The Common Thresher Shark (Alopias vulpinus) is a shark whose tail fin has a greatly elongated upper lobe. This shark is a very strong swimmer and can even leap out of the water. The Common Thresher Shark is not an aggressive shark, but it can be provoked. The thresher's large tail can injure divers.

The Common Thresher Shark swims from the surface to a depth of about 1,150 feet (350 m). It lives in tropical and temperate waters, including the eastern and western Atlantic, the central Pacific, and the Indo-west Pacific. The Common Thresher is decreasing in numbers because of overfishing (it is hunted for meat and for its fins).

Anatomy: The Common Thresher has a countershaded body, dark blue-gray above and white underneath. It has small jaws, but can use its tail to corral and even kill fish. The first dorsal fin is much, much bigger than the second; the pectoral fins are curved. Like other mackerel sharks, it has an anal fin, 5 gill slits, 2 dorsal fins, no fin spines, the mouth behind the eyes, and no nictitating eyelids. The Common Thresher shark ranges from 16.5 to 20 ft (5 to 6 m) long.

Teeth and Diet: The Thresher eats squid and fish, corralling them with its elongated tail; it catches prey with its very sharp (but small) teeth.

Classification: Kingdom Animalia, Phylum Chordata, Class Chondrichthyes, Order Lamniformes, Family Alopias (Thresher sharks), Genus Alopias, Species vulpinus.