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The Ganges shark (''Glyphis gangeticus'') is a critically endangered species of requiem shark found in the Ganges River and the Brahmaputra River of India. It is often confused with the more common bull shark (''Carcharhinus leucas''), which also inhabits the Ganges River and is sometimes incorrectly referred to as the Ganges shark. Unlike bull sharks, which need to migrate to salt water to reproduce, species in the genus ''Glyphis'' are true river sharks. The genus contains a total of six known species, only half of which are described. ==Physical appearance== ''G. gangeticus'' is a little-known species that is yet to be adequately described. Its size at birth is 56 to 61 cm, growing to an estimated 178 cm at maturity, with a maximum size of about 204 cm. It is worth noting that the size at birth or maturity is unknown for any other ''Glyphis'' species.〔 A typical requiem shark in its external appearance, it is stocky, with two spineless dorsal fins and an anal fin. The first dorsal fin originates over the last third of the pectoral fins, with a free rear tip that is well in front of the pelvic fins. The second dorsal fin is relatively large, but much smaller than the first (about half the height). The anal fin is slightly smaller than the second dorsal fin and the pectoral fins are broad. There is a longitudinal upper precaudal pit, but no interdorsal ridge. It is uniformly grey to brownish in color, with no discernible markings.〔 Its snout is broadly rounded and much shorter than the width of its mouth. The mouth is long, broad, and extends back and up towards the eyes.〔 Its eyes are minute, suggesting that it may be adapted to turbid water with poor visibility, such as occurs in the Ganges River and the Bay of Bengal. It has internal nictitating eyelids.〔 The upper teeth have high, broad serrated triangular cusps and the labial furrows are very short. The lower front teeth have long, hooked, protruding cusps with unserrated cutting edges along the entire cusp, but without spearlike tips and with low cusplets on feet of crowns. The tooth row counts are 32–37/31–34. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Ganges shark」の詳細全文を読む スポンサード リンク
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