Galápagos Shark

One of the largest species in its genus, the Galapagos shark commonly reaches 3.0 m (9.8 ft) long. The maximum length has been variously recorded as 3.3 m (11 ft) to 3.7 m (12 ft). The maximum recorded weight is 195 kg (430 lb) for a 3.0 m (9.8 ft) long female (longer specimens having apparently been unweighed). This species has a slender, streamlined body typical of the requiem sharks. The snout is wide and rounded, with indistinct anterior nasal flaps. The eyes are round and of medium size. The mouth usually contains 14 tooth rows (range 13–15) on either side of both jaws, plus one tooth at the symphysis (where the jaw halves meet). The upper teeth are stout and triangular in shape, while the lower teeth are narrower; both upper and lower teeth have serrated edges. The first dorsal fin is tall and moderately falcate (sickle-shaped), with the origin over the pectoral fin rear tips. It is followed by a low midline ridge running to the second dorsal fin. The second dorsal fin originates over the anal fin. The pectoral fins are large with pointed tips. The coloration is brownish gray above and white below, with a faint white stripe on the sides. The edges of the fins are darker but not prominently marked. …

The Galapagos shark is found mainly off tropical oceanic islands. In the Atlantic Ocean, it occurs around Bermuda, the Virgin Islands, Madeira, Cape Verde, Ascension Island, Saint Helena and São Tomé Island. In the Indian Ocean, it is known from Walter's Shoal off southern Madagascar. In the Pacific Ocean, it occurs around Lord Howe Island, the Marianas Islands, the Marshall Islands, the Kermadec Islands, Tupai, the Tuamotu Archipelago, the Juan Fernández Islands, the Hawaiian Islands, the Galapagos Islands, Cocos Island, the Revillagigedo Islands, Clipperton Island, and Malpelo. There are a few reports of this species in continental waters off the Iberian Peninsula, Baja California, Guatemala, Colombia, and eastern Australia. The Galapagos shark is generally found over continental and insular shelves near the coast, preferring rugged reef habitats with clear water and strong converging currents. It is also known to form groups around rocky islets and seamounts. This species is capable of crossing the open ocean between islands and has been reported at least 50 km (31 mi) from land. Juveniles seldom venture deeper than 25 m (82 ft), while adults have been reported to a depth of 180 m (590 ft).

The Galapagos shark is often the most abundant shark in shallow island waters. In their original description of this species, Snodgrass and Heller noted that their schooner had taken "several hundred" adult Galapagos sharks and that "thousands" more could be seen in the water. At the isolated Saint Peter and Paul Rocks along the Mid-Atlantic Ridge, the resident Galapagos sharks have been described as "one of the densest shark populations of the Atlantic Ocean". At some locations they form large aggregations, though these are not true schools. During group interactions, Galapagos sharks are dominant to blacktip sharks (C. limbatus) but deferent to silvertip sharks (C. albimarginatus) of equal size. When confronted or cornered, the Galapagos shark may perform a threat display similar to that of the grey reef shark, in which the shark performs an exaggerated, rolling swimming motion while arching its back, lowering its pectoral fins, puffing out its gills, and gaping its jaw. The shark may also swing its head from side to side, so as to keep the perceived threat within its field of vision. A known parasite of the Galapagos shark is the flatworm Dermophthirius carcharhini, which attaches to the shark's skin. In one account, a bluefin trevally (Caranax melampygus) was seen rubbing against the rough skin of a Galapagos shark to rid itself of parasites.

Feeding. …