The prickly shark (Echinorhinus cookei) is one of the two species of sharks in the family Echinorhinidae (the other is the bramble shark), found in the Pacific Ocean over continental and insular shelves and slopes, and in submarine canyons. Bottom-dwelling in nature, it generally inhabits cool water 100–650 m (330–2,130 ft) deep, but also frequently enters shallower water in areas such as Monterey Bay off California. This stocky, dark-colored shark grows up to 4.0 m (13.1 ft) long, with two small dorsal fins positioned far back on its body and no anal fin. It is characterized by a dense covering of thorn-like dermal denticles, hence its common name. Individual sharks have a small home range and tend to remain within a given local area. Since it moves slowly, it may use suction to capture prey. The prickly shark is not known to be dangerous to humans and has minimal economic value. It is caught incidentally by commercial deepwater fisheries, which are expanding and may potentially threaten its population. Thus, the International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened. The prickly shark has a flabby and cylindrical body, with the adults markedly bulkier than juveniles, and a short, moderately flattened head. The nostrils are placed far apart and preceded by small flaps of skin. The spiracles are tiny and positioned well behind the eyes, which lack nictitating membranes. The mouth forms a broad arch, with very short furrows at the corners. There are 21–25 and 20–27 tooth rows in the upper and lower jaws respectively. The knife-like teeth each have a strongly angled main cusp flanked by up to three smaller cusplets on either side; the lateral cusplets are absent in young sharks. There are five pairs of gill slits, with the fifth pair the longest. It may reach a length of 4.0 m (13.1 ft). The maximum recorded weight is 266 kg (590 lb) for a 3.1 m (10 ft) long female. The prickly shark is widely distributed around the Pacific Ocean. In the western and central Pacific, it has been reported off Japan, Taiwan, Victoria and Queensland in Australia, and New Zealand, as well as around the islands of Palau, New Caledonia, Tonga, Hawaii, and possibly the Gilberts. In the eastern Pacific, it is known to occur from Oregon to El Salvador (including the Gulf of California), around the Cocos and Galapagos Islands, and off Peru and Chile. This species generally seems to be uncommon; an exception is in Monterey Canyon off California, where sharks of both sexes are abundant throughout the year.

prickly_shark.txt · Last modified: 2014/02/07 14:27 by grinder
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