Thresher Shark

Alopias Vulpinus

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Size, Weight, and Description

The largest known Thresher Sharks reach a length of more than 20ft and weigh 216 pounds. These sharks are slow growing sharks. They reach their maturity between 8 and 13 years old and live about 22 years. Thresher sharks have big eyes, a small mouth, large pectoral fins, first dorsal fin and pelvic fins. They have a small second dorsal fin (near their tail) and anal fins. Their most noticeable characteristic, as noted above, is that the top lobe of their tail is unusually long and whip-like. This tail may be used to herd and stun small fish.

Living Conditions

Although Thresher Sharks love open and deep waters, they are also found in shallow waters near coastal areas. They are generally not found deeper than 500 meters (1,640ft). They favor the Pacific and Indian Oceans, especially at the continental shelves of America and Asia.


Bony fish make up 97% of the thresher's diet. They feed mostly on small schooling fish such as menhaden, herring, Atlantic saury, sand lance, and mackerel. Bluefish and butterfish are the most common meal. They also feed on bonito and squid. Thresher sharks encircle schools of fish and then stun the prey with their tails. This is often done in groups and/or pairs. They have also been known to kill sea birds with their tails.

Swim Speed & Unique Traits

Thresher sharks swim at an average of 30 miles per hour. Whats unique about the thresher shark is obviously its long caudal fin. This long extension is used to herd fish and to stun them for the shark to prey on. Its other traits include large eyes and relatively small jaw and teeth.

Threat to humans?

This species poses very little threat to humans. The largest threat of injury is divers getting hit with the enormous tail. Attacks of any kind on humans are almost unheard of.


Threshers are VERY endangered. The abundance rate of their population has decreased 73% in the past few years. Due to recent population depletion, new laws are being enacted to help protect this species from upsetting the fragile balance of the marine ecosystem, especially since these sharks have a low reproductive rate as compared to other sharks.
Malapascua 2013 - Thresher Sharks