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Pondicherry shark
The Pondicherry shark (''Carcharhinus hemiodon'') is an extremely rare, possibly extinct, species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than , and it has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first dorsal fin, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its pectoral fins, second dorsal fin, and caudal fin lower lobe.
Not seen since 1979, the Pondicherry shark was once found in Indo-Pacific coastal waters from the Gulf of Oman to New Guinea, and may have entered fresh water. Fewer than 20 specimens are available for study, and most aspects of its natural history are unknown. It probably feeds on bony fishes, cephalopods, and crustaceans, and gives birth to live young with the embryos forming a placental connection to their mother. The International Union for Conservation of Nature (IUCN) has listed the Pondicherry shark as Critically Endangered. If it still survives, it would be threatened by intense and escalating fishing pressure throughout its range.
==Taxonomy==
The first scientific description of the Pondicherry shark was authored by German biologists Johannes Müller and Jakob Henle in their 1839 ''Systematische Beschreibung der Plagiostomen''. Their account was based on a long immature male from Puducherry (formerly Pondicherry), India and three more paratypes from the same region. Müller and Henle attributed the name for the new species, ''Carcharias (Hypoprion) hemiodon'', to French zoologist Achille Valenciennes. The specific epithet ''hemiodon'' is derived from the Greek ''hemi'' ("half") and ''odon'' ("tooth").〔〔〔
In 1862, Theodore Gill elevated ''Hypoprion'' to the rank of full genus and also placed the Pondicherry shark in its own genus, ''Hypoprionodon'', based on the relative positions of the dorsal and pectoral fins. Subsequent authors generally accepted Gill's first revision but not his second, and thus this species became known as ''Hypoprion hemiodon''. In 1985, Jack Garrick followed up on earlier taxonomic work by Leonard Compagno and synonymized ''Hypoprion'' with ''Carcharhinus''.〔 Another common name for the Pondicherry shark is long nosed shark.〔
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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