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Kitefin shark
The kitefin shark or seal shark (''Dalatias licha'') is a species of dogfish shark in the family Dalatiidae, and the only species in its genus. It is found sporadically around the world, usually close to the sea floor at depths of . With a sizable oil-filled liver to maintain neutral buoyancy, this shark is able to cruise slowly through the water while expending little energy. The kitefin shark has a slender body with a very short, blunt snout, large eyes, and thick lips. Its teeth are highly differentiated between the upper and lower jaws, with the upper teeth small and narrow and the lower teeth large, triangular, and serrated. Its typical length is .
Armed with large teeth and a strong bite, the kitefin shark is a powerful, solitary predator that takes many different types of prey, ranging from bony fishes, sharks and rays, to cephalopods, crustaceans, polychaete worms, siphonophores, and possibly carrion. It also takes bites out of animals larger than itself, similar to its smaller relative, the cookiecutter shark (''Isistius brasiliensis''). This shark is aplacental viviparous and gives birth to 10–14 young. The kitefin shark is fished commercially for its meat, skin, and liver oil, primarily by Portugal and Japan. A fishery targeting this species existed off the Azores from the 1970s to the 1990s, but collapsed due to overfishing and falling liver oil prices; the rapid depletion of the Azores stock is often cited as an example of the susceptibility of deep-sea sharks to human exploitation. The low reproductive rate of this species renders it susceptible to overfishing and, coupled with known population declines, has led it to be assessed as Near Threatened by the International Union for Conservation of Nature (IUCN).
==Taxonomy==
The kitefin shark was originally described as ''Squalus licha'' by French naturalist Pierre Joseph Bonnaterre, in his 1788 ''Tableau encyclopédique et méthodique des trois regnes de la nature''; the type specimen from "Le cap Breton" has since been lost. This species was later placed in its own genus, ''Dalatias'', which came from the synonymy of Constantine Rafinesque's 1810 ''Dalatias sparophagus'' with ''S. licha''. However, some authorities dispute this on the grounds that ''D. sparophagus'' is a ''nomen dubium'', and prefer to use the next available genus name ''Scymnorhinus''. The genus name ''Dalatias'' is derived from the Greek ''dalos'' or ''dalou'', meaning "torch".〔 The specific epithet ''licha'' comes from ''la liche'', the French name for this shark. Additional common names used for the kitefin shark include black shark and darkie Charlie.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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