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Author: (Ranzani, 1839)

Field Marks:
A small grey shark with second dorsal small and with origin over anal midbase, anal base without long preanal ridges, labial furrows short, hyomandibular pores not conspicuous, snout long and pointed, small pectoral fins, anal fin deeply notched, 14 to 15 rows of anteroposterior teeth in each side of both jaws.

Diagnostic Features:
A small slender species (less than 1.5 m). Snout moderately long and moderately pointed; internarial width 1.2 to 1.8 times in preoral length; eyes circular and large, their length 1.6 to 2.5% of total length; anterior nasal flaps expanded as slender, pointed lobes; upper labial furrows short and inconspicuous; hyomandibular line of pores just behind mouth corners not conspicuously enlarged; gill slits short, the third 2.8 to 3.4and of total length and a third or less of first dorsal base; usually 14 to 15/14 to 15 rows of anteroposterior teeth in each jaw half but varying from 13 to 15/13 to 15; upper teeth with narrow, strongly serrated, semierect to oblique, high cusps, and crown feet with slightly coarser serrations and postlateral cusplets; lower teeth with semierect or oblique, narrow serrated cusps and transverse roots. No interdorsal ridge. First dorsal fin large and falcate, with bluntly pointedapex and posterior margin curving ventrolaterally from fin apex; origin of first dorsal fin usually over the pectoral inner margins but sometimes slightly posterior to pectoral insertion; inner margin of first dorsal moderately long, half of dorsal base or slightly less; second dorsal fin moderate-sized and fairly low, its height 2.2 to 2.8% of total length, its inner margin moderately long and 1.4 to 1.9 times its height; origin of second dorsal over or slightly behind anal midbase; pectoral fins small, falcate, with narrowly rounded or pointed apices, length of anterior margins about 13 to 16% of total length; 96 to 135 total vertebral centra, 41 to 61 precaudal centra. Colour grey above, light below, tips of pectoral, dorsal and caudal fins frequently dusky or blackish, but not conspicuously marked; white flank band inconspicuous.

Gieographical Distribution:
Western Atlantic: Northern Gulf of Mexico coastally to southern Brazil, not in Caribbean Islands. Eastern Pacific: Gulf of California to Peru, not at offshore islands.

Habitat and Biology:
A common inshore tropical shark of the American continental shelves, found near the bottom at depths from close inshore down to at least 36 m; favours mud bottom and especially estuaries.

Viviparous, with a yolk sac placenta; number of young 2 to 7. In Brazilian waters born in late spring or summer, with a gestation period of 10 months or more. About 52% of young are males.

A harmless shark, primarily a fish-eater, that eats sardines,sea catfish, croakers, jacks, grunts, other small sharks including young hammerheads and sharpnose sharks, and shrimp.

Size:
Probably not exceeding 150 cm; males maturing between 75 and 78 cm and reaching 117 cm; females mature at 84 cm or below and reaching 134 cm; size at birth between 31 and 40 cm.

Interest to Fisheries:
Caught incidentally throughout its range, with longlines, and utilized fresh, fresh frozen and dried salted for human consumption; the liver is also extracted for oil (vitamins) and carcasses are used for fishmeal.

Remarks:
Garrick (1982) noted that this species also occurs in the western Pacific, off Viet Nam (Ho Chi Minh City), Borneo (Baram) and Thailand (Bangkok).

Examination of a Borneo specimen referred by Garrick to porosus and Garrick's published data on the Vietnamese and Thai specimens of porosus strongly suggests that these specimens are not conspecific with C. porosus, but represent a C. borneensis-like species that is apparently not referable to C. borneensis either. These specimens may represent an undescribed small species of Carcharhinus.

Type material:
Holotype: Male of 1170 mm, presumably adult, lost? Type Locality: Brazil.

Smalltail shark (Carcharhinus porosus)