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Silvertip shark

Posted on: April 24, 2010

Above the Silvertip shark

1. The silvertip shark is found in the western Indian ocean and the Pacific ocean. Silvertip sharks are found at a depth of 30–800 m (100–2,600 ft). But are mostly found around island and coral banks, reef drop-offs. Young silvertip are often found in coastal shallows or lagoons while adults occur in deeper water.

2. The silvertip shark is robust and streamlined shark with a moderately long broad snout and large round eyes. And their five gills are short. they have 12-14 tooth rows on each side of both of their jaws. With 1-2 small teeth the middle of their jaws. The upper teeth are broad with triangular cusps and the lower teeth have erect cusps with fine serrations. The first dorsal fin is large and triangular or slightly forward of the free pectoral fin tips. There is a ridge between the first and second dorsal fins. The pectoral fins are longer than in most sharks and sickle-like in shape with pointed tips.
The silvertip is a blue-gray above with a bronze sheen and white below and white tips and borders on all fins. Silvertip sharks can grow up to 3 m (9.8 ft) long but mostly measure 2.0–2.5 m (6.6–8.2 ft) in length. The maximum reported weight is 162.2 kg (358 lbs). Females are larger than males.

3. The silvertip is usually found in pairs or alone. Small groups of adult females have been seen in deep water. Individual silvertip sharks behave very aggressively towards one another and many are heavily scarred. There are also reported to dominate Galapagos sharks and blacktip sharks. Like the grey reef shark the silvertip sharks sometimes perform a threat display if pursued by divers warning that it is prepared to attack. The display begins with the shark turning away to a distance of 15 m (50 ft) before turning and charging towards the perceived threat. The shark brakes, turns broadside, drops its pectoral fins, gapes its jaws, lowers the posterior two-thirds of its body and “shivers”. The last two elements of this display are unique to this species the “shivering” may serve to emphasize its white fin markings. If the diver persists the shark may rapidly close in and slash with its upper teeth.

4. The diet of the silvertip shark consists primarily of bony fishes such as grouper, mackerel, tuna, escolars, lantern fish, flying fish, wrasses, and soles. Eagle rays, smaller sharks and octopus are occasionally taken. The differently shaped dentition in their upper and lower jaws allows them to tackle large prey, gripping and sawing off chunks of flesh with violent twists and turns. Silvertip sharks have been observed swimming around other groups of feeding sharks of other species and occasionally dashing in to steal food.

5. Like other sharks the silvertip shark is viviparous which means once the embryos exhaust their supply of yolk the depleted yolk sac develops into a placental connection through which the mother delivers nourishment. In the southern hemisphere mating and parturition both occur in summer. Females bear litters of 1–11 (usually 5–6) young after a gestation period of about one year. The newborns have been reported to measure 63–68 cm (25–27 in) and 73–81 cm (29–32 in) long and are found in shallower water than adults. Males have been reported to be sexually mature at 1.6–1.8 m (5.2–5.9 ft) or 1.9–2.0 m (6.2–6.6 ft) long and females at 1.6–2.0 m (5.2–6.6 ft) long.

6. The silvertip shark can be dangerous to humans. Often several silvertip sharks will rush up from deep water to inspect divers when they first enter the water and may approach quite close. This species has also been known to circle or pursue divers. In one experiment a large silvertip shark tore the leg off of a dummy dressed in SCUBA gear. As of 2008 four provoked attacks on humans and none was fatal.


All of this info is from http://en.wikipedia.org/wiki/Silvertip_shark

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