shark shark seal shark species shark family species genus found sporadically world usually close sea floor depths sizable oil filled liver maintain neutral shark able cruise slowly water little energy shark slender body short blunt snout large eyes thick lips teeth highly differentiated upper lower jaws upper teeth small narrow lower teeth large triangular typical length armed large teeth strong bite shark powerful solitary predator takes different types prey ranging bony fishes sharks rays cephalopods crustaceans worms possibly takes bites animals larger similar smaller relative shark shark viviparous gives birth young shark commercially meat skin liver oil primarily portugal japan fishery targeting species existed azores 1970s 1990s collapsed falling liver oil prices rapid azores stock cited example deep sea sharks human exploitation low reproductive rate species renders susceptible coupled known population declines led assessed taxonomy shark originally described french naturalist des nature type specimen cap lost species later placed genus came authorities dispute grounds prefer use available genus genus derived greek meaning torch specific epithet comes french shark additional common names shark include black shark charlie phylogeny evolution studies consistently found closest relatives shark sharks share skeletal muscular similarities believed diverged shortly transition cretaceous periods larger radiation sharks deep sea relatively shallower habitats oldest fossil teeth definitively belong shark date recovered stage deposits new_zealand fossil teeth dating ages discovered europe ussr japan western india fossil material recognized belonging species historically described multitude different names description shark moderately elongated body short rounded snout eyes large lips thick fringes modified tooth rows upper jaw tooth rows lower jaw upper teeth small spike shaped curving slightly corners mouth lower teeth large knife shaped bases form continuous cutting surface dorsal fin slightly smaller shorter based second spines dorsal fin originates free rear tip pectoral fins second originates middle pelvic fin bases pectoral fins short rounded caudal fin prominent upper lobe developed notch near tip barely present lower lobe form arrangement fins similar portuguese species distinguished lack fin spines dermal denticles small flat single horizontal ridge ending point coloration uniform dark brown gray faint black spots fins white translucent trailing edges tip caudal fin black long shark partial lacking pigment body caught unlike previous case portuguese abnormal coloration individual diminished ability capture prey sharks long weigh maximum reported length possibly distribution habitat shark range tropical warm temperature waters consisting number widely separated populations likely little interchange shark reported eastern pacific northern indian oceans northern atlantic occurs northern gulf_of_mexico north_sea including british isles western central mediterranean_sea azores indian_ocean found south_africa pacific occurs japan java australia new_zealand single record species southern atlantic southern brazil offshore species shark common depth captured surface deep azores shark sex females common depth males common shark inhabits outer continental shelves upper continental slopes found oceanic islands member family tends found close sea floor opposed middle water column occasion captured biology ecology relatively common occurs sharks usually solitary nature form small groups slow swimmer large liver filled dense water allowing maintain neutral little effort studies coast north_africa found males females respectively sex ratio observed south_africa reflect sampling bias shark preyed larger fishes sharks sperm parasite data species limited examination sharks caught ireland found stomach identified powerful versatile predator short robust jaws shark enormously strong bite feeds mainly bony fishes including snake sea takes wide variety animals including smaller sharks squid octopus crustaceans shrimp worms like related shark shark capable flesh animals larger including sharks presence fast swimming fishes diet suggests shark means capturing faster prey mediterranean bony fishes important food year round second important prey sharks winter spring crustaceans summer cephalopods fall captured males likely females unknown reasons reproduction shark viviparous embryos hatching inside sustained term yolk adult females functional functional divided compartments mediterranean breeding occurs year peaks spring fall females year rest litter size increasing female size young born length varying geographic location possible gestation period years males mature sexually length females length relationship individual size birth size maturity maximum size human interactions shark inhabits depths great danger humans upper teeth found lodged underwater cables species long history human exploitation meat consumed eastern atlantic japan processed liver oil utilized portugal japan south_africa skin type useful making furniture jewelry favored manufacture spanish polished leather shark commercial value western atlantic continuing expansion commercial fisheries deep sea raised concerns vulnerability shark species sharks slow growth reproductive rates exemplified rapid stock collapse azores shark fishery targeted fishery began early 1970s production liver oil early 1980s fishing fleet enlarged addition industrial vessels equipped resulting fishery peak tons landed shark catches declined tons annually drop global price liver oil led fishery end decade population assessment suggested northeastern atlantic stock fallen pre exploitation fisheries operating portugal japan responsible commercial landings shark generally hook line portugal reported shark tons tons areas northeastern atlantic shark rare reported catches likely species caught mixed species fisheries operating deep water west british isles surveys suggest shark numbers declined 1970s mediterranean shark caught incidentally fisheries generally discarded alive unable return deep water survive catches australian south east fishery increasing following regulations mercury content species included australian fishery new_zealand shark catches peaked assessed shark worldwide vulnerable northeastern atlantic light documented population declines
Kitefin shark