This is the largest variety of thresher shark in the world, growing up to 20 feet (6 m) from its nose to the end of its extremely long caudal (tail) fin. This feature is the shark’s most prominent attribute, but it also performs an important function as the shark can use it like a whip, inflicting painful blows to predators and prey alike. Aside from the unique tail, the shark can be identified by its streamlined body and stubby snout. It is generally gray or bluish-gray in color with a white belly band that extends over the top of the pectoral fins. Although a large shark, its teeth are comparatively small and suited for catching fish. The thresher shark is a docile species and presents little threat to human beings. Conversely, the shark is highly prized by many sport fishermen as it is notorious for the strong fight it will put up when on a fishing line.
The Common Thresher Shark can generally be found in coastal waters near the surface where schools of fish are plentiful. They are found all along the west coast of the United States and as far south as Mexico. There is another subspecies called the Pelagic Thresher (Alopias pelagicus) which is similar in appearance but stays mostly in the open ocean.
A slow reproduction cycle combined with overfishing may be what caused a rapid drop in its population during the 1980s. Restrictions on over-harvesting the thresher have helped to increase its numbers in recent years, but it is still considered a “vulnerable” species.