Common thresher

The common thresher (Alopias vulpinus), also known as Atlantic thresher, is the largest <a href="/facts/Species/oDg6b96r">species</a> of <a href="/facts/Thresher_shark/WT5Rcqy0">thresher shark</a>, <a href="/facts/Family_(biology)/qTrn6E8E">family</a> Alopiidae, reaching some 6 m (20 ft) in length. About half of its length consists of the elongated upper lobe of its <a href="/facts/Caudal_fin/kS10PMPf">caudal fin</a>. With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles (and has often been confused with) the <a href="/facts/Pelagic_thresher/qU952KKt">pelagic thresher</a> (A. pelagicus). It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its <a href="/facts/Pectoral_fin/kS10PMPf">pectoral fins</a>. The common thresher is distributed worldwide in <a href="/facts/Tropical/Iv1es8Ih">tropical</a> and <a href="/facts/Temperate/6WPypCzC">temperate</a> waters, though it prefers cooler temperatures. It can be found both close to shore and in the open ocean, from the surface to a depth of 550 m (1,800 ft). It is seasonally <a href="/facts/Fish_migration/obNpLAUD">migratory</a> and spends summers at lower <a href="/facts/Latitude/IBYqkjhU">latitudes</a>.
The long tail of the common thresher, the source of many fanciful tales through history, is used in a whip-like fashion to deliver incapacitating blows to its prey. This species feeds mainly on small <a href="/facts/Shoaling_and_schooling/vFAw9F75">schooling</a> <a href="/facts/Forage_fish/RJUKYJPb">forage fishes</a> such as <a href="/facts/Herring/QH12ADpV">herrings</a> and <a href="/facts/Anchovy/b1HycvUw">anchovies</a>. It is a fast, strong swimmer that has been known to leap clear of the water, and possesses <a href="/facts/Endothermy/qs3DIGHx">physiological adaptations</a> that allow it to maintain an internal body temperature warmer than that of the surrounding sea water. The common thresher has an <a href="/facts/Aplacental_viviparous/sPk5JLTN">aplacental viviparous</a> mode of reproduction, with <a href="/facts/Oophagy/DlQmXnUW">oophagous</a> <a href="/facts/Embryo/9QHnLVLN">embryos</a> that feed on undeveloped eggs <a href="/facts/Ovulation/0K3MLdAv">ovulated</a> by their mother. Females typically give birth to four pups at a time, following a <a href="/facts/Gestation_period/WgfFSV9R">gestation period</a> of nine months.
Despite its size, the common thresher is minimally dangerous to humans due to its relatively small teeth and timid disposition. It is highly valued by <a href="/facts/Commercial_fishing/8XF3oLTc">commercial fishers</a> for its meat, <a href="/facts/Shark_fin_soup/ftEvM1Ed">fins</a>, hide, and <a href="/facts/Shark_liver_oil/GTNuMkBF">liver oil</a>; large numbers are taken by <a href="/facts/Longline_fishing/YHpRGXaL">longline</a> and <a href="/facts/Gillnet/kboN0ltQ">gillnet</a> fisheries throughout its <a href="/facts/Range_(biology)/SAI9lJq9">range</a>. This shark is also esteemed by <a href="/facts/Recreational_fishing/TxSCu0X3">recreational anglers</a> for the exceptional fight it offers on hook-and-line. The common thresher has a low rate of reproduction and cannot withstand heavy fishing pressure for long, a case in point being the rapid collapse of the thresher shark fishery off <a href="/facts/California/zLW2vdQJ">California</a> in the 1980s. With commercial exploitation increasing in many parts of the world, the <a href="/facts/International_Union_for_Conservation_of_Nature/QwV8JXup">International Union for Conservation of Nature</a> has assessed this species as <a href="/facts/Vulnerable_species/79WNk4Gj">vulnerable</a>.

Common thresher open-in-new

Common thresher