species family common northeastern atlantic_ocean iceland including mediterranean_sea typically found continental slope depths near muddy bottoms youngest sharks generally inhabit shallower water older juveniles adults slim bodied species characterized black interior mouth pattern pale edged brownish tail prominent saw toothed crest enlarged dermal denticles upper edge caudal fin reaches lengths sharks atlantic growing larger mediterranean slow swimming active wide variety crustaceans cephalopods fishes visual systems adept tracking moving prey species females producing egg cases year abundance forms substantial commercial fisheries range low economic value usually discarded largest sharks marketed meat leather listed species concern indication numbers declined despite fishing pressure taxonomy phylogeny constantine briefly described con referenced distinctive black interior mouth specific epithet derived type specimen designated species called black phylogenetic analysis included species based mitochondrial nuclear dna found forms clade apart clade oldest documented fossils come northern date distribution habitat widely distributed northeastern atlantic_ocean southwestern iceland trondheim norway southward including british isles azores northern portion occurs mediterranean_sea save northern waters adriatic seas absent black_sea species primarily inhabits continental slope depths documented water shallow norway deep eastern mediterranean depths common vary regions example portugal eastern mediterranean water temperature appear important factor determining distribution species found near favors muddy habitat little evidence segregation sex number studies northern western mediterranean reported adults occur deeper juveniles studies found pattern possible areas waters southern france offer habitat suitable sharks ages explanation scientific support adults common intermediate depths young sharks restricted shallower water adults juveniles found deeper water true age depth inconsistencies observed previous research resulted incomplete depth sampling description reported maximum lengths attained varies atlantic sharks mediterranean sharks length record dubious females attain larger ultimate size males maximum weight record species slender firm body long pointed snout comprising roughly total length anterior rim bears large triangular divides openings eyes horizontally oval equipped rudimentary membranes protective beneath eye subtle ridge small mouth forms short wide arch bears moderately long furrows corners upper lower jaws contain tooth rows respectively tooth small narrow central flanked smaller pairs gill slits fifth pair pectoral fin bases dorsal fins roughly equal size placed far body originates pelvic fin bases second anal fin base pectoral fins large pelvic fins small low angular margins anal fin larger dorsal fin base measures total length greatly exceeds distance pelvic anal fins dorsal fins caudal compressed end anal fin close caudal fin caudal fin comprises quarter total length upper lobe low ventral notch near tip lower lobe indistinct skin thick covered dermal denticles prominent row enlarged denticles resembling saw teeth upper edge caudal fin body grayish brown dark rounded spots run tail marking highlighted paler border underside white tips dorsal caudal fins inside mouth black biology ecology range abundant sharks upper middle continental slope nomadic nature found groups relatively slow shark strong like body cruises sea floor taking advantage ground effect reduction drag wing close ground save energy seen resting known predators include shark european flying squid parasites documented species include feeding active predator feeds dwelling free swimming organisms diet dominated bony fishes including cephalopods significant prey species generally reflect available environment example southern france juveniles consume greater variety crustaceans adults including smaller types adults favor relatively large fish prey known sharks rays smaller members species importance prey ages differs regions found contain pieces animals large single shark suggesting attack groups documented including human refuse foraging swings head employ senses effectively likely relies mainly vision find food smell sharks visual greatest median horizontal plane lens cone cells eyes large allowing smaller farther objects background rod cells eyes sensitive emitted exhibited organisms hunts high number evenly arranged spatial resolution best suited fast moving prey life history unlike members genus exhibits multiple egg mature simultaneously females contain developing eggs typical number eggs laid annually female estimated increasing female size right functional mature females egg case shaped bears slight lateral margins anterior end squared pair horns corners posterior end rounded surface case somewhat translucent smooth glossy case golden brown color laid dark brown sea water egg cases produced atlantic sharks measure long produced mediterranean sharks tend smaller long larger females produce slightly larger egg cases mating egg laying proceeds year round reproductive activity highest winter summer studies found seasonal pattern eggs deposited muddy relatively shallow water maturation size varies geographical regions generally larger atlantic mediterranean lengths maturity males females variously reported respectively atlantic respectively mediterranean human interactions harmless humans little economic value caught incidentally large numbers commercial fisheries particular commonly sharks targeting operating portugal mediterranean captured sharks discarded probably heavy mortality fisheries portugal italy retain utilize small largest individuals human consumption fresh dried leather fishing fleet reported landing northeastern atlantic shark increasingly targeted following decline shark species sicily southern portugal southern adriatic seas captured immature suggesting negative impact fishing pressure species remains extremely abundant number areas survey fishery data shown evidence overall population decline wide range depths occupies likely afford protection fishing particularly given ban deeper mediterranean listed concern waters fishing species managed sharks
Blackmouth catshark