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knifetooth sawfish
The knifetooth sawfish (''Anoxypristis cuspidata''), also known as the pointed sawfish or narrow sawfish, is a species of sawfish in the family Pristidae, part of the Batoidea, a superorder of cartilaginous fish that includes the rays and skates. The sawfishes are characterised by the long, narrow, flattened rostrum or extension on their snout. This is lined with sharp transverse teeth, arranged in a way that resembles the teeth of a saw. It is found in the shallow coastal waters and estuaries of the Indo-West Pacific, ranging from the Red Sea and the Persian Gulf to southern Japan, Papua New Guinea and northern Australia. It is the only member of the genus ''Anoxypristis'', but was previously included in the genus ''Pristis''. Compared to that genus, ''Anoxypristis'' has a narrower rostral saw with numerous teeth on the distal part and no teeth on the basal quarter. This endangered species reaches a length of up to .
==Description==
The knifetooth sawfish grows to a maximum length of about . Its body is generally shark-like but its most obvious feature is the flattened head which is extended forward in a blade-like bony snout with, in Australian waters, 18 to 22 pairs of sideways-facing teeth, though elsewhere there may be as many as 25.〔 These teeth are short and flat and are roughly triangular in shape. The blade does not taper towards its point and the basal quarter is devoid of teeth. The nostrils are narrow and partially concealed by nasal flaps. The skin of young sawfish is smooth but on older individuals it is sparsely covered in dermal denticles. The dorsal (upper) side of the fish is greyish and the ventral (lower) side a rather paler grey colour and the fins are also pale. The rostrum is grey with white teeth and sometimes has a chocolate-brown base portion.
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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