 thresher sharks are large lamniform sharks of the family alopiidae found in all temperate and tropical oceans of the world; the family contains four species, all within the genus alopias. ==taxonomy== the genus and family name derive from the greek word alopex, meaning fox. as a result, the long-tailed or common thresher shark, alopias vulpinus, is also known as the fox shark.http://www.britannica.com/ebchecked/topic/690940/fox-shark the common name is derived from a distinctive, thresher-like tail or caudal fin which can be as long as the body of the shark itself. ===species=== the three extant thresher shark species are all in the genus alopias. the possible existence of a hitherto unrecognized fourth species was revealed during the course of a 1995 allozyme analysis by blaise eitner. this species is apparently found in the eastern pacific off baja california, and has previously been misidentified as the bigeye thresher. so far, it is only known from muscle samples from one specimen, and no aspect of its morphology has been documented. * alopias pelagicus h. nakamura, 1935 (pelagic thresher) * alopias superciliosus r. t. lowe, 1841 (bigeye thresher) * alopias vulpinus bonnaterre, 1788 (common thresher) * alopias sp. eitner, 1995 ==phylogeny and evolution== {{cladogram|title=|caption=phylogeny of alopiidae{{cite journal |author=eitner, b. |title=systematics of the genus alopias (lamniformes: alopiidae) with evidence for the existence of an unrecognized species |journal=copeia |volume=1995 |issue=3 |year=1995 |pages=562â571 |doi=10.2307/14467
Alopiidae Commercial_fish Monogeneric_animal_families Ovoviviparous_fish Sport_fish