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Taxonomische classification
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Author: (Whitley, 1945 )

Field Marks:
A moderate-sized, greyish or brownish 'grey shark' with a short, bluntly rounded snout, horizontally oval eyes, anteroposterior tooth rows usually 12 to 13/12 to 13 in each jaw half, no interdorsal ridge, a moderately large second dorsal with a short rear tip, and black edges on the dorsal fins and caudal and black tips on the upper and lower caudal lobe and pectoral fin.

Diagnostic Features:
A moderate-sized, fairly stocky species (to 1.5 m). Snout short and bluntly rounded; internarial width 1.1 to 1.2 times in preoral length; eyes horizontally oval and fairly large, their length 1.9 to 3.3% of total length; anterior nasal flaps moderately elongated and expanded as nipple-shaped lobes; upper labial furrows short and inconspicuous; hyomandibular line of pores just behind mouth corners not conspicuously enlarged; gill slits moderate-sized, the third 2.9 to 3.4% of total length and less thana third of first dorsal base; usually 12 to 13/12 to 13 rows of anteroposterior teeth in each iaw half but varying from 12 to 14/11 to 13; upper teeth with narrows strongly serrated, oblique, moderately high cusps, and crown feet with coarser serrations and cusplets; lower teeth with erect to oblique, narrow serrated cusps and transverse roots. No interdorsal ridge. First dorsal fin large and falcate, with a narrowly rounded or pointed apex and posterior margin curving ventrally from fin apex; origin of first dorsal fin over or somewhat in front of pectoral free rear tips; inner margin of first dorsal short, less than a third of dorsal base; second dorsal fin large and high, its height 3.1 to 4.1% of total length, its inner margin short and 1 to 1.1 times its height; origin of second dorsal about over anal origin; pectoral fins moderately large, narrow and falcate, with narrowly rounded or pointed apices, length of anterior margins about 17 to 19% of total length; 160 to 171 total vertebral centra, 86 to 90 precaudal centra. Colour grey or light brown above, white below; dorsal, caudal and pectoral fins with black margins, expanded apically to black tips on caudal lobes and pectorals; probably a conspicuouswhite band on flank.

Geographical Distribution:
Eastern Indian Ocean and western South Pacific: Australia (Queensland, western and northern Australia), Ugi and Solomon Islands.

Habitat and Biology:
The nervous shark is a little-known South Pacific reef shark that may have a wider distribution. It apparently lives in shallow water on the continental and insular shelves, but may range in deeper water. According to Whitley (1940), they are rather skittish and timid when accosted by people, hence the name he bestowed on them. Presumably viviparous. Eats small fishes, including lizardfish and smelt-whiting (Sillago), and crabs. Probably harmless or minimally hazardous to people.

Size:
Maximum about 150 cm, adult females 120 to 150 cm; size at birth between 35 and 39 cm.

Interest to Fisiveries:
Unknown.

Remarks:
This species is rather similar to the blacktipped reef shark, Carcharhinus melanopterus, but lacks the conspicuous highlighted black blotch on its first dorsal fin, and has lower vertebral counts.

Type material:
Holotype: Australian Museum, Sydney, IB. 1622, 918 mm female (skin and teeth only). Type Locality: Shark Bay, Herald Bight, Western Australia.

Nervous shark (Carcharhinus cautus)