CARCHARHINID

also called requiem shark, any member of the shark family Carcharhinidae, which includes about 13 genera and numerous species found worldwide. Carcharhinids are found primarily in warm and temperate ocean waters, though a few species inhabit fresh or brackish water. The Carcharhinidae is the largest family of sharks and includes the majority of sharks alive today. Some of the larger carcharhinids, such as the blacktip, whitetip, Lake Nicaragua, and lemon sharks, are potentially dangerous to humans. Carcharhinids are typically sharklike in appearance, having two dorsal fins, an elongate upper tail lobe, and single-cusped, blade-shaped teeth. Like other sharks, they are carnivorous, preying on fishes and various other animals. The species range in length from about 1.5 to 5.5 m (4.5 to 18 feet). The classification of many, especially the gray sharks, or whalers (Carcharhinus), is uncertain and may be revised after further study. A number of carcharhinids, such as the blue shark and tiger shark (qq.v.), are well known. Others are described below. The name blacktip shark applies to any of several species with dark fin tips. Two Atlantic species are the small blacktip (Carcharhinus limbatus), which grows to about 2.5 m, and the somewhat larger large blacktip, or spinner shark (C. maculipinnis). One small species, C. melanopterus, is found in shallow Indo-Pacific waters. The bull shark (C. leucas), also called cub, or ground, shark, dwells inshore in the western Atlantic and swims as much as 250 km (160 miles) up rivers. It is blunt-snouted, pale to dark gray above, and white below. The bull shark grows to about 3.5 m. The Lake Nicaragua shark, which is considered a race of bull shark by some, is found in Lake Nicaragua. It is stout, blunt-nosed, gray in colour, and grows to 2.5 to 3 m. The lemon shark (Negaprion brevirostris) is a common western Atlantic species that dwells inshore and is occasionally found in fresh or brackish waters. It is yellowish and grows to about 3.5 m. The soupfin shark (Galeorhinus zyopterus) is a North American Pacific species that was once heavily fished for its vitamin-rich liver oil. It is related to the school shark (G. australis), a valuable Australian food fish, and the tope (G. galeus), a British game fish. All three species are gray or brownish, grow to about 2 m long, and are often found in schools. The whitetip shark (C. longimanus) frequents all oceanic tropical waters, in which it is probably the most commonly occurring large shark. The whitetip shark has long pectoral fins; a large, rounded first dorsal fin; and is coloured white below and olive, gray, brown, or bluish above, with white fin tips. It grows to about 3.5 m.