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Archive for May 13th, 2010

Above the Thresher shark

1. There are three types thresher shark they are Pelagic thresher, Bigeye thresher, Common thresher.

2. Although occasionally sighted in shallow, inshore waters, thresher sharks they prefer the open ocean and will not go no deeper than 500 meters (1,600 ft). Common threshers tend to be more common in coastal waters over continental shelves. In the North Pacific, common thresher sharks are found along the continental shelves of North America and Asia. They are rare in the Central and Western Pacific. In the warmer waters of the Central & Western Pacific, bigeye and pelagic thresher sharks are more common.

3. The Common thresher which may reach a length of 6.1 meters (20 ft) and a weight of over 500 kilograms (1,100 lb). The Bigeye thresher can grow to a length of 4.9 m (16 ft). And the Pelagic thresher is the smallest at 3 m (10 ft) long.

4. The thresher shark eats fish(such as bluefish, juvenile tuna and mackerel, squid and cuttlefish are the primary food items of the thresher sharks. They are known to follow large schools of fish into shallow waters. Crustaceans and the odd seabird are also taken.

5. Thresher sharks are solitary creatures which keep to themselves. In the Indian ocean they are separated by depth and space according to gender. When hunting fish the thresher sharks are known to “slap” the water, herding and stunning prey. Thresher sharks are one of the few shark species known to jump fully out of the water making turns like dolphins, this behaviour is called breaching.

6. Fertilization and embryonic development occur internally this ovoviviparous or live-bearing mode of reproduction results in a small litter (usually 2 to 4) of large well-developed pups, up to 150 cm at birth in thintail threshers. The young fish exhaust their yolk sacs while still inside the mother, at which time they begin feeding on the mother’s unfertilized eggs this is known as oophagy. Thresher sharks are slow to mature, males reaching sexual maturity between 7 and 13 years of age and females between 8 and 14 years in bigeye threshers. They may live for 20 years or more.

All of this info is from