Facts about Thresher Shark

Thresher sharks derive their name from the unique and elongated tail fin, that they use as a defense, to 'thresh' or 'hit' their enemies. It is otherwise a very peace loving shark and normally keeps to itself, unless provoked by any enemy. They prefer open sea areas and dive nearly 500 meters into the sea. They are nocturnal and are mostly active at night only. They thrive in tropical and temperate waters and are mostly found in North America and Asia. Thresher sharks belong to the family 'Alopiidae' and their order is 'Lamniformes' (mackerel sharks). Alopias vulpinus, meaning long tailed thresher shark, is the biological name of this shark. In Greek, 'alopex' means fox and some researchers also call them as the fox sharks.

Body Features
The common thresher sharks or simply thresher sharks, have dark blue-gray body on the upper side and a white underbelly. They have very small jaws and sharp teeth. A big elongated upper lobe in the tail region helps in their easy identification in the sea. The mouth is behind the eyes. They have 2 dorsal fins, a large pectoral fin and 5 gill slots. They are 16.5 to 20 ft (nearly 5 to 6 m) long. The tail fin is usually one-third of the total body length!! They are very fast swimmers and even have the ability to leap out of water. Thresher sharks are one of the few sharks that jump fully out of the water, just like dolphins. The three species can be distinguished by the color of the dorsal surface of the body. The 'bigeye threshers' are brown, the 'pelagic threshers' are blue and the 'common thresher' sharks are dark green.

Diet
They feed on crustaceans, squid, octopuses and other small fishes. The strong tail helps the thresher sharks to kill their prey, often in a single blow.

Behavior
Threshers find solace in living alone and wandering in the depths of the ocean. They migrate within salt waters only, at different times of the year and often over large distances. Generally, they migrate in search of food and for reproduction. They are not considered dangerous to human life, though they may attack in self defense. There have been few instances where divers have been hit by its large caudal fin.

Reproduction
Thresher sharks are Ovoviviparous, that is, the egg remains in the mother's body and the offspring develops within it. The Ovoviviparous are not fed through the mother's body but are nourished by the egg yolk. The young ones exhaust their yolk sac and feed on the mother's unfertilized eggs, while still inside mother's body. The new born sharks are generally 110 to150 cm in length. At one time, a female usually produces 2-4 healthy pups. No particular season has been observed for their reproduction. Male thresher sharks reach maturity age in 10-15 years, whereas the females take more time to mature. Their life span is usually 20 years or more.

Thresher sharks - A Vulnerable Species
A lot of information about threshers, is still unknown. They have been declared, by the International Union for Conservation of Nature (IUCN), a vulnerable species since 2007. They are vulnerable to the point of extinction. They have been exploited on a large scale, for commercial purposes. Their meat, liver oil and fins are in great demand in the market. In America, South Africa, Baja (California) and Mexico they are also used for recreational purposes. It is rare to site a thresher shark diving in the ocean, so it has become a prized fish for underwater photographers and researchers.

Sharks evolved 100 million years before the dinosaurs did!! Humans evolved long after the dinosaurs, so sharks are actually one of the oldest inhabitants of this planet. They are a unique species and have survived tough environmental changes. It is of utmost importance that we preserve these unique sharks, such as the thresher sharks, and maintain the ecological balance of our Mother Earth.