species shark family found temperate tropical oceans worldwide like sharks nearly half total length consists elongated upper lobe tail fin common comes enormous eyes placed shaped allow rotated upward species distinguished pair deep grooves head scientific derived large eyes adapted hunting low light conditions sharks conduct vertical migration staying deep water day moving surface waters night feed protect sensitive brain eyes temperature changes accompanying movements exchange system called organs species feeds mainly fish squid stunned whip like strikes long tail usually bearing litters pups embryos feed produced mother inside shark caught commercial fisheries range meat highly regarded skin fins liver oil valued assessed vulnerable taxonomy phylogeny british biologist scientifically describe papers published proceedings transactions society london given based description specimen caught eastern atlantic_ocean description subsequently overlooked researchers species known different names 1940s new specimens cuba florida prompted original scientific resurrected specific epithet latin super meaning meaning referring distinct lateral grooves eyes analysis conducted showed closest relative forms clade fossil remains dating found region japan distribution habitat virtually distribution western atlantic_ocean reported new_york florida bahamas cuba venezuela southern brazil eastern atlantic known portugal guinea mediterranean_sea western indian_ocean occurs south_africa madagascar pacific_ocean known southern japan taiwan northwestern australia new_zealand eastward hawaii southern california west analysis mitochondrial dna shown atlantic populations somewhat genetically usually found continental shelf open sea occasionally encountered shallow coastal waters occur surface temperatures tracked far temperature little known geographical movements individual documented moving new_york gulf_of_mexico straight line distance description eyes measure adults eye taller wide upper portion extend dorsal surface head allowing eyes orient upwards pair distinctive lateral grooves extend eyes gill slits giving helmet appearance snout moderately long furrows corners mouth teeth moderately large single narrow teeth upper jaw teeth lower jaw shapes similar jaws large small dermal denticles smaller ones numerous interspersed larger ones smaller denticles point half body length taken long upper lobe caudal fin broader large pectoral fins curved anterior margin broad tips dorsal fin placed sharks free rear tip located pelvic fins coloration deep metallic violet brown white color rapidly fades dull gray death long weigh largest known measured long weighed caught near new_zealand february biology ecology size upward orientation eyes adapted search prey dim light species handful shark species conducts vertical migration spending daytime deeper water beneath temperature ranges ascending water deep nighttime migration likely relates finding prey night avoiding predators day sharks daytime swimming patterns usually steady night pattern slow rapid likely preyed larger sharks marine mammals known parasites include sea seen attached near shark appears ecological competitor blue shark numbers species negatively occurs given location feeding larger teeth feeds wider variety prey known food items include schooling forage fish herring benthic fishes larger fishes small squid possibly crab likely use long tails prey prior capture found hooked tails bait fish shape eye vision upward direction better aim strikes mediterranean strongly associated schools frigate suggesting sharks follow concentrations prey place place said uses long tail birds life history like sharks bear litters pups rarely litter size defined breeding season adult females pregnant year apparent time gestation period unknown developing initially yolk sac later exhibit consume eggs produced mother possibly fluid evidence sibling sand tiger shark embryos similar appearance adults larger heads eyes covered thin layer prevents wall embryo sharp dermal denticles observed young sharks young measure long birth males mature length age years females mature length age years maximum lifespan species believed years male years female female estimated produce young entire life conflicting evidence warm bodied like common study carey swimming muscles needle reported finding temperature elevation compared ambient environment examination conducted found possesses red muscles responsible generating heat common muscles arranged strips flanks beneath skin opposed near core body blood vessel exchange system trunk limit loss heat water based differences authors questioned earlier measurements concluded unlikely maintains elevated body temperature possess highly developed system brain eyes thought function sensitive organs temperature changes shark daily water column human interactions shark rarely encountered divers underwater poses danger species taken fisheries operated countries including united_states japan spain brazil mexico constitutes shark catch comprises catch cuba attracted night sticks chemical lights significant fisheries land metric tons annually meat marketed fresh smoked dried highly regarded texture skin leather products liver oil fins shark fin soup waters united_states species considered occasionally caught shark nets beaches south_africa species listed game fish pursued recreational united_states south_africa new_zealand highly susceptible exploitation low lifetime shark species assessed vulnerable
Bigeye thresher