Thresher Shark

Thresher Sharks are large mackerel sharks belonging to the family Alopiidae found in temperate and tropical oceans all around the world; the family contains 4 species all within the genus Alopias, 3 of which are extant with 1 extinct species.

Taxonomy
The genus and family name come from the Greek word alopex, which means fox. As a result of this, the common thresher shark, Alopias vulpinus, is also known as the fox shark. The common name comes from the distinctive, thresher-like tail or caudal fin of the sharks which can be as long as the body of the shark itself.

Species
All known thresher shark species are in the genus Alopias. The possible existence of a hitherto unrecognized fourth extant species was revealed in a 1995 allozyme analysis by Blaise Eitner. This species is apparently found in the eastern pacific region off Baja California, and has previously been misidentified as the bigeye thresher. So far, it is only known from muscle samples from a single specimen, and no aspect of its morphology has been documented.
 * Alopias pelagicus (pelagic thresher)
 * Alopias superciliosus (bigeye thresher)
 * Alopias sp. (undescribed)
 * Alopias vulpinus (common thresher)
 * †Alopias grandis