 to 24 in the second, and 19 to 22 in the third. There are also two anal fins and in these there are 21 to 25 fin rays in the first and 20 to 24 fin rays in the second. The anal and dorsal fins are all separated from each other. The pelvic fins are small with an elongated first fin ray. | Haddock | Wikipedia | 315 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
The upper side of the haddock's body varies in colour from dark grey brown to nearly black while the lower part of the body is dull silvery white. It has a distinctive black lateral line contrasting with the whitish background colour and which curves slightly over the pectoral fins. It also has a distinctive oval black blotch or ‘thumbprint’, sometimes called the "Devil's thumbprint", which sits between the lateral line and the pectoral fin, a feature which leads to the name of the genus Melanogrammus which derives from Greek "melanos" meaning "black" and "gramma" meaning letter or signal. The dorsal, pectoral, and caudal fins are dark grey in colour while the anal fins are pale matching the colour of the silvery sides, with black speckles at their bases. The pelvic fins are white with a variable amount of black spots. Occasionally there are differently coloured variants recorded which may be barred, golden on the back or lack the dark shoulder blotch.
The longest haddock recorded was in length and weighed . However, haddock are rarely over in length and the vast majority of haddocks caught in the United Kingdom measure between . In eastern Canada waters, haddock range in size from in length and in weight.
Distribution
The haddock has populations on either side of the north Atlantic but it is more abundant in the eastern Atlantic than it is on the North American side. In the north-east Atlantic it occurs from the Bay of Biscay north to Spitzbergen; however, it is most abundant north of the English Channel. It also occurs around Novaya Zemlya and the Barents Sea in the Arctic. The largest stocks are in the North Sea, off the Faroe Islands, off Iceland and the coast of Norway but these are discrete populations with little interchange between them. Off North America, the haddock is found from western Greenland south to Cape Hatteras, but the main commercially fished stock occurs from Cape Cod and the Grand Banks.
Habitat and biology | Haddock | Wikipedia | 419 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
The haddock is a demersal species which occurs at depths from , although it is most frequently recorded at . It is found over substrates made up of rock, sand, gravel or shells and it prefers temperatures of between . Off Iceland and in the Barents Sea, haddock undergo extensive migrations, but in the north western Atlantic its movements are more restricted, consisting of movements to and from their spawning areas. They reach sexual maturity at 4 years old in males and 5 years old in females, except for the population in the North Sea which matures at ages of 2 years in males and 3 years in females. The overall sex ratio is roughly 1:1, but in shallower areas, females predominate, while the males show a preference for waters further offshore.
The fecundity of the females varies with size: a fish of length bears 55,000 eggs while a fish at has 1,841,000 eggs. Spawning takes place from depths of around . In the northwestern Atlantic spawning lasts from January to July, although it does not occur simultaneously in all areas, and in the northeastern Atlantic the spawning season runs from February to June, peaking in March and April. The eggs are pelagic with a diameter of , and they take one to three weeks to hatch. Following metamorphosis, the past larval fish remain pelagic until they attain a length of around , when they settle to a demersal habit. Their growth rate shows considerable regional variation and fish at one year old can measure , at 2 years old , up to at 13 years old. Their lifespan is around 14 years. The most important spawning grounds are in the waters off the central coast of Norway, off the southwest of Iceland, and over the Georges Bank. The fish which spawn in inshore waters are normally smaller and younger fish than those which occur in offshore areas. The younger fish have a spawning season which is less than half of that of the larger and older stock offshore. Once hatched the larvae do not appear to travel far from their spawning grounds, however some larvae spawning off the west coast of Scotland are transported into the North Sea through the Fair Isle-Shetland Gap or to the northeast of Shetland. | Haddock | Wikipedia | 446 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
In their larval stages, haddock mainly feed on the immature stages of copepods, ostracods and limacina with their diet changing as they grow, moving on to larger pelagic prey such as amphipods, euphausiids, eggs of invertebrates, zoea larvae of decapods and increasing numbers of copepods. Once they have reached the settled, demersal, post-larval stage, they gradually switch from pelagic to benthic prey. Adults primarily feed on benthic invertebrates such as sea urchins, brittlestars, bivalves and worms, however, they will feed opportunistically on smaller fish such as capelin, sandeels and Norway pout. Juvenile haddock are an important prey for larger demersal fish, including other gadoids, while seals prey on the larger fish.
The recorded growth rates of haddock underwent significant change over the 30 to 40 years up to 2011. Growth has been more rapid in recent years, with haddock attaining adult size much earlier than was noted 30–40 years ago. However, the degree to which these larger, younger fish contribute to reproductive success of the population is unknown. The growth rates of haddock, however, have slowed in recent years. There is some evidence which indicates that these slower growth rates may be the result of an exceptionally large year class in 2003. The haddock stock periodically has higher than normal productivity; for example in 1962 and 1967, and to a lesser extent, 1974 and 1999. These result in a more southerly distribution of the fish and have a strong effect on the biomass of the spawning stock, but because of high fishing mortality, these revivals do not have any lasting effect on the population. In general, there was above average recruitment from the 1960s up to the early 1980s, similar to recruitment for Atlantic cod and whiting, this has been called the gadoid outburst. There was strong recruitment in 1999 but since then, the recruitment rate has been very low. | Haddock | Wikipedia | 412 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
Parasites
Cod and related species are plagued by parasites. For example, the cod worm, Lernaeocera branchialis, starts life as a copepod, a small, free-swimming crustacean larva. The first host used by cod worm is a flatfish or lumpsucker, which they capture with grasping hooks at the front of their bodies. They penetrate the lumpsucker with a thin filament which they use to suck its blood. The nourished cod worms then mate on the lumpsucker.
The female worm, with her now fertilized eggs, then finds a cod, or a cod-like fish such as a haddock or whiting. There, the worm clings to the gills while it metamorphoses into a plump, sinusoidal, wormlike body, with a coiled mass of egg strings at the rear. The front part of the worm's body penetrates the body of the cod until it enters the rear bulb of the host's heart. There, firmly rooted in the cod's circulatory system, the front part of the parasite develops like the branches of a tree, reaching into the main artery. In this way, the worm extracts nutrients from the cod's blood, remaining safely tucked beneath the cod's gill cover until it releases a new generation of offspring into the water.
Taxonomy and etymology
The haddock was first formally described as Gadus aeglefinus in 1758 by Carolus Linnaeus in the 10th edition of volume one of his Systema naturae with a type locality given as "European seas". In 1862 Theodore Nicholas Gill created the genus Melanogrammus with M. aeglefinus as its only species. The 5th edition of Fishes of the World classifies the haddock within the subfamily Gadinae, the typical cods, of the family Gadidae, which is within the superfamily Gadoidea of the order Gadiformes.
The generic name Melanogrammus means "black line", a reference to the black lateral line of this species. The specific name is a latinisation of the vernacular names egrefin and eglefin, used in France and England.
Fisheries | Haddock | Wikipedia | 451 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
Haddock is fished year-round using gear such as Danish seine nets, trawlers, long lines and gill nets and is often caught in mixed species fishery with other groundfish species such as cod and whiting. The main fishing grounds in the eastern Atlantic are in the Barents Sea, around Iceland, around the Faeroe Islands, in the North Sea, Celtic Sea, and in the English Channel. Landings in the eastern Atlantic have fluctuated around 200–350 thousand tonnes in the period 1980–2017. During the 1980s, the largest portion of the catch was taken at Rockall but from about 2000, the majority of the catch is caught in the Barents Sea. All the stocks in eastern Atlantic are assessed by ICES, which publish a recommendations on an annual basis for Total Allowable Catch.
In the western Atlantic the eastern Georges Bank haddock stock is jointly assessed on an annual basis by Canada and the United States and the stock is collaboratively managed through the Canada–United States Transboundary Management Guidance Committee, which was established in 2000. The commercial catch of haddock in North America was approximately 40–60 thousand tonnes per year between 1920 and 1960. This declined sharply in the late 1960s to between 5 and 30 thousand tonnes per year. Despite a few good years post-1970, landings have not returned to historical levels.
Haddock currently resides on the Greenpeace seafood red list due to concerns regarding the impact of bottom trawls on the marine environment. In contrast, Monterey Bay Aquarium considers haddock a "good alternative". Many haddock fisheries have been certified as sustainable by the Marine Stewardship Council. All seven stocks assessed in the eastern Atlantic are currently considered by ICES to be harvested sustainably. The haddock populations in the western Atlantic (offshore grounds of Georges Bank off New England and Nova Scotia) are also considered to be harvested sustainably.
As food | Haddock | Wikipedia | 382 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
Haddock is very popular as a food fish. It is sold fresh or preserved by smoking, freezing, drying, or to a small extent canning. Haddock, along with Atlantic cod and plaice, is one of the most popular fish used in British fish and chips. When fresh, the flesh of haddock is clean and white and its cooking is often similar to that of cod. A fresh haddock fillet will be firm and translucent and hold together well but less fresh fillets will become nearly opaque. Young, fresh haddock and cod fillets are often sold as scrod in Boston, Massachusetts; this refers to the size of the fish which have a variety of sizes, i.e., scrod, markets, and cows. Haddock is the predominant fish of choice in Scotland in a fish supper. It is also the main ingredient of Norwegian fishballs (fiskeboller). Unlike cod, haddock is not an appropriate fish for salting and preservation is more commonly effected by drying and smoking.
The smoking of haddock was highly refined in Grimsby. Traditional Grimsby smoked fish (mainly haddock, but sometimes cod) is produced in the traditional smokehouses in Grimsby, which are mostly family-run businesses that have developed their skills over many generations. Grimsby fish market sources its haddock from the North East Atlantic, principally Iceland, Norway and the Faroe Islands. These fishing grounds are sustainably managed and have not seen the large scale depreciation in fish stocks seen in EU waters.
One popular form of haddock is Finnan haddie which is named after the fishing village of Finnan or Findon in Scotland, where the fish was originally cold-smoked over smouldering peat. Finnan haddie is often poached in milk and served for breakfast.
The town of Arbroath on the east coast of Scotland produces the Arbroath smokie. This is a hot-smoked haddock which requires no further cooking before eating.
Smoked haddock is naturally an off-white colour and it is frequently dyed yellow, as are other smoked fish. Smoked haddock is the essential ingredient in the Anglo-Indian dish kedgeree, and also in the Scottish dish Cullen skink, a chowder-like soup. | Haddock | Wikipedia | 459 | 313822 | https://en.wikipedia.org/wiki/Haddock | Biology and health sciences | Acanthomorpha | null |
The Swiss Army knife (SAK; ) is a pocketknife, generally multi-tooled, now manufactured by Victorinox. The term "Swiss Army knife" was coined by American soldiers after World War II because they had trouble pronouncing the German word "", meaning "officer’s knife".
The Swiss Army knife generally has a drop-point main blade plus other types of blades and tools, such as a screwdriver, a can opener, a saw blade, a pair of scissors, and many others. These are folded into the handle of the knife through a pivot point mechanism. The handle is traditionally a red colour, with either a Victorinox or Wenger "cross" logo or, for Swiss military issue knives, the coat of arms of Switzerland. Other colours, textures, and shapes have appeared over the years.
Originating in Ibach, Switzerland, the Swiss Army knife was first produced in 1891 when the Karl Elsener company, which later became Victorinox, won the contract to produce the Swiss Army's Modell 1890 knife from the previous German manufacturer. In 1893, the Swiss cutlery company Paul Boéchat & Cie, which later became Wenger SA, received its first contract from the Swiss military to produce model 1890 knives; the two companies split the initial contract for provision of the knives and operated as separate enterprises from 1908. In 2005 Victorinox acquired Wenger. As an icon of the culture of Switzerland, both the design and the versatility of the knife have worldwide recognition. The term "Swiss Army knife" has acquired usage as a figure of speech indicating a multifaceted skillset.
History
Origins
The Swiss Army Knife was not the first multi-use pocket knife. In 1851, in Moby-Dick (chapter 107), Herman Melville mentions the "Sheffield contrivances, assuming the exterior – though a little swelled – of a common pocket knife; but containing, not only blades of various sizes, but also screwdrivers, cork-screws, tweezers, bradawls, pens, rulers, nail files and countersinkers."
During the late 1880s, the Swiss Army decided to purchase a new folding pocket knife for their soldiers. This knife was to be suitable for use by the army in opening canned food and for maintenance of the Swiss service rifle, the Schmidt–Rubin, which required a screwdriver for assembly and disassembly. | Swiss Army knife | Wikipedia | 497 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
In January 1891, the knife received the official designation Modell 1890. The knife had a blade, reamer, can opener, screwdriver, and grips made out of dark oak wood that some say was later partly replaced with ebony wood. At that time no Swiss company had the necessary production capacity, so the initial order for 15,000 knives was placed with the German knife manufacturer Wester & Co. from Solingen, Germany. These knives were delivered in October 1891.
In 1891, Karl Elsener, then owner of a company that made surgical equipment, set out to manufacture the knives in Switzerland itself. At the end of 1891 Elsener began production of the Modell 1890 knives, in direct competition with the Solingen company. He incurred financial losses doing so, as Wester & Co was able to produce the knives at a lower cost. Elsener was on the verge of bankruptcy when, in 1896, he developed an improved knife, intended for the use by officers, with tools attached on both sides of the handle using a special spring mechanism, allowing him to use the same spring to hold them in place. This new knife was patented on 12 June 1897, with a second, smaller cutting blade, a corkscrew, and wood fibre grips, under the name of Schweizer Offiziers- und Sportmesser ("Swiss officer's and sports knife"). While the Swiss military did not commission the knife, it was successfully marketed internationally, restoring Elsener's company to prosperity.
Elsener used a variation on the Swiss coat of arms to identify his knives beginning in 1909. With slight modifications, this is still the company logo. Also in 1909, on the death of his mother, Elsener used his mother's name Victoria, as a brand name, in her honour. In 1921 following the invention of stainless steel ( in French), Karl Elsener's son renamed the company to be Victorinox combining Victoria and inoxydable.
In 1893 the second industrial cutler of Switzerland, Paul Boéchat & Cie, headquartered in Delémont in the French-speaking region of Jura, started selling a similar product. Its general manager, Théodore Wenger, acquired the company and renamed it the Wenger Company.
Victorinox and Wenger | Swiss Army knife | Wikipedia | 465 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
In 1908 the Swiss government split the contract between Victorinox and Wenger, placing half the orders with each.
By mutual agreement, Wenger advertised "the Genuine Swiss Army Knife" and Victorinox used the slogan, "the Original Swiss Army Knife".
On 26 April 2005, Victorinox acquired Wenger, once again becoming the sole supplier of knives to the military of Switzerland. Victorinox at first kept the Wenger brand intact, but on 30 January 2013, the company announced that the Wenger brand of knives would be abandoned in favour of Victorinox.
The press release stated that Wenger's factory in Delémont would continue to produce knives and all employees at this site will retain their jobs. They further elaborated that an assortment of items from the Wenger line-up will remain in production under the Victorinox brand name. Wenger's US headquarters will be merged with Victorinox's location in Monroe, Connecticut. Wenger's watch and licensing business will continue as a separate brand: SwissGear.
Up until 2008 Victorinox AG and Wenger SA supplied about 50,000 knives to the military of Switzerland each year, and manufactured many more for export, mostly to the United States. Commercial knives can be distinguished by their cross logos; the Victorinox cross logo is surrounded by a shield while the Wenger cross logo is surrounded by a slightly rounded square.
Victorinox registered the words "Swiss Army" and "Swiss Military" as a trademark in the US and was sued at Bern cantonal commercial court by the Swiss Confederacy (represented by Armasuisse, the authority representing the actual Swiss military), in October 2018. After an initial hearing Victorinox agreed to cede the registration in the United States of the term "Swiss military" to Armasuisse in return for an exclusive licence to market perfumes under the same name.
Features, tools, and parts
Tools and components
There are various models of the Swiss Army knife with different tool combinations.
Though Victorinox does not provide custom knives, they have produced many different variations to suit individual users, with the Wenger company producing even more model variations. | Swiss Army knife | Wikipedia | 441 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
Common main layer tools:
Large blade - With 'VICTORINOX SWISS MADE' tang stamp on Victorinox blades since 2005
Small blade
Nail file
Scissors (sharpened to a 65° angle)
Wood saw
Metal file or metal saw with nail file
Magnifying glass
Phillips screwdriver
Fish scaler / hook disgorger / ruler in cm and inches
Pliers / wire cutter / wire crimper
Can opener / 3 mm slot screwdriver
Bottle opener / 6 mm slot screwdriver with wire stripper
Other main layer tools:
LED light
USB flash drive
Hoof cleaner
Shackle opener / marlinspike
Electrician's blade / wire scraper
Pruning blade
Pharmaceutical spatula (cuticle pusher)
Cyber Tool (bit driver)
Combination tool containing cap opener / can opener / 5 mm slot screwdriver with wire stripper
Back layer tools:
Corkscrew or Phillips driver
Reamer
Multipurpose hook with nail file
2mm slotted screwdriver
Chisel
Mini screwdriver (screws within the corkscrew)
Keyring
Scale tools:
Tweezers
Toothpick
Pressurised ballpoint pen (with a retractable version on smaller models, which can be used to set DIP switches)
Stainless steel pin
Digital clock / alarm / timer / altimeter / thermometer / barometer
Three Victorinox SAK models had a butane lighter: the SwissFlame, the CampFlame and the SwissChamp XXLT, first introduced in 2002 and discontinued in 2005. The models were never sold in the United States due to lack of safety features. They used a standard piezoelectric ignition system for easy ignition, with adjustable flame; they and were designed for operation at altitudes up to above sea level and continuous operation of 10 minutes. | Swiss Army knife | Wikipedia | 360 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
In January 2010, Victorinox announced the Presentation Master models, released in April 2010. The technological tools included a laser pointer, and detachable flash drive with fingerprint reader. Victorinox now sells an updated version called the Slim Jetsetter, with "a premium software package that provides ultra secure data encryption, automatic backup functionality, secure web surfing capabilities, file and email synchronization between the drive and multiple computers, Bluetooth pairing and much more. On the hardware side of things, biometric fingerprint technology, laser pointers, LED lights, Bluetooth remote control and of course, the original Swiss Army Knife implements – blade, scissors, nail file, screwdriver, key ring and ballpoint pen are standard. **Not every feature is available on every model within the collection."
In 2006, Wenger produced a knife called "The Giant" that included every implement the company ever made, with 87 tools and 141 different functions. It was recognized by Guinness World Records as the world's most multifunctional penknife. It retails for about €798 or $US1000, though some vendors charge much higher prices.
In the same year, Victorinox released the SwissChamp XAVT, consisting of 118 parts and 80 functions with a retail price of $425. The Guinness Book of Records recognizes a unique 314-blade Swiss Army-style knife made in 1991 by Master Cutler Hans Meister as the world's largest penknife, weighing .
Locking mechanisms
Some Swiss Army knives have locking blades to prevent accidental closure. Wenger was the first to offer a "PackLock" for the main blade on several of their standard 85mm models. Several large Wenger and Victorinox models have a locking blade secured by a slide lock that is operated with an unlocking-button integrated in the scales. Some Victorinox 111 mm series knives have a double liner lock that secures the cutting blade and large slotted screwdriver/cap opener/wire stripper combination tool designed towards prying.
Design and materials
Rivets and flanged bushings made from brass hold together all machined steel parts and other tools, separators and the scales. The rivets are made by cutting and pointing appropriately sized bars of solid brass.
The separators between the tools have been made from aluminium alloy since 1951. This makes the knives lighter. Previously these separating layers were made of nickel-silver. | Swiss Army knife | Wikipedia | 503 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
The martensitic stainless steel alloy used for the cutting blades is optimized for high toughness and corrosion resistance and has a composition of 15% chromium, 0.60% silicon, 0.52% carbon, 0.50% molybdenum, and 0.45% manganese and is designated X55CrMo14 or DIN 1.4110 according to Victorinox. After a hardening process at 1040 °C and annealing at 160 °C the blades achieve an average hardness of 56 HRC. This steel hardness is suitable for practical use and easy resharpening, but less than achieved in stainless steel alloys used for blades optimized for high wear resistance. According to Victorinox the martensitic stainless steel alloy used for the other parts is X39Cr13 (aka DIN 1.4031, AISI/ASTM 420) and for the springs X20Cr13 (aka DIN 1.4021, but still within AISI/ASTM 420).
The steel used for the wood saws, scissors and nail files has a steel hardness of HRC 53, the screwdrivers, tin openers and awls have a hardness of HRC 52, and the corkscrew and springs have a hardness of HRC 49.
The metal saws and files, in addition to the special case hardening, are also subjected to a hard chromium plating process so that iron and steel can also be filed and cut. | Swiss Army knife | Wikipedia | 303 | 313833 | https://en.wikipedia.org/wiki/Swiss%20Army%20knife | Technology | Knives | null |
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