document_title: Starfish

question_text: what type of symmetry does a sea star have

question_tokens: what type of symmetry does a sea star have

text: Starfish

text: Taxonomy

text: The scientific name Asteroidea was given to starfish by the French zoologist de Blainville in 1830.[3] It is derived from the Greek aster, ἀστήρ (a star) and the Greek eidos, εἶδος (form, likeness, appearance).[4] The class Asteroidea belongs to the phylum Echinodermata. As well as the starfish, the echinoderms include sea urchins, sand dollars, brittle and basket stars, sea cucumbers and crinoids. The larvae of echinoderms have bilateral symmetry, but during metamorphosis this is replaced with radial symmetry, typically pentameric.[5] Adult echinoderms are characterized by having a water vascular system with external tube feet and a calcareous endoskeleton consisting of ossicles connected by a mesh of collagen fibres.[6] Starfish are included in the subphylum Asterozoa, the characteristics of which include a flattened, star-shaped body as adults consisting of a central disc and multiple radiating arms. The subphylum includes the two classes of Asteroidea, the starfish, and Ophiuroidea, the brittle stars and basket stars. Asteroids have broad-based arms with skeletal support provided by calcareous plates in the body wall[7] while ophiuroids have clearly demarcated slender arms strengthened by paired fused ossicles forming jointed "vertebrae".[8]

text: The starfish are a large and diverse class with about 1,500 living species. There are seven extant orders, Brisingida, Forcipulatida, Notomyotida, Paxillosida, Spinulosida, Valvatida and Velatida[1] and two extinct ones, Calliasterellidae and Trichasteropsida.[2]

text: Anatomy

text: Most starfish have five arms that radiate from a central disc, but the number varies with the group. Luidia ciliaris has seven arms, members of the Solasteridae have ten to fifteen while the Antarctic Labidiaster annulatus can have up to fifty. It is not unusual in species that typically have five arms for some individuals to possess six or more through abnormal development.[9]

text: Body wall

text: The body wall consists of a thin cuticle, an epidermis consisting of a single layer of cells, a thick dermis formed of connective tissue and a thin coelomic myoepithelial layer, which provides the longitudinal and circular musculature. The dermis contains an endoskeleton of calcium carbonate components known as ossicles. These are honeycombed structures composed of calcite microcrystals arranged in a lattice.[10] They vary in form, with some bearing external granules, tubercles and spines, but most are tabular plates that fit neatly together in a tessellated manner and form the main covering of the aboral surface.[11] Some are specialised structures such as the madreporite (the entrance to the water vascular system), pedicellariae and paxillae.[10] Pedicellariae are compound ossicles with forceps-like jaws. They remove debris from the body surface and wave around on flexible stalks in response to physical or chemical stimuli while continually making biting movements. They often form clusters surrounding spines.[12][13] Paxillae are umbrella-like structures found on starfish that live buried in sediment. The edges of adjacent paxillae meet to form a false cuticle with a water cavity beneath in which the madreporite and delicate gill structures are protected. All the ossicles, including those projecting externally, are covered by the epidermal layer.[10]

text: Several groups of starfish, including Valvatida and Forcipulatida, possess pedicellariae.[12] In Forcipulatida, such as Asterias and Pisaster, they occur in pompom-like tufts at the base of each spine, whereas in the Goniasteridae, such as Hippasteria phrygiana, the pedicellariae are scattered over the body surface. Some are thought to assist in defence, while others aid in feeding or in the removal of organisms attempting to settle on the starfish's surface.[14] Some species like Labidiaster annulatus, Rathbunaster californicus and Novodinia antillensis use their large pedicellariae to capture small fish and crustaceans.[15]

text: There may also be papulae, thin-walled protrusions of the body cavity that reach through the body wall and extend into the surrounding water. These serve a respiratory function.[5] The structures are supported by collagen fibres set at right angles to each other and arranged in a three-dimensional web with the ossicles and papulae in the interstices. This arrangement enables both easy flexion of the arms by the starfish and the rapid onset of stiffness and rigidity required for actions performed under stress.[16]

text: Water vascular system

text: The water vascular system of the starfish is a hydraulic system made up of a network of fluid-filled canals and is concerned with locomotion, adhesion, food manipulation and gas exchange. Water enters the system through the madreporite, a porous, often conspicuous, sieve-like ossicle on the aboral surface. It is linked through a stone canal, often lined with calcareous material, to a ring canal around the mouth opening. A set of radial canals leads off this; one radial canal runs along the ambulacral groove in each arm. There are short lateral canals branching off alternately to either side of the radial canal, each ending in an ampulla. These bulb-shaped organs are joined to tube feet (podia) on the exterior of the animal by short linking canals that pass through ossicles in the ambulacral groove. There are usually two rows of tube feet but in some species, the lateral canals are alternately long and short and there appear to be four rows. The interior of the whole canal system is lined with cilia.[17]

text: When longitudinal muscles in the ampullae contract, valves in the lateral canals close and water is forced into the tube feet. These extend to contact the substrate. Although the tube feet resemble suction cups in appearance, the gripping action is a function of adhesive chemicals rather than suction.[18] Other chemicals and relaxation of the ampullae allow for release from the substrate. The tube feet latch on to surfaces and move in a wave, with one arm section attaching to the surface as another releases.[19][20] Some multi-armed, fast-moving starfish such as the sunflower seastar (Pycnopodia helianthoides) pull themselves along with some of their arms while letting others trail behind. Other starfish turn up the tips of their arms while moving which gives maximum exposure of the sensory tube feet and the eyespot to external stimuli.[21]

text: Most starfish cannot move quickly, a typical speed being that of the leather star (Dermasterias imbricata), which can manage just 15 cm (6 in) in a minute.[22] Some burrowing species from the genera Astropecten and Luidia have points rather than suckers on their long tube feet and are capable of much more rapid motion, "gliding" across the ocean floor. The sand star (Luidia foliolata) can travel at a speed of 2.8 m (9 ft 2 in) per minute.[23]

text: Apart from their function in locomotion, the tube feet act as accessory gills. The water vascular system serves to transport oxygen from, and carbon dioxide to, the tube feet and also nutrients from the gut to the muscles involved in locomotion. Fluid movement is bidirectional and initiated by cilia.[17] Gas exchange also takes place through other gills known as papulae, which are thin-walled bulges on the aboral surface of the disc and arms. Oxygen is transferred from these to the coelomic fluid, which acts as the transport medium for gasses. Oxygen dissolved in the water is distributed through the body mainly by the fluid in the main body cavity; the circulatory system may also play a minor role.[24]

text: Digestive system and excretion

text: The gut of a starfish occupies most of the disc and extends into the arms. The mouth is located in the centre of the oral surface, where it is surrounded by a tough peristomial membrane and closed with a sphincter. The mouth opens through a short oesophagus into a stomach divided by a constriction into a larger, eversible cardiac portion and a smaller pyloric portion. The cardiac stomach is glandular and pouched, and is supported by ligaments attached to ossicles in the arms so it can be pulled back into position after it has been everted. The pyloric stomach has two extensions into each arm: the pyloric caeca. These are elongated, branched hollow tubes that are lined by a series of glands, which secrete digestive enzymes and absorb nutrients from the food. A short intestine and rectum run from the pyloric stomach to open at a small anus at the apex of the aboral surface of the disc.[25]

text: Primitive starfish, such as Astropecten and Luidia, swallow their prey whole, and start to digest it in their cardiac stomachs. Shell valves and other inedible materials are ejected through their mouths. The semi-digested fluid is passed into their pyloric stomachs and caeca where digestion continues and absorption ensues.[25] In more advanced species of starfish, the cardiac stomach can be everted from the organism's body to engulf and digest food. When the prey is a clam or other bivalve, the starfish pulls with its tube feet to separate the two valves slightly, and inserts a small section of its stomach, which releases enzymes to digest the prey. The stomach and the partially digested prey are later retracted into the disc. Here the food is passed on to the pyloric stomach, which always remains inside the disc.[26] The retraction and contraction of the cardiac stomach is activated by a neuropeptide known as NGFFYamide.[27]

text: Because of this ability to digest food outside the body, starfish can hunt prey much larger than their mouths. Their diets include clams and oysters, arthropods, small fish and gastropod molluscs. Some starfish are not pure carnivores, supplementing their diets with algae or organic detritus. Some of these species are grazers, but others trap food particles from the water in sticky mucus strands that are swept towards the mouth along ciliated grooves.[25]

text: The main nitrogenous waste product is ammonia. Starfish have no distinct excretory organs; waste ammonia is removed by diffusion through the tube feet and papulae.[24] The body fluid contains phagocytic cells, coelomocytes, which are also found within the hemal and water vascular systems. These cells engulf waste material, and eventually migrate to the tips of the papulae, where a portion of body wall is nipped off and ejected into the surrounding water. Some waste may also be excreted by the pyloric glands and voided with the faeces.[24]

text: Starfish do not appear to have any mechanisms for osmoregulation, and keep their body fluids at the same salt concentration as the surrounding water. Although some species can tolerate relatively low salinity, the lack of an osmoregulation system probably explains why starfish are not found in fresh water or even in many estuarine environments.[24]

text: Sensory and nervous systems

text: Although starfish do not have many well-defined sense organs, they are sensitive to touch, light, temperature, orientation and the status of the water around them. The tube feet, spines and pedicellariae are sensitive to touch. The tube feet, especially those at the tips of the rays, are also sensitive to chemicals, enabling the starfish to detect odour sources such as food.[26] There are eyespots at the ends of the arms, each one made of 80–200 simple ocelli. These are composed of pigmented epithelial cells that respond to light and are covered by a thick, transparent cuticle that both protects the ocelli and acts to focus light. Many starfish also possess individual photoreceptor cells in other parts of their bodies and respond to light even when their eyespots are covered. Whether they advance or retreat depends on the species.[28]

text: While a starfish lacks a centralized brain, it has a complex nervous system with a nerve ring around the mouth and a radial nerve running along the ambulacral region of each arm parallel to the radial canal. The peripheral nerve system consists of two nerve nets: a sensory system in the epidermis and a motor system in the lining of the coelomic cavity. Neurons passing through the dermis connect the two.[28] The ring nerves and radial nerves have sensory and motor components and coordinate the starfish's balance and directional systems.[5] The sensory component receives input from the sensory organs while the motor nerves control the tube feet and musculature. The starfish does not have the capacity to plan its actions. If one arm detects an attractive odour, it becomes dominant and temporarily over-rides the other arms to initiate movement towards the prey. The mechanism for this is not fully understood.[28]

text: Circulatory system

text: The body cavity contains the circulatory or haemal system. The vessels form three rings: one around the mouth (the hyponeural haemal ring), another around the digestive system (the gastric ring) and the third near the aboral surface (the genital ring). The heart beats about six times a minute and is at the apex of a vertical channel (the axial vessel) that connects the three rings. At the base of each arm are paired gonads; a lateral vessel extends from the genital ring past the gonads to the tip of the arm. This vessel has a blind end and there is no continuous circulation of the fluid within it. This liquid does not contain a pigment and has little or no respiratory function but is probably used to transport nutrients around the body.[29]

text: Secondary metabolites

text: Starfish produce a large number of secondary metabolites in the form of lipids, including steroidal derivatives of cholesterol, and fatty acid amides of sphingosine. The steroids are mostly saponins, known as asterosaponins, and their sulphated derivatives. They vary between species and are typically formed from up to six sugar molecules (usually glucose and galactose) connected by up to three glycosidic chains. Long-chain fatty acid amides of sphingosine occur frequently and some of them have known pharmacological activity. Various ceramides are also known from starfish and a small number of alkaloids have also been identified. The functions of these chemicals in the starfish have not been fully investigated but most have roles in defence and communication. Some are feeding deterrents used by the starfish to discourage predation. Others are antifoulants and supplement the pedicellariae to prevent other organisms from settling on the starfish's aboral surface. Some are alarm pheromones and escape-eliciting chemicals, the release of which trigger responses in conspecific starfish but often produce escape responses in potential prey.[30] Research into the efficacy of these compounds for possible pharmacological or industrial use occurs worldwide.[31]

text: Life cycle

text: Sexual reproduction

text: Most species of starfish are gonochorous, there being separate male and female individuals. These are usually not distinguishable externally as the gonads cannot be seen, but their sex is apparent when they spawn. Some species are simultaneous hermaphrodites, producing eggs and sperm at the same time and in a few of these, the same gonad, called an ovotestis, produces both eggs and sperm.[32] Other starfish are sequential hermaphrodites. Protandrous individuals of species like Asterina gibbosa start life as males before changing sex into females as they grow older. In some species such as Nepanthia belcheri, a large female can split in half and the resulting offspring are males. When these grow large enough they change back into females.[33]

text: Each starfish arm contains two gonads that release gametes through openings called gonoducts, located on the central disc between the arms. Fertilization is generally external but in a few species, internal fertilization takes place. In most species, the buoyant eggs and sperm are simply released into the water (free spawning) and the resulting embryos and larvae live as part of the plankton. In others, the eggs may be stuck to the undersides of rocks.[34] In certain species of starfish, the females brood their eggs – either by simply enveloping them[34] or by holding them in specialised structures. Brooding may be done in pockets on the starfish's aboral surface,[35][36] inside the pyloric stomach (Leptasterias tenera)[37] or even in the interior of the gonads themselves.[32] Those starfish that brood their eggs by "sitting" on them usually assume a humped posture with their discs raised off the substrate.[38] Pteraster militaris broods a few of its young and disperses the remaining eggs, that are too numerous to fit into its pouch.[35] In these brooding species, the eggs are relatively large, and supplied with yolk, and they generally develop directly into miniature starfish without an intervening larval stage.[32] The developing young are called lecithotrophic because they obtain their nutrition from the yolk as opposed to "planktotrophic" larvae that feed in the water column. In Parvulastra parvivipara, an intragonadal brooder, the young starfish obtain nutrients by eating other eggs and embryos in the brood pouch.[39] Brooding is especially common in polar and deep-sea species that live in environments unfavourable for larval development[36] and in smaller species that produce just a few eggs.[40][41]

text: In the tropics, a plentiful supply of phytoplankton is continuously available for starfish larvae to feed on. Spawning takes place at any time of year, each species having its own characteristic breeding season.[42] In temperate regions, the spring and summer brings an increase in food supplies. The first individual of a species to spawn may release a pheromone that serves to attract other starfish to aggregate and to release their gametes synchronously.[43] In other species, a male and female may come together and form a pair.[44][45] This behaviour is called pseudocopulation[46] and the male climbs on top, placing his arms between those of the female. When she releases eggs into the water, he is induced to spawn.[43] Starfish may use environmental signals to coordinate the time of spawning (day length to indicate the correct time of the year,[44] dawn or dusk to indicate the correct time of day), and chemical signals to indicate their readiness to breed. In some species, mature females produce chemicals to attract sperm in the sea water.[47]

text: Larval development

text: Most starfish embryos hatch at the blastula stage. The original ball of cells develops a lateral pouch, the archenteron. The entrance to this is known as the blastopore and it will later develop into the anus. Another invagination of the surface will fuse with the tip of the archenteron as the mouth while the interior section will become the gut. At the same time, a band of cilia develops on the exterior. This enlarges and extends around the surface and eventually onto two developing arm-like outgrowths. At this stage the larva is known as a bipinnaria. The cilia are used for locomotion and feeding, their rhythmic beat wafting phytoplankton towards the mouth.[12]

text: The next stage in development is a brachiolaria larva and involves the growth of three short, additional arms. These are at the anterior end, surround a sucker and have adhesive cells at their tips. Both bipinnaria and brachiolaria larvae are bilaterally symmetrical. When fully developed, the brachiolaria settles on the seabed and attaches itself with a short stalk formed from the ventral arms and sucker. Metamorphosis now takes place with a radical rearrangement of tissues. The left side of the larval body becomes the oral surface of the juvenile and the right side the aboral surface. Part of the gut is retained but the mouth and anus move to new positions. Some of the body cavities degenerate but others become the water vascular system and the visceral coelom. The starfish is now pentaradially symmetrical. It casts off its stalk and becomes a free-living juvenile starfish about 1 mm (0.04 in) in diameter. Starfish of the order Paxillosida have no brachiolaria stage, with the bipinnaria larvae settling on the seabed and developing directly into juveniles.[12]

text: Asexual reproduction

text: Some species of starfish are able to reproduce asexually as adults either by fission of their central discs[48] or by autotomy of one or more of their arms. Which of these processes occurs depends on the genus. Among starfish that are able to regenerate their whole body from a single arm, some can do so even from fragments just 1 cm (0.4 in) long.[49] Single arms that regenerate a whole individual are called comet forms. The division of the starfish, either across its disc or at the base of the arm, is usually accompanied by a weakness in the structure that provides a fracture zone.[50]

text: The larvae of several species of starfish can reproduce asexually before they reach maturity.[51] They do this by autotomising some parts of their bodies or by budding.[52] When such a larva senses that food is plentiful, it takes the path of asexual reproduction rather than normal development.[53] Though this costs it time and energy and delays maturity, it allows a single larva to give rise to multiple adults when the conditions are appropriate.[52]

text: Regeneration

text: Some species of starfish have the ability to regenerate lost arms and can regrow an entire new limb given time.[49] A few can regrow a complete new disc from a single arm, while others need at least part of the central disc to be attached to the detached part.[24] Regrowth can take several months or years,[49] and starfish are vulnerable to infections during the early stages after the loss of an arm. A separated limb lives off stored nutrients until it regrows a disc and mouth and is able to feed again.[49] Other than fragmentation carried out for the purpose of reproduction, the division of the body may happen inadvertently due to part being detached by a predator, or part may be actively shed by the starfish in an escape response.[24] The loss of parts of the body is achieved by the rapid softening of a special type of connective tissue in response to nervous signals. This type of tissue is called catch connective tissue and is found in most echinoderms.[54] An autotomy-promoting factor has been identified which, when injected into another starfish, causes rapid shedding of arms.[55]

text: Lifespan

text: The lifespan of a starfish varies considerably between species, generally being longer in larger forms and in those with planktonic larvae. For example, Leptasterias hexactis broods a small number of large-yolked eggs. It has an adult weight of 20 g (0.7 oz), reaches sexual maturity in two years and lives for about ten years.[12] Pisaster ochraceus releases a large number of eggs into the sea each year and has an adult weight of 80 g (2.8 oz). It reaches maturity in five years and has a maximum recorded lifespan of 34 years.[12]

text: Ecology

text: Distribution and habitat

text: Echinoderms, including starfish, maintain a delicate internal electrolyte balance that is in equilibrium with sea water. This means that it is only possible for them to live in a marine environment and they are not found in any freshwater habitats.[19] Starfish species inhabit all of the world's oceans. Habitats range from tropical coral reefs, rocky shores, tidal pools, mud, and sand to kelp forests, seagrass meadows[56] and the deep-sea floor down to at least 6,000 m (20,000 ft).[57] The greatest diversity of species occurs in coastal areas.[56]

text: Diet

text: Most species are generalist predators, eating microalgae, sponges, bivalves, snails and other small animals.[26][58] The crown-of-thorns starfish consumes coral polyps,[59] while other species are detritivores, feeding on decomposing organic material and faecal matter.[58][60] A few are suspension feeders, gathering in phytoplankton; Henricia and Echinaster often occur in association with sponges, benefiting from the water current they produce.[61] Various species have been shown to be able to absorb organic nutrients from the surrounding water, and this may form a significant portion of their diet.[61]

text: The processes of feeding and capture may be aided by special parts; Pisaster brevispinus, the short-spined pisaster from the West Coast of America, can use a set of specialized tube feet to dig itself deep into the soft substrate to extract prey (usually clams).[62] Grasping the shellfish, the starfish slowly pries open the prey's shell by wearing out its adductor muscle, and then inserts its everted stomach into the crack to digest the soft tissues. The gap between the valves need only be a fraction of a millimetre wide for the stomach to gain entry.[19]

text: Ecological impact

text: Starfish are keystone species in their respective marine communities. Their relatively large sizes, diverse diets and ability to adapt to different environments makes them ecologically important.[63] The term "keystone species" was in fact first used by Robert Paine in 1966 to describe a starfish, Pisaster ochraceus.[64] When studying the low intertidal coasts of Washington state, Paine found that predation by P. ochraceus was a major factor in the diversity of species. Experimental removals of this top predator from a stretch of shoreline resulted in lower species diversity and the eventual domination of Mytilus mussels, which were able to outcompete other organisms for space and resources.[65] Similar results were found in a 1971 study of Stichaster australis on the intertidal coast of the South Island of New Zealand. S. australis was found to have removed most of a batch of transplanted mussels within two or three months of their placement, while in an area from which S. australis had been removed, the mussels increased in number dramatically, overwhelming the area and threatening biodiversity.[66]

text: The feeding activity of the omnivorous starfish Oreaster reticulatus on sandy and seagrass bottoms in the Virgin Islands appears to regulate the diversity, distribution and abundance of microorganisms. These starfish engulf piles of sediment removing the surface films and algae adhering to the particles.[67] Organisms that dislike this disturbance are replaced by others better able to rapidly recolonise "clean" sediment. In addition, foraging by these migratory starfish creates diverse patches of organic matter, which may play a role in the distribution and abundance of organisms such as fish, crabs and sea urchins that feed on the sediment.[68]

text: Starfish sometimes have negative effects on ecosystems. Outbreaks of crown-of-thorns starfish have caused damage to coral reefs in Northeast Australia and French Polynesia.[59][69] A study in Polynesia found that coral cover declined drastically with the arrival of migratory starfish in 2006, dropping from 50% to under 5% in three years. This had an unintended effect on reef-feeding fish and the whole benthic community.[59] Asterias amurensis is one of a few echinoderm invasive species. Its larvae likely arrived in Tasmania from central Japan via water discharged from ships in the 1980s. The species has since grown in numbers to the point where they threaten commercially important bivalve populations. As such, they are considered pests,[70] and are on the Invasive Species Specialist Group's list of the world's 100 worst invasive species.[71]

text: Threats

text: Starfish may be preyed on by conspecifics, other starfish species, tritons, crabs, fish, gulls and sea otters.[40][70][72][73] Their first lines of defence are the saponins present in their body walls, which have unpleasant flavours.[74] Some starfish such as Astropecten polyacanthus also include powerful toxins such as tetrodotoxin among their chemical armoury, and the slime star can ooze out large quantities of repellent mucus. They also have body armour in the form of hard plates and spines.[75] The crown-of-thorns starfish is particularly unattractive to potential predators, being heavily defended by sharp spines, laced with toxins and sometimes with bright warning colours.[76] Other species protect their vulnerable tube feet and arm tips by lining their ambulacral grooves with spines and heavily plating their extremities.[75]

text: Several species sometimes suffer from a wasting condition caused by bacteria in the genus Vibrio;[72] however, a more widespread wasting disease, causing mass mortalities among starfish, appears sporadically. A paper published in November 2014 revealed the most likely cause of this disease to be a densovirus the authors named sea star-associated densovirus (SSaDV).[77] The protozoan Orchitophrya stellarum is known to infect the gonads of starfish and damage tissue.[72] Starfish are vulnerable to high temperatures. Experiments have shown that the feeding and growth rates of P. ochraceus reduce greatly when their body temperatures rise above 23 °C (73 °F) and that they die when their temperature rises to 30 °C (86 °F).[78][79] This species has a unique ability to absorb seawater to keep itself cool when it is exposed to sunlight by a receding tide.[80] It also appears to rely on its arms to absorb heat, so as to protect the central disc and vital organs like the stomach.[81]

text: Starfish and other echinoderms are sensitive to marine pollution.[82] The common starfish is considered to be a bioindicator for marine ecosystems.[83] A 2009 study found that P. ochraceus is unlikely to be affected by ocean acidification as severely as other marine animals with calcareous skeletons. In other groups, structures made of calcium carbonate are vulnerable to dissolution when the pH is lowered. Researchers found that when P. ochraceus were exposed to 21 °C (70 °F) and 770 ppm carbon dioxide (beyond rises expected in the next century), they were relatively unaffected. Their survival is likely due to the nodular nature of their skeletons, which are able to compensate for a shortage of carbonate by growing more fleshy tissue.[84]

text: Evolutionary history

text: Echinoderms first appeared in the fossil record in the Cambrian. The first known asterozoans were the Somasteroidea, which exhibit characteristics of both groups. Modern starfish and brittle stars probably had a common somasteroid ancestor.[85] Starfish are infrequently found as fossils, possibly because their hard skeletal components separate as the animal decays. However, although starfish fossils are uncommon, there are a few places where accumulations of complete skeletal structures occur, fossilized in place in Lagerstätten — so-called "starfish beds".[86]

text: By the late Paleozoic, the crinoids and blastoids were the predominant echinoderms, and some limestones from this period are made almost entirely from fragments from these groups. In the two major extinction events that occurred during the late Devonian and late Permian, the blastoids were wiped out and only a few species of crinoids survived.[85] Many starfish species also became extinct in these events, but afterwards the surviving few species diversified rapidly within about sixty million years during the Early Jurassic and the beginning of the Middle Jurassic.[7][87] A 2012 study found that speciation in starfish can occur rapidly. During the last 6,000 years, divergence in the larval development of Cryptasterina hystera and Cryptasterina pentagona has taken place, the former adopting internal fertilization and brooding and the latter remaining a broadcast spawner.[88]

text: Diversity

text: Living asteroids, the Neoasteroidea, are morphologically distinct from their forerunners in the Paleozoic. The taxonomy of the group is relatively stable but there is ongoing debate about the status of the Paxillosida, and the deep-water sea daisies, though clearly Asteroidea and currently included in Velatida, do not fit easily in any accepted lineage. Phylogenetic data suggests that they may be a sister group, the Concentricycloidea, to the Neoasteroidea, or that the Velatida themselves may be a sister group.[87]

text: Living groups

text: Brisingida (2 families, 17 genera, 111 species) [89]

text: Forcipulatida (6 families, 63 genera, 269 species) [93]

text: Notomyotida (1 family, 8 genera, 75 species) [96]

text: Paxillosida (7 families, 48 genera, 372 species) [97]

text: Spinulosida (1 family, 8 genera, 121 species) [100]

text: Valvatida (16 families, 172 genera, 695 species) [104]

text: Velatida (4 families, 16 genera, 138 species) [108]

text: Extinct groups

text: Extinct groups within the Asteroidea include:[2]

text:
† Calliasterellidae, with the type genus Calliasterella from the Devonian periods and Carboniferous.[111]
† Trichasteropsida, with the Triassic genus Trichasteropsis (at least 2 species).[2]

text: Phylogeny

text: The phylogeny of the Asteroidea has been difficult to resolve, with visible (morphological) features proving inadequate, and the question of whether traditional taxa are clades in doubt.[2] The phylogeny proposed by Gale in 1987 is:[2][112]

text:
† Palaeozoic Asteroids

Paxillosida

Valvatida, including Velatida, Spinulosida (not a clade)[2]

Forcipulatida, including Brisingida

text: The phylogeny proposed by Blake in 1987 is:[2][113]

text:
† Palaeozoic Asteroids

† Calliasterellidae

† Compasteridae

† Trichasteropsida

Brisingida

Forcipulatida

Spinulosida

Velatida

Notomyotida

Valvatida

Paxillosida

text: Later work making use of molecular evidence, with or without the use of morphological evidence, had by 2000 failed to resolve the argument.[2] In 2011, on further molecular evidence, Janies and colleagues noted that the phylogeny of the echinoderms "has proven difficult", and that "the overall phylogeny of extant echinoderms remains sensitive to the choice of analytical methods". They presented a phylogenetic tree for the living Asteroidea only; using the traditional names of starfish orders where possible, and indicating "part of" otherwise, the phylogeny is shown below. The Solasteridae are split from the Velatida, and the old Spinulosida is broken up.[114]

text:
Solasteridae and part of Spinulosida, e.g. Stegnaster and part of Valvatida, e.g. Asterina

Odontasteridae, which was a part of Valvatida

Paxillosida

part of Spinulosida, e.g. Echinaster, part of Valvatida, e.g. Archaster

Forcipulatida

Brisingida with part of Velatida, e.g. Caymanostella and part of Forcipulatida, e.g. Stichaster

Velatida except for Solasteridae

text: Notomyotida (not analysed)

text: Human relations

text: In research

text: Starfish are deuterostomes, closely related, together with all other echinoderms, to chordates, and are used in reproductive and developmental studies. Female starfishs produce large numbers of oocytes that are easily isolated; these can be stored in a pre-meiosis phase and stimulated to complete division by the use of 1-methyladenine.[115] Starfish oocytes are well suited for this research as they are large and easy to handle, transparent, simple to maintain in sea water at room temperature, and they develop rapidly.[116] Asterina pectinifera, used as a model organism for this purpose, is resilient and easy to breed and maintain in the laboratory.[117]

text: Another area of research is the ability of starfish to regenerate lost body parts. The stem cells of adult humans are incapable of much differentiation and understanding the regrowth, repair and cloning processes in starfish may have implications for human medicine.[118]

text: Starfish also have an unusual ability to expel foreign objects from their bodies, which makes them difficult to tag for research tracking purposes.[119]

text: In legend and culture

text: An aboriginal Australian fable retold by the Welsh school headmaster William Jenkyn Thomas (1870–1959)[120] tells how some animals needed a canoe to cross the ocean. Whale had one but refused to lend it, so Starfish kept him busy, telling him stories and grooming him to remove parasites, while the others stole the canoe. When Whale realized the trick he beat Starfish ragged, which is how Starfish still is today.[121]

text: In 1900, the scholar Edward Tregear documented The Creation Song, which he describes as "an ancient prayer for the dedication of a high chief" of Hawaii. Among the "uncreated gods" described early in the song are the male Kumilipo ("Creation") and the female Poele, both born in the night, a coral insect, the earthworm, and the starfish.[122]

text: Georg Eberhard Rumpf's 1705 The Ambonese Curiosity Cabinet describes the tropical varieties of Stella Marina or Bintang Laut, "Sea Star", in Latin and Malay respectively, known in the waters around Ambon. He writes that the Histoire des Antilles reports that when the sea stars "see thunder storms approaching, [they] grab hold of many small stones with their little legs, looking to ... hold themselves down as if with anchors".[123]

text: Starfish is the title of novels by Peter Watts[124] and Jennie Orbell,[125] and in 2012, Alice Addison wrote a non-fiction book subtitled "A year in the life of bereavement and depression".[126] The Starfish and the Spider is a 2006 business management book by Ori Brafman and Rod Beckstrom; its title alludes to the ability of the starfish to regenerate itself because of its decentralized nervous system, and the book suggests ways that a decentralized organisation may flourish.[127]

text: In his 2002 book The Divine Mystery Fort, Sri Sai Kaleshwar Swami wrote, "An eighth type of supernatural power object is a starfish. Sometimes at the full moon time, when the moon is really dazzling and hitting on the ocean, a starfish jumps out of the water and falls down. If you can get that you can suck unbelievable cosmic energy. You can use it as your own power object. It has to be only on the full moon day when it comes up."

text: In the Nickelodeon animated television series SpongeBob SquarePants, the eponymous character's best friend is a dim-witted starfish, Patrick Star.[128]

text: As food

text: Starfish are widespread in the oceans, but are only occasionally used as food. There may be good reason for this: the bodies of numerous species are dominated by bony ossicles, and the body wall of many species contains saponins, which have an unpleasant taste,[74] and others contain tetrodotoxins which are poisonous.[129] Some species that prey on bivalve molluscs can transmit paralytic shellfish poisoning.[130] Georg Eberhard Rumpf found few starfish being used for food in the Indonesian archipelago, other than as bait in fish traps, but on the island of "Huamobel"  [sic] the people cut them up, squeeze out the "black blood" and cook them with sour tamarind leaves; after resting the pieces for a day or two, they remove the outer skin and cook them in coconut milk.[123] Starfish are sometimes eaten in China,[131] Japan[132][133] and in Micronesia.[134]

text: As collectables

text: Starfish are in some cases taken from their habitat and sold to tourists as souvenirs, ornaments, curios or for display in aquariums. In particular, Oreaster reticulatus, with its easily accessed habitat and conspicuous coloration, is widely collected in the Caribbean. In the early to mid 20th century, this species was common along the coasts of the West Indies, but collection and trade have severely reduced its numbers. In the State of Florida, O. reticulatus is listed as endangered and its collection is illegal. Nevertheless, it is still sold throughout its range and beyond.[73] A similar phenomenon exists in the Indo-Pacific for species such as Protoreaster nodosus.[135]

text: In industry and military history

text: With its multiple arms, the starfish provides a popular metaphor for computer networks,[136] companies[137][138] and software tools.[139] It is also the name of a seabed imaging system and company.[140]

text: Starfish has repeatedly been chosen as a name in military history. Three ships of the Royal Navy have borne the name HMS Starfish: an A-class destroyer launched in 1894;[141] an R-class destroyer launched in 1916;[142] and an S-class submarine launched in 1933 and lost in 1940.[143] In the World War II, Starfish sites were large-scale night-time decoys created during The Blitz to simulate burning British cities.[144] Starfish Prime was a high-altitude nuclear test conducted by the United States on 9 July 1962.[145]


document_title: The Karate Kid Part II

question_text: where was the karate kid part 2 filmed

question_tokens: where was the karate kid part 2 filmed

root

text: The Karate Kid Part II

text: Plot[edit]

text: Shortly after the All-Valley Karate Tournament, sensei John Kreese becomes furious and attacks Johnny in the parking lot. Miyagi confronts Kreese and passively immobilizes him. Miyagi threatens to strike a deadly blow but instead comically tweaks Kreese's nose and walks away.

tag: p

text: Six months later, Miyagi receives a letter, notifying him that his father is dying. He plans to return to his home village on Okinawa Island, and Daniel accompanies him. Miyagi tells Daniel about why he left Okinawa many years ago. He fell in love with a woman named Yukie, who was arranged to marry his best friend Sato, son of the richest man in the village and fellow karate student of his father. Upon announcing his intentions to marry Yukie, Sato challenged him to a fight to the death. Rather than fight, however, Miyagi left the country.

text: In Okinawa, Miyagi and Daniel are greeted by Chozen Toguchi, who drives Miyagi and Daniel to one of Sato's warehouses and reveals he is Sato's nephew. Sato appears and demands to fight Miyagi, who adamantly refuses. Arriving at the village, Miyagi and Daniel are welcomed by Yukie and her niece Kumiko. They discover that Sato has become a rich industrialist whose supertrawlers have destroyed the local fish population impoverishing the other villagers. They are forced to rent property from Sato, who owns the village's land title. Yukie reveals that she never married Sato, because of her love for Miyagi. After Miyagi's father dies, Sato gives him three days to mourn out of respect before their fight. Miyagi shows Daniel the secret to his family's karate – a handheld drum that twists back and forth illustrating the "drum technique", a block-and-defense karate move that Daniel begins to practice.

text: Daniel accidentally exposes corruption in Chozen's grocery business during an encounter in the village. Chozen later accuses Daniel of insulting his honor, and they have a series of confrontations. Their feud comes to a head when Chozen and his cronies attack Daniel and vandalize Miyagi's family property. The group is quickly defeated and runs off after Miyagi arrives. Miyagi and Daniel plan to return home before the situation gets worse, however Sato shows up with bulldozers and threatens to destroy the village if Miyagi refuses to fight. Forced to comply, Miyagi gives in on the condition that Sato signs the village's land title over to the villagers regardless of the fight's outcome. Sato initially balks, but agrees after Miyagi describes the condition as a "small price" to pay for honor.

text: On the day of the fight, a typhoon appears. Villagers take cover at a nearby shelter, but Sato becomes trapped when his family's dojo is leveled by the storm. Miyagi and Daniel rush to rescue him. Arriving at the shelter, Daniel attempts to rescue a child trapped in a nearby bell tower. Sato orders Chozen to help, but when he refuses, Sato rushes to assist Daniel himself. He disowns his nephew for refusing to cooperate, and an enraged Chozen runs off into the storm in disgrace. The next morning, as the villagers are rebuilding, Sato returns with his bulldozers – only this time to help rebuild. Sato hands over the land title to the village and asks for Miyagi's forgiveness. Miyagi gladly accepts. Daniel and Kumiko approach Sato about hosting the upcoming O-bon festival in a nearby ceremonial castle, and he accepts.

text: While Kumiko is performing a dance at the festival, a now-vengeful Chozen ziplines into the presentation, taking her hostage and demanding to fight Daniel alone. Daniel fights well but is eventually overwhelmed by Chozen. Miyagi, Sato and the crowd respond by twisting handheld drums they brought to the celebration, inspiring Daniel. Seemingly confused, Chozen closes in for the kill, but Daniel is able to deflect Chozen's attacks and land counter-attacks using the drum technique. Daniel grabs the vanquished Chozen, raising his hand and threatening to end Chozen's life saying, "Live or die, man!". Chozen chooses death, but, reminiscent of the way Miyagi handled Kreese earlier, Daniel tweaks Chozen's nose and playfully drops him to the ground. Daniel embraces Kumiko, while Miyagi looks on proudly.

text: Cast[edit]

text:
Ralph Macchio as Daniel LaRusso
Noriyuki "Pat" Morita as Mr. Miyagi
Nobu McCarthy as Yukie
Tamlyn Tomita as Kumiko
Yuji Okumoto as Chozen
Joey Miyashima as Toshio
Marc Hayashi as Taro
Danny Kamekona as Sato
Martin Kove as John Kreese
William Zabka as Johnny Lawrence
Tony O'Dell as Jimmy

tag: ul

text: Other notable cast appearances include B. D. Wong (credited as "Bradd Wong") as an Okinawan boy who invites Daniel and Kumiko to a dance club and Clarence Gilyard as one of the participants in the ice-breaking scene.

text: Production[edit]

text: The opening scene takes place immediately following the finale of the first film to seamlessly tie the two together. It was originally planned as the ending for the first film, although it was not shot until after the second film's production began.[4]

text: Filming[edit]

text: Principal photography took place in Oahu, Hawaii, in the northeastern area of the island known as the "windward side". The local countryside in modern-day Okinawa had been drastically changed due to the presence of military bases, so other locations in both Japan and Hawaii were scouted as alternative filming locations. Filmmakers selected a property in Oahu that was privately owned by a retired local physician who agreed to allow a portion of the land to be used in the film. To form the Okinawan village portrayed in the film, seven authentic replicas of Okinawan houses were constructed along with more than three acres of planted crops. 50 Okinawa-born Hawaii residents were also recruited as film extras. Filming began on September 23, 1985.[5][6]

text: Music[edit]

text: The musical score for The Karate Kid Part II was composed by Bill Conti, who wrote the score for the previous installment. The film's signature tune was Peter Cetera's song "Glory of Love", which was a No. 1 hit in the United States and received an Academy Award nomination for Best Song. When Daniel and Miyagi are being driven by Chozen and his crony Toshio after they arrive in Okinawa, Chozen tunes in the radio of the car until he reaches a station playing "Fascination", the same song to which Ali and Johnny were slow dancing at the high-end country club in the original film. The soundtrack is notable as being the final album released by United Artists Records.

text:
"Glory of Love" (Peter Cetera)
"Rock 'n' Roll Over You" (The Moody Blues)
"Fish for Life" (Mancrab)
"Rock Around the Clock" (Paul Rodgers)
"Let Me at 'Em" (Southside Johnny)
"This is the Time" (Dennis DeYoung)
"Earth Angel" (New Edition)
"Love Theme from The Karate Kid Part II" (Bill Conti)
"Two Looking at One" (Carly Simon)
"The Storm" (Bill Conti)

tag: ol

text: The score, which features 20 tracks, was released separately on compact disc by Varèse Sarabande in a box set in 2007 and 2012.

text: Reception[edit]

text: The Karate Kid Part II opened in 1,323 theaters across North America on June 20, 1986. In its opening weekend, the film ranked first in its domestic box office grossing $12,652,336 with an average of $9,563 per theater. The film earned $20,014,510 in its opening week and ended its run earning a total of $115,103,979 domestically.[7]

text: Critical response[edit]

text: The film has a 42% rating out of 24 reviews on Rotten Tomatoes.[8] Movie-gazette.com gave the film a positive review, stating the film was a "worthy follow-up to the first Karate Kid film, with added interest provided by its exotic locations and characters."[9] The Los Angeles Times also gave the film a positive review, particularly praising Pat Morita's performance as Miyagi and calling the actor "the heart of the movie".[10] However, while picture historian Leonard Maltin agreed with the strength of the performances, he called the film "Purposeless... corny in the extreme — all that's missing from the climax is hounds and ice floes — but made palatable by winning performances. Best for kids." At the Movies gave the film a mixed review, with both critics praising the character Miyagi but criticizing the villains and action scenes. Roger Ebert recommended the movie overall but Gene Siskel did not. [11]

text: Awards and nominations[edit]

text: At the 1987 ASCAP Awards, Bill Conti won Top Box Office Films for the original music, which was released on United Artists Records. It also received a different Academy Award nomination for Best Original Song for "Glory of Love".

text: Video games[edit]

text: A video game adaptation titled The Karate Kid Part II: The Computer Game was released in 1986 by publisher Microdeal on Atari ST and Amiga. It is a fighting game similar to The Way of the Exploding Fist in which the user plays the role of Daniel in five fights based on movie scenes. There are also two mini games with digitized images from the movie: Miyagi catching flies with chopsticks and Daniel breaking an ice block.  [12]

text: The 1987 Nintendo Entertainment System video game The Karate Kid included several elements based on The Karate Kid Part II. Stages 2-4 of the game are based on The Karate Kid Part II, as are two bonus games in which the gamer must break up to six ice blocks. The drum technique exercise shown in the movie is also featured as a challenge in which the gamer must dodge the swinging ax as many times as possible.


document_title: ICC World Twenty20

question_text: where was the last t20 world cup held

question_tokens: where was the last t20 world cup held

text: ICC World Twenty20

text: History[edit]

text: Background[edit]

text: When the Benson & Hedges Cup ended in 2002, the ECB needed another one day competition to fill its place. Cricketing authorities were looking to boost the game's popularity with the younger generation in response to dwindling crowds and reduced sponsorship. It was intended to deliver fast-paced, exciting cricket accessible to thousands of fans who were put off by the longer versions of the game. Stuart Robertson, the marketing manager of the ECB, proposed a 20 over per innings game to county chairmen in 2001 and they voted 11–7 in favour of adopting the new format.[6]

text: The first official Twenty20 matches were played on 13 June 2003 between the English counties in the Twenty20 Cup.[7] The first season of Twenty20 in England was a relative success, with the Surrey Lions defeating the Warwickshire Bears by 9 wickets in the final to claim the title.[8] The first Twenty20 match held at Lord's, on 15 July 2004 between Middlesex and Surrey, attracted a crowd of 27,509, the largest attendance for any county cricket game at the ground other than a one-day final since 1953.[9]

text: Soon after with the adoption of Twenty20 matches by other cricket boards, the popularity of the format grew with unexpected crowd attendance, new regional tournaments such as Pakistan's Faysal Bank T20 Cup and Stanford 20/20 tournament and the financial incentive in the format.

text: The West Indies regional teams competed in what was named the Stanford 20/20 tournament. The event was financially backed by convicted fraudster Allen Stanford, who gave at least US$28,000,000 funding money, the fruit of his massive Ponzi scheme. It was intended that the tournament would be an annual event. Guyana won the inaugural event, defeating Trinidad and Tobago by 5 wickets, securing US$1,000,000 in prize money.[10][11] A spin-off tournament, the Stanford Super Series, was held in October 2008 between Middlesex and Trinidad and Tobago, the respective winners of the English and Caribbean Twenty20 competitions, and a Stanford Superstars team formed from West Indies domestic players; Trinidad and Tobago won the competition, securing US$280,000 prize money.[12][13] On 1 November, the Stanford Superstars played England in what was expected to be the first of five fixtures in as many years with the winner claiming a US$20,000,000 in each match.[14][15]

text: On 17 February 2005 Australia defeated New Zealand in the first men's full international Twenty20 match, played at Eden Park in Auckland. The game was played in a light-hearted manner – both sides turned out in kit similar to that worn in the 1980s, the New Zealand team's a direct copy of that worn by the Beige Brigade. Some of the players also sported moustaches/beards and hair styles popular in the 1980s taking part in a competition amongst themselves for best retro look, at the request of the Beige Brigade. Australia won the game comprehensively, and as the result became obvious towards the end of the NZ innings, the players and umpires took things less seriously – Glenn McGrath jokingly replayed the Trevor Chappell underarm incident from a 1981 ODI between the two sides, and Billy Bowden showed him a mock red card (red cards are not normally used in cricket) in response.

text: Inaugural tournaments[edit]

text: It was first decided that every two years an ICC World Twenty20 tournament is to take place, except in the event of an Cricket World Cup being scheduled in the same year, in which case it will be held the year before. The first tournament was in 2007 in South Africa where India defeated Pakistan in the final. Two Associate teams had played in the first tournament, selected through the 2007 ICC World Cricket League Division One, a 50-over competition. In December 2007 it was decided to hold a qualifying tournament with a 20-over format to better prepare the teams. With six participants, two would qualify for the 2009 World Twenty20 and would each receive $250,000 in prize money.[16] The second tournament was won by Pakistan who beat Sri Lanka by 8 wickets in England on 21 June 2009. The 2010 ICC World Twenty20 tournament was held in West Indies in May 2010, where England defeated Australia by 7 wickets. The 2012 ICC World Twenty20 was won by the West-Indies, by defeating Sri Lanka at the finals. For the first time, a host nation competed in the final of the ICC World Twenty20. There were 12 participants for the title including Ireland and Afghanistan as 2012 ICC World Twenty20 Qualifier. It was the first time the T20 World Cup tournament took place in an Asian country.

text: Expansion to 16 teams[edit]

text: The 2012 edition was to be expanded into a 16 team format however this was reverted to 12.[17] The 2014 tournament, held in Bangladesh was the first to feature 16 teams including all ten full members and six associate members who qualified through the 2013 ICC World Twenty20 Qualifier. However the top eight full member teams in the ICC T20I Championship rankings on 8 October 2012 were given a place in the Super 10 stage. The remaining eight teams competed in the group stage, from which two teams advance to the Super 10 stage.[18][19] Three new teams (Nepal, Hong Kong and UAE) made their debut in this tournament.

text: Format[edit]

text: Qualification[edit]

text: All ICC full members qualify automatically for the tournament, with the remaining places filled by other ICC members through a qualification tournament, known as the World Twenty20 Qualifier. Qualification for the inaugural 2007 World Twenty20 came from the results of the first cycle of the World Cricket League, a 50-over league for ICC associate and affiliate members. The two finalists of the 2007 WCL Division One tournament, Kenya and Scotland, qualified for the World Twenty20 later in the year. A separate qualification tournament was implemented for the 2009 World Twenty20, and has been retained since then. The number of teams qualifying through the World Twenty20 Qualifier has varied, however, ranging from two (in 2010 and 2012) to six (in 2014 and 2016).

text: Final tournament[edit]

text: In each group stage (both the preliminary round and the Super 10 round), teams are ranked against each other based on the following criteria:[20]

text:
Higher number of points
If equal, higher number of wins
If still equal, higher net run rate
If still equal, lower bowling strike rate
If still equal, result of head to head meeting.

text: In case of a tie (that is, both teams scoring the same number of runs at the end of their respective innings), a Super Over would decide the winner. In the case of a tie occurring again in the Super Over, the match is won by the team that has scored the most sixes in their innings. This is applicable in all stages of the tournament, having been implemented during the 2009 tournament. During the 2007 tournament, a bowl-out was used to decide the loser of tied matches.[21]

text: Hosts[edit]

text: The International Cricket Council's executive committee votes for the hosts of the tournament after examining bids from the nations which have expressed an interest in holding the event. After South Africa in 2007, England, West Indies and Sri Lanka hosted the tournament in 2009, 2010 and 2012 respectively. Bangladesh hosted the tournament in 2014.[22] India hosted the last edition of the tournament in 2016.[23]

text: In December 2015, Tim Anderson, the ICC's head of global development, suggested that a future tournament be hosted by the United States. He believed that hosting the event could help spur growth of the game in the country, where it is relatively obscure and faces competition by other sports such as baseball.[24]

text: Results[edit]

text:
Year
Host(s)
Final venue
Final

Winner
Result
Runner-up

2007
Details
 South Africa
Johannesburg
 India
157/5 (20 overs)
India won by 5 runs
Scorecard
 Pakistan
152 all out (19.4 overs)

2009
Details
 England
London
 Pakistan
139/2 (18.4 overs)
Pakistan won by 8 wickets
Scorecard
 Sri Lanka
138/6 (20 overs)

2010
Details
 West Indies
Bridgetown
 England
148/3 (17 overs)
England won by 7 wickets
Scorecard
 Australia
147/6 (20 overs)

2012
Details
 Sri Lanka
Colombo
 West Indies
137/6 (20 overs)
West Indies won by 36 runs
Scorecard
 Sri Lanka
101 all out (18.4 overs)

2014
Details
 Bangladesh
Dhaka
 Sri Lanka
134/4 (17.5 overs)
Sri Lanka won by 6 wickets
Scorecard
 India
130/4 (20 overs)

2016
Details
 India
Kolkata
 West Indies
161/6 (19.4 overs)
West Indies won by 4 wickets
Scorecard
 England
155/9 (20 overs)

2020
Details
 Australia
Melbourne

2021
Details
 India

tag: table

text: Performance of teams[edit]

text:
Team
Appearances
Best result
Statistics[25]

Total
First
Latest
Played
Won
Lost
Tie
NR
Win%

 West Indies
6
2007
2016
1.1 !Champions (2012, 2016)
31
17
12
1(1)
1
58.33

 Sri Lanka
6
2007
2016
1.2 !Champions (2014)
35
22
12
1(1)
0
64.28

 India
6
2007
2016
1.2 !Champions (2007)
33
20
11
1(1)
1
64.06

 Pakistan
6
2007
2016
1.2 !Champions (2009)
34
19
14
1(0)
0
57.35

 England
6
2007
2016
1.2 !Champions (2010)
32
15
16
0
1
48.38

 Australia
6
2007
2016
2.1 !Runner-up (2010)
29
16
13
0
0
55.17

 South Africa
6
2007
2016
3.1 !Semi-final (2009, 2014)
30
18
12
0
0
60.00

 New Zealand
6
2007
2016
3.1 !Semi-final (2007, 2016)
30
15
13
2(0)
0
53.33

 Bangladesh
6
2007
2016
4.1 !Super 8s (2007)
25
5
19
0
1
20.83

 Netherlands
3
2007
2016
4.3 !Super 10s (2014)
12
5
6
0
1
45.45

 Afghanistan
4
2010
2016
4.3 !Super 10s (2016)
14
5
9
0
0
35.71

 Ireland
5
2009
2016
4.3 !Super 8s (2009)
15
3
9
0
3
25.00

 Zimbabwe
5
2007
2016
5.1 !First round (2007, 2010, 2012, 2014, 2016)
12
5
7
0
0
41.66

 Scotland
3
2007
2016
5.2 !First round (2007, 2009, 2016)
7
1
5
0
1
16.66

 Hong Kong
2
2014
2016
5.3 !First round (2014, 2016)
6
1
5
0
0
16.66

   Nepal
1
2014
2014
5.4 !First round (2014)
3
2
1
0
0
66.66

 Oman
1
2016
2016
5.4 !First round (2016)
3
1
1
0
1
50.00

 Kenya
1
2007
2007
5.4 !First round (2007)
2
0
2
0
0
0.00

 United Arab Emirates
1
2014
2014
5.4 !First round (2014)
3
0
3
0
0
0.00

text: Note:

text:
The number in bracket indicates number of wins in tied matches by Super Overs and bowl outs, however these are considered half a win regardless of the result. The win percentage excludes no results and counts ties (irrespective of a tiebreaker) as half a win.
Teams are sorted by best performance, then winning percentage, then (if equal) by alphabetical order

text: Team results by tournament[edit]

text: The ICC does not adjudicate rankings but only rounds a team achieves e.g. Semis, round one etc. The table below provides an overview of the performances of teams in the ICC World Twenty20.

text:
C — Champions
RU — Runners-up
SF — Semi-finalist
R2 — Round 2 (Super 8s, Super 10s)
R1 — Round 1 (Group stage)
 ••  — Qualified but withdrew
 •  — Did not qualify
 ×  — Did not enter / Withdrew

text: The team ranking in each tournament is according to ICC. For each tournament, the number of teams in each finals tournament (in brackets) are shown.

text:
Team

2007
(12)

2009
(12)

2010
(12)

2012
(12)

2014
(16)

2016
(16)

2020
(16)

2021
(16)
Total

 Afghanistan
×
×
R1
R1
R1
R2

4

 Australia
SF
R1
RU
SF
R2
R2
Q

6

 Bangladesh
R2
R1
R1
R1
R2
R2

6

 England
R2
R2
C
R2
R2
RU

6

 Hong Kong
×
×
×
•
R1
R1

2

 India
C
R2
R2
R2
RU
SF

Q
6

 Ireland
•
R2
R1
R1
R1
R1

5

 Kenya
R1
•
•
•
•
•

1

   Nepal
×
×
×
•
R1
•

1

 Netherlands
•
R1
•
•
R2
R1

3

 New Zealand
SF
R2
R2
R2
R2
SF

6

 Oman
×
×
×
•
•
R1

1

 Pakistan
RU
C
SF
SF
R2
R2

6

 Scotland
R1
R1
•
•
•
R1

3

 South Africa
R2
SF
R2
R2
SF
R2

6

 Sri Lanka
R2
RU
SF
RU
C
R2

6

 United Arab Emirates
×
×
•
•
R1
•

1

 West Indies
R1
SF
R2
C
SF
C

6

 Zimbabwe
R1
••
R1
R1
R1
R1

5

text: Debut of teams[edit]

text: Team appearing for the first time, in alphabetical order per year.

text:
Year
Debutants
Total

2007
 Australia,  Bangladesh,  England,  India,  Kenya,  New Zealand,
 Pakistan,  Scotland,  South Africa,  Sri Lanka,  West Indies,  Zimbabwe
12

2009
 Ireland,  Netherlands
2

2010
 Afghanistan
1

2012
none
0

2014
 Hong Kong,    Nepal,  United Arab Emirates
3

2016
 Oman
1

2020
TBD
TBD

2021
TBD
TBD

Total

19

text: Statistics and records[edit]


document_title: Crumple zone

question_text: where are the crumple zones located in a car

text: Crumple zone

text: Early development history[edit]

text: The crumple zone concept was invented and patented by the Austrian Mercedes-Benz engineer Béla Barényi originally in 1937 before he worked for Mercedes-Benz and in a more developed form in 1952.[13] The 1953 Mercedes-Benz "Ponton"[14] was a partial implementation of his ideas by having a strong deep platform to form a partial safety cell - patented in 1941.[13] The Mercedes-Benz patent number 854157, granted in 1952, describes the decisive feature of passive safety. Barényi questioned the opinion prevailing until then, that a safe car had to be rigid. He divided the car body into three sections: the rigid non-deforming passenger compartment and the crumple zones in the front and the rear. They are designed to absorb the energy of an impact (kinetic energy) by deformation during collision.[15] The first Mercedes-Benz carbody developed using this patent was the 1959 Mercedes W111 “Tail Fin” Saloon.[13] The safety cell and crumple zones were achieved primarily by the design of the longitudinal members: these were straight in the centre of the vehicle and formed a rigid safety cage with the body panels, the front and rear supports were curved so they deformed in the event of an accident, absorbing part of the collision energy and preventing the full force of the impact from reaching the occupants.[13][16][17][18]

text: A more recent development was for these curved longitudinal members is to be weakened by vertical and lateral ribs to form telescoping 'crash can' or 'crush tube' deformation structures.

text: Function[edit]

text: Crumple zones work by managing crash energy, absorbing it within the outer parts of the vehicle, rather than being directly transferred to the occupants, while also preventing intrusion into or deformation of the passenger cabin. This better protects car occupants against injury. This is achieved by controlled weakening of sacrificial outer parts of the car, while strengthening and increasing the rigidity of the inner part of the body of the car, making the passenger cabin into a 'safety cell', by using more reinforcing beams and higher strength steels. Impact energy that does reach the 'safety cell' is spread over as wide an area as possible to reduce its deformation. Volvo introduced the side crumple zone with the introduction of the SIPS (Side Impact Protection System) in the early 1990s.

text: When a vehicle and all its contents, including passengers and luggage are travelling at speed, they have inertia / momentum, which means that they will continue forward with that direction and speed (Newton's first law of motion).[20] In the event of a sudden deceleration of a rigid framed vehicle due to impact, unrestrained vehicle contents will continue forwards at their previous speed due to inertia, and impact the vehicle interior, with a force equivalent to many times their normal weight due to gravity. The purpose of crumple zones is to slow down the collision and to absorb energy to reduce the difference in speeds between the vehicle and its occupants.[21]

text: Seatbelts restrain the passengers so they don't fly through the windshield, and are in the correct position for the airbag and also spread the loading of impact on the body. Seat belts also absorb passenger inertial energy by being designed to stretch during an impact, again to reduce the speed differential between the passenger's body and their vehicle interior.[22] In short: a passenger whose body is decelerated more slowly due to the crumple zone (and other devices) over a longer time survives much more often than a passenger whose body indirectly impacts a hard, undamaged metal car body which has come to a halt nearly instantaneously. It is like the difference between slamming someone into a wall headfirst (fracturing their skull) and shoulder-first (bruising their flesh slightly) is that the arm, being softer, has tens of times longer to slow its speed, yielding a little at a time, than the hard skull, which isn't in contact with the wall until it has to deal with extremely high pressures. The stretching of seatbelts while restraining occupants during an impact, means that it is necessary to replace them if a vehicle is repaired and put back on the road after a collision. They should also be replaced if their condition has deteriorated e.g. through fraying or mechanical or belt mounting faults. In New Zealand it is officially mandatory to replace worn inertia reel type seatbelts only with 'webbing grabber' type belts that have less play and are more effective on older cars.[23] Newer cars have electronically fired pre-tension seatbelts that are timed to work with the airbag firing. Buying used seatbelts is not a good idea even in countries where it is legal to do so, because they may have already been stretched in an impact event and may not protect their new users as they should.

text: The final impact after a passenger's body hits the car interior, airbag or seat belts is that of the internal organs hitting the ribcage or skull due to their inertia. The force of this impact is the way by which many car crashes cause disabling or life-threatening injury. Other ways are skeletal damage and blood loss, because of torn blood vessels, or damage caused by sharp fractured bone to organs and/or blood vessels. The sequence of energy-dissipating and speed-reducing technologies—crumple zone — seat belt — airbags — padded interior—are designed to work together as a system to reduce the force of the impact on the outside of the passenger(s)'s body and the final impact of organs inside the body. In a collision, slowing down the deceleration of the human body by even a few tenths of a second drastically reduces the force involved. Force is a simple equation: Force = mass X acceleration. Cutting the deceleration in half also cuts the force in half. Therefore, changing the deceleration time from .2 seconds to .8 seconds will result in a 75 percent reduction in total force.[24]

text: A misconception about crumple zones sometimes voiced[citation needed] is that they reduce safety for the occupants of the vehicle by allowing the body to collapse, therefore risking crushing the occupants. In fact, crumple zones are typically located in front of and behind the main body of the car (which forms a rigid 'safety cell'), compacting within the space of the engine compartment or boot/trunk.  Modern vehicles using what are commonly termed 'crumple zones' provide far superior protection for their occupants in severe tests against other vehicles with crumple zones and solid static objects than older models or SUVs that use a separate chassis frame and have no crumple zones.

text: They do tend to come off worse when involved in accidents with SUVs without crumple zones because most of the energy of the impact is absorbed by the vehicle with the crumple zone — however, even for the occupants of the 'worse off' car, this will still often be an improvement — as the result of two vehicles without crumple zones colliding will usually be more hazardous to both vehicle's occupants than a collision that is at least partly buffered.[citation needed]

text:
Another problem is 'impact incompatibility' where the 'hard points' of the ends of chassis rails of SUVs are higher than the 'hard points' of cars, causing the SUV to 'override' the engine compartment of the car.[19]  In order to tackle this problem, more recent SUV/off-roaders incorporate structures below the front bumper designed to engage lower-height car crumple zones.[25]Volvo XC70 low level front safety cross members shown here[26]
Volvo's press release about this feature:
 'Lower cross-member that helps protects lower cars: The front suspension subframe in the new Volvo XC60 is supplemented with a lower cross-member positioned at the height of the beam in a conventional car. The lower cross-member strikes the oncoming car's protective structure, activating its crumple zone as intended so the occupants can be given the maximum level of protection.'

text: Low speed impact absorption[edit]

text: The front of the bumper is designed to withstand low speed collisions, e.g. As in parking bumps to prevent permanent damage to the vehicle. This is achieved by elastic elements, such as the front apron. In some vehicles, the bumper is filled with foam or similar elastic substances. This aspect of design has received more attention in recent years as NCAP crash assessment has added pedestrian impacts to its testing regime. The reduction of rigid support structures in pedestrian impact areas has also been made a design objective.

text: In the case of less severe collisions (up to approx. 20 km / h), the bumper and outer panel design should ensure that the crumple zone and the load-bearing structure of the vehicle is damaged as little as possible and repairs can be carried out as cheaply as possible. For this purpose, so-called crash tubes or crash boxes are used for mounting bumpers. Crashtubes consist of a hollow steel profile, which transforms the incident energy by rolling up the profile.

text: Computer modelled crash simulation[edit]

text: In the early 1980s, using technology developed for the aerospace and nuclear industries, German car makers started complex computer crash simulation studies, using finite element methods simulating the crash behaviour of individual car body components, component assemblies, and quarter and half cars at the   body in white(BIW) stage. These experiments culminated in a joint project by the Forschungsgemeinschaft Automobil-Technik (FAT), a conglomeration of all seven German car makers (Audi, BMW, Ford, Mercedes-Benz, Opel (GM), Porsche, and Volkswagen), which tested the applicability of two emerging commercial crash simulation codes. These simulation codes recreated a frontal impact of a full passenger car structure (Haug 1986) and they ran to completion on a computer overnight. Now that turn-around time between two consecutive job-submissions (computer runs) did not exceed one day, engineers were able to make efficient and progressive improvements of the crash behaviour of the analyzed car body structure. The drive for improved crash worthiness in Europe has accelerated from the 1990s onwards, with the 1997 advent of Euro NCAP, with the involvement of Formula One motor racing safety expertise.

text: 'Sleds' inside safety cells[edit]

text:
The 2004 Pininfarina Nido Experimental Safety Vehicle locates crumple zones inside the survival cell. Those interior crumple zones decelerate a sled-mounted survival cell.[20]
Volvo has also been developing this idea for use in small cars. Their driver's seat is mounted to what is basically a 'sled' on a rail, with shock absorbers in front of it. In an impact, the whole "sled" of driving seat and belted in driver, slides forward up to 8 inches, and the shock absorbers dissipate the peak shock energy of the impact, lengthening the deceleration time for the driver. Simultaneously, the steering wheel and the driver's side dashboard slide forward to make room for the driver, as he is thrown forwards stretching the seatbelt. Combined with a front crumple zone and airbag, this system could greatly reduce the forces acting on the driver in a frontal impact.[27]