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14,500 | The championship was originally due to start in March, but the start was postponed until July in response to the COVID-19 pandemic. The season was due to be contested over a record of 22 Grands Prix, but as some races were cancelled and new races were added to replace them, a total of 17 races were run. The season star... | https://en.wikipedia.org/wiki?curid=58993617 |
14,501 | Lewis Hamilton and Mercedes entered the season as the reigning World Drivers' and World Constructors' champions respectively, after they both won their sixth championship in 2019. At the Emilia Romagna Grand Prix, Mercedes secured their seventh consecutive Constructors' Championship making them the only team to win sev... | https://en.wikipedia.org/wiki?curid=58993617 |
14,502 | The following teams and drivers competed in the 2020 World Championship. All teams competed with tyres supplied by Pirelli. | https://en.wikipedia.org/wiki?curid=58993617 |
14,503 | Across the season, four drivers drove as a test or third driver in free practice sessions. Jack Aitken and Roy Nissany both drove for Williams at one and three Grands Prix respectively, Robert Kubica drove for Alfa Romeo Racing at five Grands Prix and Mick Schumacher drove for Haas at one Grand Prix. | https://en.wikipedia.org/wiki?curid=58993617 |
14,504 | Schumacher and Callum Ilott were entered to appear in the first practice session for the , driving for Alfa Romeo Racing and Haas, respectively, but the session was cancelled due to bad weather conditions. | https://en.wikipedia.org/wiki?curid=58993617 |
14,505 | Red Bull GmbH, the parent company of Red Bull Racing and Scuderia Toro Rosso, renamed Toro Rosso as "Scuderia AlphaTauri". The team uses the constructor name "AlphaTauri". The name is derived from Red Bull's AlphaTauri fashion brand. | https://en.wikipedia.org/wiki?curid=58993617 |
14,506 | After a year's absence, Esteban Ocon returned to racing in Formula One after signing a contract with Renault, replacing Nico Hülkenberg. Robert Kubica left Williams at the end of the 2019 championship and joined Alfa Romeo Racing as a reserve driver. Nicholas Latifi, the 2019 Formula 2 Championship runner-up, replaced ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,507 | A day before the British Grand Prix weekend, Racing Point driver Sergio Pérez tested positive for COVID-19 and was ruled out of the race weekend. After seeking clarification from Public Health England, Racing Point stated that they intended to let Pérez race in the 70th Anniversary Grand Prix pending a negative coronav... | https://en.wikipedia.org/wiki?curid=58993617 |
14,508 | After Romain Grosjean suffered burns to his hands following a crash at the Bahrain Grand Prix, Haas promoted test driver Pietro Fittipaldi to make his debut at the Sakhir Grand Prix. Grosjean also missed the Abu Dhabi Grand Prix because of his recovery after the crash in Bahrain; Fittipaldi raced again for the team. Le... | https://en.wikipedia.org/wiki?curid=58993617 |
14,509 | Twenty-two Grands Prix were originally scheduled for the 2020 World Championship. However, the COVID-19 pandemic resulted in numerous race cancellations and postponements. A rescheduled calendar consisted of seventeen Grands Prix, nine from the original 2020 calendar and eight other Grands Prix, while the other thirtee... | https://en.wikipedia.org/wiki?curid=58993617 |
14,510 | The following rounds were included on the original calendar published by the World Motor Sport Council, but were cancelled in response to the COVID-19 pandemic: | https://en.wikipedia.org/wiki?curid=58993617 |
14,511 | After purchasing the commercial rights to the sport from CVC Capital Partners in January 2017, Liberty Media announced plans to expand the Formula One calendar using a concept they termed "destination races" and modelled on the Singapore Grand Prix. Under the "destination races" model, Grands Prix would be established ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,512 | Liberty Media initially expected that the 2020 calendar would consist of twenty-one Grands Prix and that any new races would come at the expense of existing events, but later negotiated an agreement with the teams to allow up to twenty-two Grands Prix. Several further changes were made between the 2019 and 2020 calenda... | https://en.wikipedia.org/wiki?curid=58993617 |
14,513 | Teams were allowed to use an additional MGU-K compared to 2019 to compensate for the increased demands of contesting the originally planned twenty-two races. | https://en.wikipedia.org/wiki?curid=58993617 |
14,514 | Drivers who participated in free practice sessions were eligible for additional FIA Super Licence points. Any driver who completed a minimum during a free practice session received an additional Super Licence point on the condition that they do not commit a driving infraction. Drivers could only accrue ten Super Licenc... | https://en.wikipedia.org/wiki?curid=58993617 |
14,515 | As a result of what was then planned to be an expanded calendar, the two pre-season tests which took place at Circuit de Barcelona-Catalunya were reduced in length from four days to three days each, whilst the two in-season tests that took place at Bahrain International Circuit and Circuit de Barcelona-Catalunya in 201... | https://en.wikipedia.org/wiki?curid=58993617 |
14,516 | The rules surrounding jump starts and the weighbridge were relaxed with the race stewards able to hand out less severe punishments for missing the weighbridge and jump starts. | https://en.wikipedia.org/wiki?curid=58993617 |
14,517 | In order to reduce the risk of punctures, the last of the front wing could no longer contain any metal. Brake ducts could no longer be outsourced and must be made and designed by the team. The amount of fuel that could be outside of the fuel tank was reduced from to . A decrease in electronic driver aids meant that dri... | https://en.wikipedia.org/wiki?curid=58993617 |
14,518 | From the Italian Grand Prix, drivers were only allowed to run one engine mode from the start of qualifying to the end of the race. However, drivers were still allowed to use electrical power for the powertrain throughout the race weekend. | https://en.wikipedia.org/wiki?curid=58993617 |
14,519 | The season was heavily disrupted by the COVID-19 pandemic, with an announcement prior to the start of the championship that the Chinese Grand Prix would be postponed due to the early COVID-19 outbreak in the country. | https://en.wikipedia.org/wiki?curid=58993617 |
14,520 | Italian-based teams Ferrari and AlphaTauri expressed concern about the spread of the disease and its effect on the championship. As Italy suffered one of the worst outbreaks of the virus, both teams were concerned about the ability of their staff to leave the quarantine zone established in northern Italy and to enter h... | https://en.wikipedia.org/wiki?curid=58993617 |
14,521 | Ross Brawn, the managing director of the sport, announced that Grands Prix would not go ahead if a team were blocked from entering a host nation, but that events could go ahead if a team voluntarily chose not to enter a host nation. In early March, organisers of the Bahrain Grand Prix stated that the event would be "pa... | https://en.wikipedia.org/wiki?curid=58993617 |
14,522 | The season-opening Australian Grand Prix was expected to go ahead and all teams and drivers arrived at the venue as planned. Three days before the race was due to take place, McLaren announced their withdrawal from the event after a team member tested positive for the virus. This led to the Grand Prix being cancelled a... | https://en.wikipedia.org/wiki?curid=58993617 |
14,523 | Formula One and the FIA released a joint statement saying that they "expect to begin the Championship in Europe at the end of May" but that this timeline "will be regularly reviewed". On 19 March, the FIA announced that the Dutch, Spanish and Monaco Grands Prix had all been postponed indefinitely due to the pandemic. I... | https://en.wikipedia.org/wiki?curid=58993617 |
14,524 | In early April, organisers of the Canadian Grand Prix announced the race's postponement. Later in the month, the French Grand Prix organisers confirmed that the race would not be held in 2020, and the managing director of Silverstone Circuit stated that should the British Grand Prix go ahead, it would be without specta... | https://en.wikipedia.org/wiki?curid=58993617 |
14,525 | The Dutch Grand Prix was cancelled entirely in late May, with organisers of the event stating that they would prefer to host the revived race with spectators in attendance in 2021 rather than without spectators in 2020. Formula One confirmed the cancellation of the Azerbaijan, Singapore and Japanese Grands Prix in June... | https://en.wikipedia.org/wiki?curid=58993617 |
14,526 | The annual summer break, where factories shut down for two weeks, was brought forward from August to March and April. Teams nominated a three-week period to close with the aim of making room for races later in the year. At the end of March, it was announced that for the first time the factory shut-down would additional... | https://en.wikipedia.org/wiki?curid=58993617 |
14,527 | In March, teams agreed that the 2020 Championship could run into early 2021 to ensure the running of as many races as possible. Such a move would also ensure that eight Grands Prix could be held, over three different continents, thereby meeting the minimum number of races needed for the season to qualify as a World Cha... | https://en.wikipedia.org/wiki?curid=58993617 |
14,528 | In early April, Ross Brawn suggested that a rescheduled calendar of 18 or 19 races would be possible should racing begin in July, and that the opening round "is most likely to be in Europe", potentially without spectators. He also raised the possibility of Grand Prix events being reduced to two days in order to ease pr... | https://en.wikipedia.org/wiki?curid=58993617 |
14,529 | In a statement in late April, Formula One CEO Chase Carey declared the intention to begin the season on 5 July and a target to hold between 15 and 18 races overall. In June, the first eight races of a rescheduled calendar were confirmed, with the season expected to begin on 5 July with the Austrian Grand Prix. This rev... | https://en.wikipedia.org/wiki?curid=58993617 |
14,530 | On 10 July, the Russian Grand Prix was re-added to the calendar on its originally scheduled date, and the first Tuscan Grand Prix was announced at the Mugello Circuit, the first time the circuit would host a Formula One World Championship race. Later in July, the return of the Nürburgring and the Autodromo Internaziona... | https://en.wikipedia.org/wiki?curid=58993617 |
14,531 | In August, it was announced that Formula One would return to Istanbul Park for the first Turkish Grand Prix since the season, together with the debut of the Sakhir Grand Prix, to be held at the Bahrain International Circuit, using the configuration of the track called "Outer Circuit". They join the rescheduled Bahrain ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,532 | Of the races and dates on the original calendar, only four races, the Austrian, Belgian, Italian and Russian Grands Prix kept their original dates. | https://en.wikipedia.org/wiki?curid=58993617 |
14,533 | The pandemic required changes to the format of a race weekend, which included abandoning the drivers' parade and pre-race assembly for the host venue's national anthem. A modified podium ceremony was planned for after races. The FIA introduced limits to the number of team personnel who could be on the starting grid to ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,534 | In June, Formula One launched the "We Race As One" initiative to fight racism, global inequity and the impact of COVID-19. The initiative used a rainbow logo, with the colours of all ten Formula One teams, also with the #WeRaceAsOne hashtag, and featured prominent "We Race As One" branding on vehicles (including the sa... | https://en.wikipedia.org/wiki?curid=58993617 |
14,535 | Ahead of the season opening Austrian Grand Prix, Red Bull launched a protest against the Mercedes F1 W11's dual axis steering, a system where the driver can adjust the toe of the car by pulling and pushing on the steering wheel. The system was found to be legal for 2020, but it would be banned by the FIA from 2021 onwa... | https://en.wikipedia.org/wiki?curid=58993617 |
14,536 | After the Styrian Grand Prix, Renault launched a protest against the brake ducts of Racing Point's car, the RP20, alleging that Racing Point had copied the brake ducts from the Mercedes F1 W10, the car used in 2019 by Mercedes. Similar protests would be launched after the Hungarian and British Grands Prix with the verd... | https://en.wikipedia.org/wiki?curid=58993617 |
14,537 | Racing Point, Ferrari, McLaren, Renault and Williams had all indicated an intention to appeal the stewards decision with Racing Point trying to clear their name and Ferrari, McLaren, Williams and Renault appealing for a tougher sanction. Ferrari, Renault and Racing Point confirmed their appeal, while Williams and McLar... | https://en.wikipedia.org/wiki?curid=58993617 |
14,538 | The delayed season started with the Austrian Grand Prix. Valtteri Bottas, driving for Mercedes, took pole position, ahead of his teammate Lewis Hamilton and Red Bull's Max Verstappen; however, Hamilton was given a three-place grid penalty, since he did not slow sufficiently when yellow flags were waved following a smal... | https://en.wikipedia.org/wiki?curid=58993617 |
14,539 | The inaugural Styrian Grand Prix was won by Hamilton ahead of Bottas and Verstappen. The Hungarian Grand Prix started with a slippery track. Verstappen slid into the barrier on his way to the grid and broke his steering axis, but his mechanics managed to repair the car before the race start. The race winner was Hamilto... | https://en.wikipedia.org/wiki?curid=58993617 |
14,540 | Hamilton won the British Grand Prix despite his left-front tyre delaminating in the middle of the last lap. Verstappen finished second with Leclerc in third. Bottas had a puncture which resulted in him finishing in eleventh. Daniil Kvyat had a puncture at high speed entering Maggotts corner which resulted in a big cras... | https://en.wikipedia.org/wiki?curid=58993617 |
14,541 | The Belgian Grand Prix was won by Lewis Hamilton, who led every lap and won by 8 seconds over teammate Valtteri Bottas who finished second ahead of Max Verstappen. Daniel Ricciardo finished fourth, setting the fastest lap on the last lap. On lap 11, Antonio Giovinazzi crashed at Campus corner; one of the wheels of his ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,542 | The Italian Grand Prix was won by Pierre Gasly after a red flag caused by Charles Leclerc. This was his and AlphaTauri's first race victory. The race marked the first time since Kimi Räikkönen won the 2013 Australian Grand Prix driving for Lotus F1 that the race winner did not drive for Ferrari, Mercedes, or Red Bull a... | https://en.wikipedia.org/wiki?curid=58993617 |
14,543 | The inaugural Tuscan Grand Prix, Ferrari's 1000th Grand Prix start, resulted in Hamilton's sixth race win of the season, and Mercedes's third 1–2 finish. Bottas overtook Hamilton into turn one before a major collision at turn two caused the retirement of both Verstappen (who had fallen from 3rd to 14th due to a power i... | https://en.wikipedia.org/wiki?curid=58993617 |
14,544 | At the Russian Grand Prix, Hamilton started on pole, but two separate five-second penalties for practice starts outside the designated area meant he finished third; teammate Bottas won the Grand Prix with Verstappen in second. | https://en.wikipedia.org/wiki?curid=58993617 |
14,545 | At the inaugural Eifel Grand Prix, five cars retired in the forms of Russell, Esteban Ocon, Albon, Lando Norris and Bottas, who had started from pole. Hamilton took first place after Bottas locked up into turn 1 on lap 13. Hamilton would go on to win the race, his 7th win this season. Ricciardo claimed his first podium... | https://en.wikipedia.org/wiki?curid=58993617 |
14,546 | At the Portuguese Grand Prix, Hamilton took his 92nd win, taking the record for most wins that had been held by Michael Schumacher. Bottas would finish second in the race, twenty-five seconds behind his teammate, with Verstappen finishing third. | https://en.wikipedia.org/wiki?curid=58993617 |
14,547 | At the inaugural Emilia Romagna Grand Prix, Lewis Hamilton won from Valtteri Bottas and Daniel Ricciardo who picked up his second podium of the season. Max Verstappen had a puncture from second, putting him out of the race. Mercedes won their seventh consecutive Constructor World Championship. | https://en.wikipedia.org/wiki?curid=58993617 |
14,548 | The Turkish Grand Prix saw Hamilton claim his seventh world title with a race win, equalling Michael Schumacher's record for the most Formula One world titles. He finished on the podium with Sergio Pérez and Sebastian Vettel, whilst in qualifying, Lance Stroll claimed his maiden pole position in rainy conditions. | https://en.wikipedia.org/wiki?curid=58993617 |
14,549 | At the Bahrain Grand Prix, Hamilton claimed his 11th win of the year, followed by Verstappen and Alexander Albon in second and third. The race was marred by a serious accident involving Haas driver Romain Grosjean, who hit a barrier at the start of the race after making contact with the AlphaTauri of Daniil Kvyat. Gros... | https://en.wikipedia.org/wiki?curid=58993617 |
14,550 | Hamilton was ruled out of the Sakhir Grand Prix after testing positive for the coronavirus and was replaced by Williams' George Russell. Russell impressed by taking the lead from new teammate and pole-sitter Bottas and led for 59 laps, before being taken out of contention by first a tyre mix-up by Mercedes and then a l... | https://en.wikipedia.org/wiki?curid=58993617 |
14,551 | At the Abu Dhabi Grand Prix, Hamilton returned for the last race of the season after testing negative for the coronavirus. Verstappen took the pole position and his 10th win in Formula One ahead of Bottas and Hamilton, who finished second and third, respectively. This race was the last for Vettel at Ferrari, after six ... | https://en.wikipedia.org/wiki?curid=58993617 |
14,552 | Points are awarded to the top ten classified drivers and the driver who set the fastest lap. The driver with the fastest lap has to be within the top 10 to receive the point. In the case of a tie on points a countback system is used where the driver with the best results is ranked higher, if the best result is identica... | https://en.wikipedia.org/wiki?curid=58993617 |
14,553 | Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segmen... | https://en.wikipedia.org/wiki?curid=19827221 |
14,554 | The haemocoel, an arthropod's internal cavity, through which its haemolymph – analogue of blood – circulates, accommodates its interior organs; it has an open circulatory system. Like their exteriors, the internal organs of arthropods are generally built of repeated segments. Their nervous system is "ladder-like", with... | https://en.wikipedia.org/wiki?curid=19827221 |
14,555 | Arthropods use combinations of compound eyes and pigment-pit ocelli for vision. In most species, the ocelli can only detect the direction from which light is coming, and the compound eyes are the main source of information, but the main eyes of spiders are ocelli that can form images and, in a few cases, can swivel to ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,556 | The evolutionary ancestry of arthropods dates back to the Cambrian period. The group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians (or their constituent clades) in a superphylum Ecdysozoa. Overall, however, the basal relationships of animals are not ye... | https://en.wikipedia.org/wiki?curid=19827221 |
14,557 | The word "arthropod" comes from the Greek "árthron", "joint", and "pous" (gen. "podos (ποδός)"), i.e. "foot" or "leg", which together mean "jointed leg". The designation "Arthropoda" was coined in 1848 by the German physiologist and zoologist Karl Theodor Ernst von Siebold (1804–1885). | https://en.wikipedia.org/wiki?curid=19827221 |
14,558 | In common parlance, terrestrial arthropods are often called bugs. The term is also occasionally extended to colloquial names for freshwater or marine crustaceans (e.g. Balmain bug, Moreton Bay bug, mudbug) and used by physicians and bacteriologists for disease-causing germs (e.g. superbugs), but entomologists reserve t... | https://en.wikipedia.org/wiki?curid=19827221 |
14,559 | Arthropods are invertebrates with segmented bodies and jointed limbs. The exoskeleton or cuticles consists of chitin, a polymer of glucosamine. The cuticle of many crustaceans, beetle mites, and millipedes (except for bristly millipedes) is also biomineralized with calcium carbonate. Calcification of the endosternite, ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,560 | Estimates of the number of arthropod species vary between 1,170,000 and 5 to 10 million and account for over 80 percent of all known living animal species. The number of species remains difficult to determine. This is due to the census modeling assumptions projected onto other regions in order to scale up from counts a... | https://en.wikipedia.org/wiki?curid=19827221 |
14,561 | They are important members of marine, freshwater, land and air ecosystems, and are one of only two major animal groups that have adapted to life in dry environments; the other is amniotes, whose living members are reptiles, birds and mammals. One arthropod sub-group, insects, is the most species-rich member of all ecol... | https://en.wikipedia.org/wiki?curid=19827221 |
14,562 | The embryos of all arthropods are segmented, built from a series of repeated modules. The last common ancestor of living arthropods probably consisted of a series of undifferentiated segments, each with a pair of appendages that functioned as limbs. However, all known living and fossil arthropods have grouped segments ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,563 | The three-part appearance of many insect bodies and the two-part appearance of spiders is a result of this grouping; in fact there are no external signs of segmentation in mites. Arthropods also have two body elements that are not part of this serially repeated pattern of segments, an ocular somite at the front, where ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,564 | Originally it seems that each appendage-bearing segment had two separate pairs of appendages: an upper, unsegmented exite and a lower, segmented endopod. These would later fuse into a single pair of biramous appendages united by a basal segment (protopod or basipod), with the upper branch acting as a gill while the low... | https://en.wikipedia.org/wiki?curid=19827221 |
14,565 | The most conspicuous specialization of segments is in the head. The four major groups of arthropods – Chelicerata (sea spiders, horseshoe crabs and arachnids), Myriapoda (symphylan, pauropods, millipedes and centipedes), Crustacea (oligostracans, copepods, malacostracans, branchiopods, hexapods, etc.), and the extinct ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,566 | Working out the evolutionary stages by which all these different combinations could have appeared is so difficult that it has long been known as "the arthropod head problem". In 1960, R. E. Snodgrass even hoped it would not be solved, as he found trying to work out solutions to be fun. | https://en.wikipedia.org/wiki?curid=19827221 |
14,567 | Arthropod exoskeletons are made of cuticle, a non-cellular material secreted by the epidermis. Their cuticles vary in the details of their structure, but generally consist of three main layers: the epicuticle, a thin outer waxy coat that moisture-proofs the other layers and gives them some protection; the exocuticle, w... | https://en.wikipedia.org/wiki?curid=19827221 |
14,568 | The exoskeletons of most aquatic crustaceans are biomineralized with calcium carbonate extracted from the water. Some terrestrial crustaceans have developed means of storing the mineral, since on land they cannot rely on a steady supply of dissolved calcium carbonate. Biomineralization generally affects the exocuticle ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,569 | The cuticle may have setae (bristles) growing from special cells in the epidermis. Setae are as varied in form and function as appendages. For example, they are often used as sensors to detect air or water currents, or contact with objects; aquatic arthropods use feather-like setae to increase the surface area of swimm... | https://en.wikipedia.org/wiki?curid=19827221 |
14,570 | Although all arthropods use muscles attached to the inside of the exoskeleton to flex their limbs, some still use hydraulic pressure to extend them, a system inherited from their pre-arthropod ancestors; for example, all spiders extend their legs hydraulically and can generate pressures up to eight times their resting ... | https://en.wikipedia.org/wiki?curid=19827221 |
14,571 | The exoskeleton cannot stretch and thus restricts growth. Arthropods, therefore, replace their exoskeletons by undergoing ecdysis (moulting), or shedding the old exoskeleton after growing a new one that is not yet hardened. Moulting cycles run nearly continuously until an arthropod reaches full size. | https://en.wikipedia.org/wiki?curid=19827221 |
14,572 | The developmental stages between each moult (ecdysis) until sexual maturity is reached is called an instar. Differences between instars can often be seen in altered body proportions, colors, patterns, changes in the number of body segments or head width. After moulting, i.e. shedding their exoskeleton, the juvenile art... | https://en.wikipedia.org/wiki?curid=19827221 |
14,573 | In the initial phase of moulting, the animal stops feeding and its epidermis releases moulting fluid, a mixture of enzymes that digests the endocuticle and thus detaches the old cuticle. This phase begins when the epidermis has secreted a new epicuticle to protect it from the enzymes, and the epidermis secretes the new... | https://en.wikipedia.org/wiki?curid=19827221 |
14,574 | Because arthropods are unprotected and nearly immobilized until the new cuticle has hardened, they are in danger both of being trapped in the old cuticle and of being attacked by predators. Moulting may be responsible for 80 to 90% of all arthropod deaths. | https://en.wikipedia.org/wiki?curid=19827221 |
14,575 | Arthropod bodies are also segmented internally, and the nervous, muscular, circulatory, and excretory systems have repeated components. Arthropods come from a lineage of animals that have a coelom, a membrane-lined cavity between the gut and the body wall that accommodates the internal organs. The strong, segmented lim... | https://en.wikipedia.org/wiki?curid=19827221 |
14,576 | Arthropods have open circulatory systems, although most have a few short, open-ended arteries. In chelicerates and crustaceans, the blood carries oxygen to the tissues, while hexapods use a separate system of tracheae. Many crustaceans, but few chelicerates and tracheates, use respiratory pigments to assist oxygen tran... | https://en.wikipedia.org/wiki?curid=19827221 |
14,577 | The heart is typically a muscular tube that runs just under the back and for most of the length of the hemocoel. It contracts in ripples that run from rear to front, pushing blood forwards. Sections not being squeezed by the heart muscle are expanded either by elastic ligaments or by small muscles, in either case conne... | https://en.wikipedia.org/wiki?curid=19827221 |
14,578 | Arthropods have a wide variety of respiratory systems. Small species often do not have any, since their high ratio of surface area to volume enables simple diffusion through the body surface to supply enough oxygen. Crustacea usually have gills that are modified appendages. Many arachnids have book lungs. Tracheae, sys... | https://en.wikipedia.org/wiki?curid=19827221 |
14,579 | Living arthropods have paired main nerve cords running along their bodies below the gut, and in each segment the cords form a pair of ganglia from which sensory and motor nerves run to other parts of the segment. Although the pairs of ganglia in each segment often appear physically fused, they are connected by commissu... | https://en.wikipedia.org/wiki?curid=19827221 |
14,580 | There are two different types of arthropod excretory systems. In aquatic arthropods, the end-product of biochemical reactions that metabolise nitrogen is ammonia, which is so toxic that it needs to be diluted as much as possible with water. The ammonia is then eliminated via any permeable membrane, mainly through the g... | https://en.wikipedia.org/wiki?curid=19827221 |
14,581 | The stiff cuticles of arthropods would block out information about the outside world, except that they are penetrated by many sensors or connections from sensors to the nervous system. In fact, arthropods have modified their cuticles into elaborate arrays of sensors. Various touch sensors, mostly setae, respond to diff... | https://en.wikipedia.org/wiki?curid=19827221 |
14,582 | Most arthropods lack balance and acceleration sensors, and rely on their eyes to tell them which way is up. The self-righting behavior of cockroaches is triggered when pressure sensors on the underside of the feet report no pressure. However, many malacostracan crustaceans have statocysts, which provide the same sort o... | https://en.wikipedia.org/wiki?curid=19827221 |
14,583 | The proprioceptors of arthropods, sensors that report the force exerted by muscles and the degree of bending in the body and joints, are well understood. However, little is known about what other internal sensors arthropods may have. | https://en.wikipedia.org/wiki?curid=19827221 |
14,584 | Most arthropods have sophisticated visual systems that include one or more usually both of compound eyes and pigment-cup ocelli ("little eyes"). In most cases ocelli are only capable of detecting the direction from which light is coming, using the shadow cast by the walls of the cup. However, the main eyes of spiders a... | https://en.wikipedia.org/wiki?curid=19827221 |
14,585 | Compound eyes consist of fifteen to several thousand independent ommatidia, columns that are usually hexagonal in cross section. Each ommatidium is an independent sensor, with its own light-sensitive cells and often with its own lens and cornea. Compound eyes have a wide field of view, and can detect fast movement and,... | https://en.wikipedia.org/wiki?curid=19827221 |
14,586 | A few arthropods, such as barnacles, are hermaphroditic, that is, each can have the organs of both sexes. However, individuals of most species remain of one sex their entire lives. A few species of insects and crustaceans can reproduce by parthenogenesis, especially if conditions favor a "population explosion". However... | https://en.wikipedia.org/wiki?curid=19827221 |
14,587 | Aquatic arthropods may breed by external fertilization, as for example horseshoe crabs do, or by internal fertilization, where the ova remain in the female's body and the sperm must somehow be inserted. All known terrestrial arthropods use internal fertilization. Opiliones (harvestmen), millipedes, and some crustaceans... | https://en.wikipedia.org/wiki?curid=19827221 |
14,588 | Most arthropods lay eggs, but scorpions are ovoviparous: they produce live young after the eggs have hatched inside the mother, and are noted for prolonged maternal care. Newly born arthropods have diverse forms, and insects alone cover the range of extremes. Some hatch as apparently miniature adults (direct developmen... | https://en.wikipedia.org/wiki?curid=19827221 |
14,589 | Based on the distribution of shared plesiomorphic features in extant and fossil taxa, the last common ancestor of all arthropods is inferred to have been as a modular organism with each module covered by its own sclerite (armor plate) and bearing a pair of biramous limbs. However, whether the ancestral limb was uniramo... | https://en.wikipedia.org/wiki?curid=19827221 |
14,590 | This Ur-arthropod had a ventral mouth, pre-oral antennae and dorsal eyes at the front of the body. It was assumed to have been a non-discriminatory sediment feeder, processing whatever sediment came its way for food, but fossil findings hint that the last common ancestor of both arthropods and priapulida shared the sam... | https://en.wikipedia.org/wiki?curid=19827221 |
14,591 | It has been proposed that the Ediacaran animals "Parvancorina" and "Spriggina", from around , were arthropods, but later study shows that their affinities of being origin of arthropods are not reliable. Small arthropods with bivalve-like shells have been found in Early Cambrian fossil beds dating in China and Australia... | https://en.wikipedia.org/wiki?curid=19827221 |
14,592 | The earliest fossil crustaceans date from about in the Cambrian, and fossil shrimp from about apparently formed a tight-knit procession across the seabed. Crustacean fossils are common from the Ordovician period onwards. They have remained almost entirely aquatic, possibly because they never developed excretory systems... | https://en.wikipedia.org/wiki?curid=19827221 |
14,593 | Arthropods provide the earliest identifiable fossils of land animals, from about in the Late Silurian, and terrestrial tracks from about appear to have been made by arthropods. Arthropods possessed attributes that were easy coopted for life on land; their existing jointed exoskeletons provided protection against desicc... | https://en.wikipedia.org/wiki?curid=19827221 |
14,594 | The oldest known arachnid is the trigonotarbid "Palaeotarbus jerami", from about in the Silurian period. "Attercopus fimbriunguis", from in the Devonian period, bears the earliest known silk-producing spigots, but its lack of spinnerets means it was not one of the true spiders, which first appear in the Late Carbonifer... | https://en.wikipedia.org/wiki?curid=19827221 |
14,595 | The oldest possible insect fossil is the Devonian "Rhyniognatha hirsti", dated at , but its mandibles are of a type found only in winged insects, which suggests that the earliest insects appeared in the Silurian period, although later study shows possibility that "Rhyniognatha" can be myriapod, not an insect. The Mazon... | https://en.wikipedia.org/wiki?curid=19827221 |
14,596 | From 1952 to 1977, zoologist Sidnie Manton and others argued that arthropods are polyphyletic, in other words, that they do not share a common ancestor that was itself an arthropod. Instead, they proposed that three separate groups of "arthropods" evolved separately from common worm-like ancestors: the chelicerates, in... | https://en.wikipedia.org/wiki?curid=19827221 |
14,597 | Further analysis and discoveries in the 1990s reversed this view, and led to acceptance that arthropods are monophyletic, in other words they are inferred to share a common ancestor that was itself an arthropod. For example, Graham Budd's analyses of "Kerygmachela" in 1993 and of "Opabinia" in 1996 convinced him that t... | https://en.wikipedia.org/wiki?curid=19827221 |
14,598 | A contrary view was presented in 2003, when Jan Bergström and Xian-Guang Hou argued that, if arthropods were a "sister-group" to any of the anomalocarids, they must have lost and then re-evolved features that were well-developed in the anomalocarids. The earliest known arthropods ate mud in order to extract food partic... | https://en.wikipedia.org/wiki?curid=19827221 |
14,599 | Higher up the "family tree", the Annelida have traditionally been considered the closest relatives of the Panarthropoda, since both groups have segmented bodies, and the combination of these groups was labelled Articulata. There had been competing proposals that arthropods were closely related to other groups such as n... | https://en.wikipedia.org/wiki?curid=19827221 |
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