argonauta argo , also known as the greater argonaut , is a species of pelagic octopus belonging to the genus argonauta .

the female of the species , like all argonauts , creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell , hence the name paper nautilus .

the chinese name for this species translates as " white sea-horse 's nest " .

a. argo was the first argonaut species to be described and is consequently the type species of the genus .

a. argo is the largest species in the genus and also produces the largest eggcase .

live animals have a characteristic blue sheen on the first arm pair and around the eyes .

the eggcase is characterised by two rows of small , sharp tubercles running along a narrow keel , smooth ribs across the walls of the shell , and a thickening along the shell aperture , which forms distinct protrusions or ' horns ' on either side .

argonauta cygnus monterosato , 1889 was described based on a shell which lacked these protrusions , although it is now considered a junior synonym of a. argo .

the greatest recorded size of an a. argo eggcase is 300.0 mm .

a. argo is cosmopolitan , occurring in tropical and subtropical waters worldwide .

a dwarf form exists in the mediterranean sea , which was described as argonauta argo mediterranea monterosato , 1914 , although this taxon is now regarded as invalid .

a. argo is thought to feed primarily on pelagic molluscs .

the species is preyed on by numerous predators .

it has been reported in the stomach contents of alepisaurus ferox from the south-western pacific .

males of this species reach sexual maturity at a mantle length ( ml ) of 8 mm .

females mature at about double the size of argonauta bottgeri and argonauta hians .

they begin to secrete an eggcase at 6.5 – 7 mm ml .

eggs are usually laid when females reach 14 – 15 mm ml , although the size at which this takes place differs across the animal 's range .

a small a. argo residing in an 88 mm long eggcase was estimated to be carrying 48,800 embryos .

females grow to 100 mm ml , while males do not exceed 20 mm ml .

in the open ocean , a. argo has been observed attached to jellyfish .

this behaviour has been known for a long time , although little was understood about the relationship prior to the work of heeger et al. in 1992 .

in " predation on jellyfish by the cephalopod argonauta argo " , heeger et al. describe their observations of a female a. argo found atop a host jellyfish .

the argonaut was seen holding on to the aboral ( exumbrellar ) surface of the jellyfish using its lateral and ventral arms .

the authors found that about half of the animal 's aboral surface was damaged and large pieces of mesoglea were missing , presumably removed by the argonaut .

additionally , two holes , apparently bite marks , were found in the center of this area with channels leading from these holes into the gastral cavity of the jellyfish .

the argonaut presumably used these channels to suck food particles from the gastral cavity .

heeger et al. suggested that " the association provided shelter or camouflage for the argonaut " .

observations of captive a. argo females suggest that the expanded webs of the dorsal arms may aid the animal in feeding .

mark norman mentions that " when food was touched against the spread webs , an arm shot out of the shell in a sweeping action , grabbing the prey " .

it is speculated that argonauts do not actively hunt , but employ this method to catch animals that bump into them in the open ocean .

a. argo is occasionally involved in mass strandings along the south african and southern australian coastlines .

the strandings are seasonal and generally occur between april and august , towards the end of the animals ' spawning season .

a damaged beak of a female a. argo ( ml = 40.0 mm ; caught at 20 ° 56 ′ n 175 ° 33 ′ w ) , measuring 4.30 mm in hood length and 7.80 mm in crest length , is mentioned in a handbook for the identification of cephalopod beaks .

the type specimen of a. argo was collected in the mediterranean sea and is deposited at the linnean society of london .

argonauta argo

forma argonauta argo f . agglutinans martens , 1867 accepted as argonauta argo linnaeus , 1758
forma argonauta argo f . aurita martens , 1867 accepted as argonauta argo linnaeus , 1758
forma argonauta argo f . mediterranea monterosato , 1914 accepted as argonauta argo linnaeus , 1758
forma argonauta argo f . obtusangula martens , 1867 accepted as argonauta argo linnaeus , 1758
variety argonauta argo var . americana dall , 1889 accepted as argonauta argo linnaeus , 1758
figure . two views of argonauta argo atop the jellyfish , phyllorhiza punctata . photographs copyright © , thomas heeger , university of san carlos , philippines .
figure . hectocotylus of argonauta argo . top - oral view . middle - aboral view . bottom - side view . drawings from naef , 1921 - 3 .
figure . left - lateral view of an argonauta argo shell , hawaii . photograph by r . young ) . right - a collection of argonauta nodosa shells from a swarm that washed ashore , australia . photograph by mark norman .
to cite this page : virden , t . 1999 .
argonauta argo
( on - line ) , animal diversity web . accessed july 09 , 2018 at urltoken
heeger , t . , u . piatkowski and h . möller . 1992 . predation on jellyfish by the cephalopod argonauta argo . marine ecology progress series 88 : 293 - 296 .
figure . view of a portion of the radula of a . argo . drawing from naef ( 1921 - 1923 ) .
okutani , t . and t . kawaguchi . 1983 . a mass occurrence of argonauta argo ( cephalopoda : octopoda ) along the coast of shimane prefecture , western japan sea . venus 41 : 281 - 290 .
figure . side - oblique views of an argonauta argo , photographed in a ship - board aquarium . left - arm i web expanded over shell . right - arm i web retracted . photographs by m . vecchione .
( of argonauta argo f . obtusangula martens , 1867 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta argo f . aurita martens , 1867 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta argo f . agglutinans martens , 1867 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta argo var . americana dall , 1889 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta argo f . mediterranea monterosato , 1914 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta ferussaci monterosato , 1914 ) monterosato t . a . ( di ) ( 1914 ( 30 giugno ) ) . sur les argonauta de la méditerranée . journal de conchyliologie 61 ( 4 ) : 385 - 390 , tabs . x - x3 [ details ]
( of argonauta corrugata humphrey , 1797 ) check list of european marine mollusca ( clemam ) . , available online at urltoken [ details ]
( of argonauta haustrum wood , 1811 ) check list of european marine mollusca ( clemam ) . , available online at urltoken [ details ]
( of argonauta papyria conrad , 1854 ) check list of european marine mollusca ( clemam ) . , available online at urltoken [ details ]
( of argonauta monterosatoi coen , 1915 ) coen g . ( 1915 ) . delle forme adriatiche di argonauta ed in particolare dell ' a . monterosatoi n . sp . . annali del museo civico di storia naturale di genova ( 3 ) 6 ( 46 ) : 261 - 275 , pl . 5 [ details ]
figure . lateral view of a juvenile female ( 6 . 5 mm ml ) argonauta hians showing the web on arms i , equatorial south atlantic . drawing from chun , 1910 .
figure . side and ventral views of the funnel and mantle locking - apparatus of argonauta hians , juvenile male , 5 . 0 mm ml , equatorial south atlantic . drawing from chun , 1910 .
figures . lateral and oral views of male argonauts . left , center - a 5 mm ml , apparently immature , male argonauta hians from the equatorial south atlantic . drawings from chun , 1910 . in oral view the male looks like a 7 - arm octopus . right - a male argonauta nodosa , off australia , with the hectocotylus in a much larger sac is apparently mature . photograph by mandy reid ; provided by mark norman .
( of argonauta minor risso , 1854 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta ferussaci monterosato , 1914 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta monterosatoi monterosato , 1914 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta cygnus monterosato , 1889 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta pacificus dall , 1871 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta corrugatus humphrey , 1797 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta papyraceus röding , 1798 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta sulcatus lamarck , 1801 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta grandiformis perry , 1811 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta haustrum dillwyn , 1817 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta monterosatoi coen , 1915 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta dispar conrad , 1854 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta compressus blainville , 1826 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta papyrius conrad , 1854 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta naviformis conrad , 1854 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta bulleri kirk , 1886 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
( of argonauta sebae monterosato , 1914 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
banas , p . t . , d . e . smith and d . c . biggs . 1982 . an association between a pelagic octopod , argonauta sp . linnaeus 1758 , and aggregate salps . fish . bull . u . s . 80 : 648 - 650 .
embryonic development begins in the oviducts . older embryos are attached to the inner region of the shell where they are brooded . the elongate egg stalks ( extensions of the egg chorion ) are woven together and attached to the shell apex on its inner surface . a female a . argo with a shell length of 88 mm was estimated to be carrying 48 , 800 embryos ( okutani and kawaguchi , 1983 ) . the eggs are very small ( 0 . 6 - 1 . 0 mm ) . spawning is intermittent , and the brooding embryos can be seen to be in different stages of development .
figure . side view of argonauta sp . , showing the expansion of the web ( web presence indicated by their chromatophores ) of the first arm , past the horn of the shell and over most of the shell surface , gulf of aqaba , red sea . photograph of living argonaut by shai enbinder ; provided by nadav shashar .
( of argonauta cygnus monterosato , 1889 ) monterosato t . a . ( di ) ( 1889 ( 1 gennaio ) ) . coquilles marines marocaines . journal de conchyliologie 37 ( 1 ) : 20 - 40 ; 37 ( 2 ) : 112 - 121 . , available online at urltoken page ( s ) : 120 [ details ]
( of argonauta cygnus monterosato , 1889 ) gofas , s . ; afonso , j . p . ; brandào , m . ( ed . ) . ( s . a . ) . conchas e moluscos de angola = coquillages et mollusques d ' angola . [ shells and molluscs of angola ] . universidade agostinho / elf aquitaine angola : angola . 140 pp . ( look up in imis ) [ details ]
( of argonauta minor risso , 1854 ) adam , w . ( 1942 ) . notes sur les céphalopodes : 21 . a propos d ' une publication peu connue de a . risso 1854 [ notes on the cephalopods : 21 . on a hardly known publication from a . risso 1854 ] . bull . mus . royal d ' hist . nat . belg . / med . kon . natuurhist . mus . belg . 18 ( 25 ) : 1 - 36 ( look up in imis ) [ details ]
argonauts are pelagic in tropical and subtropical surface waters of all oceans and seas . sometimes they are found in large swarms , but only rarely are they encountered nearshore . in the open ocean they are commonly found attached to jellyfish ( david , 1965 ) . while this unusual association between argonauta spp . and jellyfish has long been known ( kramp , 1956 ; david , 1965 ) it was uninvestigated prior to the work of heeger et al . ( 1992 ) . the latter authors describe argonauta astride the aboral ( = exumbrellar ) surface of a swimming jellyfish that it held with its lateral and ventral arms . upon examination of the jellyfish they found about half of its aboral surface was damaged and large pieces of mesoglea were missing . two holes , apparently bite marks were found in the center of this area and channels led from these holes into the gastral cavity of the jellyfish . they presumed the octopod used these channels to suck particles ( food ) from the gastral cavity . they also suggest that the association provided shelter or camouflage for the argonaut .
the female lives in a thin , calcareous , laterally compressed shell secreted by its dorsal arms . the shell is paper - thin and the animal is commonly called the
paper nautilus .
the latter part of the name comes from similarly - shaped shell of nautilus . the shell of the pearly nautilus , however , is the true cephalopod shell ( i . e . , the homologue of the molluscan shell ) and not a unique evolutionary innovation like the
shell
of argonauta ( naef , 1921 - 23 ) .
( of argonauta cygnus monterosato , 1889 ) finn j . k . ( 2014 ) . family argonautidae . pp . 228 - 237 , in p . jereb , c . f . e . roper , m . d . norman & j . k . finn eds . cephalopods of the world . an annotated and illustrated catalogue of cephalopod species known to date . volume 3 . octopods and vampire squids . fao species catalogue for fishery purposes [ rome , fao ] . 4 ( 3 ) : 353 pp . 11 pls . page ( s ) : 230 [ details ]
( of argonauta pacificus dall , 1871 ) finn j . k . ( 2014 ) . family argonautidae . pp . 228 - 237 , in p . jereb , c . f . e . roper , m . d . norman & j . k . finn eds . cephalopods of the world . an annotated and illustrated catalogue of cephalopod species known to date . volume 3 . octopods and vampire squids . fao species catalogue for fishery purposes [ rome , fao ] . 4 ( 3 ) : 353 pp . 11 pls . page ( s ) : 230 [ details ]
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thank you for taking the time to provide feedback on the iucn red list of threatened species website , we are grateful for your input .
have been described . a full list is given by mangold , vecchione and young ( 2008 ) . taxonomic work on this genus is required , but
is undoubtedly a good species and is the type species of the genus . we treat
has been assessed as least concern because , although little is known about this species , its wide distribution , oceanic lifestyle and low interest to fisheries suggest that it is not threatened .
this species is found in surface tropical and subtropical waters of the world ' s oceans . in the atlantic , it extends north to cape cod in the west and portugal in the east and south to brazil in the west and southern africa in the east . it also occurs in the mediterranean sea . in the pacific , its northern limits appear to be california in the east and southern hokkaido in the west . it extends southwards to subtropical waters around australia and new zealand . it is found throughout the indo - west pacific ( nesis 1987 , norman 2000 ) .
albania ; algeria ; american samoa ; angola ; anguilla ; antigua and barbuda ; aruba ; australia ; bahamas ; bangladesh ; barbados ; belize ; benin ; bermuda ; bonaire , sint eustatius and saba ; bosnia and herzegovina ; brazil ; british indian ocean territory ; brunei darussalam ; cambodia ; cameroon ; cape verde ; cayman islands ; china ; christmas island ; cocos ( keeling ) islands ; colombia ; comoros ; congo ; congo , the democratic republic of the ; cook islands ; costa rica ; côte d ' ivoire ; croatia ; cuba ; curaçao ; disputed territory ; djibouti ; dominica ; dominican republic ; ecuador ; egypt ; el salvador ; equatorial guinea ; eritrea ; fiji ; french guiana ; french polynesia ; gabon ; gambia ; ghana ; gibraltar ; greece ; grenada ; guadeloupe ; guam ; guatemala ; guinea ; guinea - bissau ; guyana ; haiti ; honduras ; hong kong ; india ; indonesia ; iran , islamic republic of ; iraq ; italy ; jamaica ; japan ; kenya ; kiribati ; korea , democratic people ' s republic of ; korea , republic of ; kuwait ; liberia ; libya ; macao ; madagascar ; malaysia ; maldives ; malta ; marshall islands ; martinique ; mauritius ; mayotte ; mexico ; micronesia , federated states of ; monaco ; montenegro ; montserrat ; morocco ; mozambique ; myanmar ; namibia ; nauru ; new caledonia ; new zealand ; nicaragua ; nigeria ; niue ; norfolk island ; northern mariana islands ; oman ; pakistan ; palau ; panama ; papua new guinea ; peru ; philippines ; pitcairn ; portugal ; puerto rico ; qatar ; réunion ; russian federation ; saint barthélemy ; saint helena , ascension and tristan da cunha ; saint kitts and nevis ; saint lucia ; saint martin ( french part ) ; saint vincent and the grenadines ; samoa ; san marino ; sao tomé and principe ; saudi arabia ; senegal ; seychelles ; sierra leone ; singapore ; sint maarten ( dutch part ) ; solomon islands ; somalia ; south africa ; spain ; sri lanka ; sudan ; suriname ; taiwan , province of china ; tanzania , united republic of ; thailand ; timor - leste ; togo ; tokelau ; tonga ; trinidad and tobago ; tunisia ; turks and caicos islands ; tuvalu ; united arab emirates ; united states ; united states minor outlying islands ; vanuatu ; venezuela , bolivarian republic of ; viet nam ; virgin islands , british ; virgin islands , u . s . ; wallis and futuna ; western sahara ; yemen
female argonauts secrete a shell using glands on their dorsal arms into which they lay their eggs . they produce the shell early in life ( before maturation ) and use it as a home . males are dwarf and have been reported living within salps ( banas et al . 1982 ) . they have a modified third arm which detaches during mating and carries the spermatophores to the females . female argonauts are often found associated with jellyfish , which they use as a source of food and possibly as camouflage ( heeger et al . 1992 ) . eggs are small ( 50 , 000 ) and are brooded in the shell until they hatch ( laptikhovsky and salman 2003 ) . up to five developmental stages can be present in one shell , which is neutrally buoyant due to the female trapping air at the surface ( jereb et al . 2014 ) . the species is assumed to be semelparous and likely has a lifespan of around one year as is common for other cephalopod species . females probably spawn continuously releasing a batch of around 2 , 000 - 4 , 000 eggs per day over a period of a month or more ( laptikhovsky and salman 2003 ) .
the shells are of interest to the shell trade and the flesh is edible . this species is of limited interest to fisheries but is reported occasionally in indian , japanese and taiwanese ( jereb et al . 2014 ) markets , occasionally with landings of several hundred kilograms ( de bruin et al . 1995 ) . jereb et al . ( 2014 ) state that between the 17th of june and 3rd of july 1982 , around 6 , 300 females were caught in the sea of japan .
there is a potential threat from the shell trade , but mostly trade appears to be of shells that wash up on shores so this cannot be considered a current threat .
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yes , it ' s a cephalopod ! this squid and other cephalopods are featured in the cephalopod pages maintained at the national museum of natural history , department of invertebrate zoology ! see the following links for more information on cephalopods .
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the list of species featured in the videos , arranged as a taxonomic list , only relevant taxa included .
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expedition journals from the search for the giant squid off new zealand , 1999 .
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katharina m . mangold ( 1922 - 2003 ) , michael vecchione , and richard e . young
the family contains at least four species ( nesis , 1982 / 7 ) .
argonauts are muscular , pelagic octopods . females secrete a thin calcareous
shell
in which they reside . shells may reach a length of 30 cm ( nesis , 1982 ) . the dorsal arms of females are modified with large , flag - like membranes that expand over the shell and are responsible for the secretion of the shell . eyes are very large and webs very small . the mantle - funnel locking apparatus consists of knob - like cartilages ( mantle ) and matching depressions ( funnel ) . males are dwarfs .
females with distal flag - like expansion of the web of the dorsal arms that contain shell - secreting glands .
presence of external
shell
in females secreted by the dorsal arms . the true molluscan shell ( i . e . , stylets in most incirrates ) is absent .
a list of all nominal genera and species in the argonautidae can be found here . the list includes the current status and type species of all genera , and the current status , type repository and type locality of all species and all pertinent references .
an unusual feature of argonauts is the secreted shell that functions as a brood chamber . the
shell
is not homologous with the true molluscan shell as evidenced by its unique site of formation : the dorsal arms of the female rather than the internal shell sac as in other coleoids . naef ( 1921 / 3 ) noted the remarkable resemblance of the argonaut shell to the shells of some of the abundant cretaceous ammonoids and suggested that the argonaut shell evolved in the following way : ancestral argonauts occupied empty ammonoid shells during the late cretaceous . [ occupancy of molluscan shells by octopodids is common in the present day . ] the octopod evolved glandular structures on the arms to repair the shell of the ammonoids after the latter had become extinct at the end of the cretaceous . eventually , the ammonoid shell was completely replaced by a secreted structure whose shape had been evolutionarily molded by the ammonoid shell . however , as pointed out by young et al . ( 1998 ) , a gap of about 40 million years exists between extinction of ammonoids and the earliest fossil record of an argonaut , and they suggest that the mold for the shell was from some other type of mollusc and that the resemblance to ammonoids is coincidental . the origin of the argonaut shell is a challenging problem and has important implications for understanding the relationships amoung groups of the argonautoidea ( young , et al . , 1998 ) .
the male argonaut is a dwarf , about 10 % of the length of the female . the entire third right arm is hectocotylized and carried in a special sac . at mating , the hectocotylus , which carries one large spermatophore , breaks out of its sac and then from the male body . the free hectocotylus invades , or is deposited in , the female ' s mantle cavity , where it remains viable and active for some time . the hectocotylus was first described as a worm parasitic on the female ( delle chiaje , 1825 ) .
the argonaut paralarva has a distinctive appearance as seen in the photo . the arms are very short and equal in length and are surrounded in their proximal half by a membranous collar or cuff ( barely recognizable in the photograph ) formed by the interbrachial membrane . the latter feature is found also in tremoctopus hatchlings . the life - span is unknown .
- ventrolateral view captured in a plankton tow , hawaii . photograph by r . young .
- side view . drawing from naef ( 1921 - 230 . note the lock and pit of the funnel / mantle locking - apparatus at the bottom of the photograph and drawing .
males have been reported living within salps ( banas et al . , 1982 ) .
chun , c . 1910 . die cephalopoden . oegopsida . wissenschaftliche ergebnisse der deutschen tiefsee expedition auf dem dampfer
valdivia
1898 - 1899 , 18 ( 1 ) : 1 - 401 .
david , p . m . 1965 . the surface fauna of the ocean . endeavour ( oxf . ) 24 : 95 - 100 ) .
delle chiaje , s . 1825 . memorie sulla storia e notomia degli animali . senza verlebre del regno di napoli . i .
kramp , p . l . 1956 . pelagic fauna . p . 65 - 86 . in : ( a . bruun , sv . greve , h . mielche and r . spärck , eds . ) the galathea deep sea expedition 1950 - 1952 .
naef , a . 1921 / 23 . cephalopoda . fauna und flora des golfes von neapel . monograph , no . 35 .
nesis , k . n . 1982 / 7 . abridged key to the cephalopod mollusks of the world ' s ocean . 385 , ii pp . light and food industry publishing house , moscow . ( in russian . ) . translated into english by b . s . levitov , ed . by l . a . burgess ( 1987 ) , cephalopods of the world . t . f . h . publications , neptune city , nj , 351pp .
young , r . e . , m . vecchione and d . donovan . 1998 the evolution of coleoid cephalopods and their present biodiversity and ecology . south african jour . mar . sci . . , 20 : 393 - 420 .
page copyright © 2016 katharina m . mangold ( 1922 - 2003 ) , , and
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mangold ( 1922 - 2003 ) , katharina m . , michael vecchione , and richard e . young . 2016 . argonautidae
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linnaeus , c . ( 1758 ) . systema naturae per regna tria naturae , secundum classes , ordines , genera , species , cum characteribus , differentiis , synonymis , locis . editio decima , reformata . laurentius salvius : holmiae . ii , 824 pp . , available online at urltoken page ( s ) : 708 [ details ]
description mantle globular , as wide as long ; surface of mantle , head , arms , and web covered with conspicuous , closely - set , large , . . .
description mantle globular , as wide as long ; surface of mantle , head , arms , and web covered with conspicuous , closely - set , large , stellate tubercles ; a narrow , tuberculate , fold of skin encircles the lateral surface of the mantle ; funnel organ , 4 separate longitudinal pads . [ details ]
( of ocythoe antiquorum leach , 1817 ) leach w . e . ( 1817 ) . synopsis of the orders , families and genera of the class cephalopoda . the zoological miscellany ; being descriptions of new or interesting animals . 3 ( 30 ) : 137 - 141 . , available online at urltoken page ( s ) : 139 [ details ]
finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
finn j . k . ( 2014 ) . family argonautidae . pp . 228 - 237 , in p . jereb , c . f . e . roper , m . d . norman & j . k . finn eds . cephalopods of the world . an annotated and illustrated catalogue of cephalopod species known to date . volume 3 . octopods and vampire squids . fao species catalogue for fishery purposes [ rome , fao ] . 4 ( 3 ) : 353 pp . 11 pls . page ( s ) : 230 [ details ]
roper , c . f . e . , m . j . sweeney & c . e . nauen ( 1984 ) . fao species catalogue . vol 3 . cephalopods of the world . an annotated and illustrated catalogue of species of interest to fisheries . fao fish . synop . ( 125 ) , vol 3 : 277 p . [ details ]
branch , g . m . et al . ( 2002 ) . two oceans . 5th impression . david philip , cate town & johannesburg . , available online at urltoken [ details ]
gofas , s . ; afonso , j . p . ; brandào , m . ( ed . ) . ( s . a . ) . conchas e moluscos de angola = coquillages et mollusques d ' angola . [ shells and molluscs of angola ] . universidade agostinho / elf aquitaine angola : angola . 140 pp . ( look up in imis ) [ details ]
spencer , h . g . , marshall , b . a . & willan , r . c . ( 2009 ) . checklist of new zealand living mollusca . pp 196 - 219 . in : gordon , d . p . ( ed . ) new zealand inventory of biodiversity . volume one . kingdom animalia : radiata , lophotrochozoa , deuterostomia . canterbury university press , christchurch . [ details ]
judkins , h . l . , m . vecchione , and c . f . e . roper . 2009 . cephalopoda ( mollusca ) of the gulf of mexico , pp . 701–709 in felder , d . l . and d . k . camp ( eds . ) , gulf of mexico–origins , waters , and biota . biodiversity . texas a & m ; press , college station , texas . [ details ]
rosenberg , g . 1992 . encyclopedia of seashells . dorset : new york . 224 pp . page ( s ) : 178 [ details ]
liu j . y . [ ruiyu ] ( ed . ) . ( 2008 ) . checklist of marine biota of china seas . china science press . 1267 pp . ( look up in imis ) [ details ] available for editors [ request ]
lu , c . c . & chung , w . s . ( 2017 ) . guide to the cephalopods of taiwan . national museum of natural science , taichung , taiwan , 560 pp . isbn 978 - 986 - 05 - 2569 - 4 . page ( s ) : 516 [ details ]
( of ocythoe argonautae cuvier , 1829 ) check list of european marine mollusca ( clemam ) . , available online at urltoken [ details ]
( of ocythoe antiquorum leach , 1817 ) finn j . k . ( 2013 ) taxonomy and biology of the argonauts ( cephalopoda : argonautidae ) with particular reference to australian material . molluscan research 33 ( 3 ) : 143 - 222 . [ details ]
gleadall , i . g . ( 1997 ) . hong kong cephalopada : a brief review of current knowledge and identification of specimens collected in 1995 . in : morton b , editor . proceedings of the eighth international marine biological workshop : the marine flora and fauna of hong kong and southern china . the marine flora and fauna of hong kong and southern china iv . hong kong university press , hong kong . 503 - 513 . [ details ]
to museum of new ze . . . [ hosted externally ; from synonym ]
likes to be near the surface of the water . it is an epipelagic oceanic species .
the maximum length of shell is 30 cm in females , but only 1 . 5 - 2 cm in males . the shell is coiled and laterally compressed with a narrow keel and numerous sharp nodules . nodules toward the center of the coil are brown , but most of the shell is white .
the male uses a specialized arm called a ' hectocotylus ' to fertilize the eggs . the hectocotylus is inserted into the females pouch and breaks off during mating . the female forms a
nacelle ,
a thin calcareous shell , with two of her legs ( the others are used for swimming ) . this structure holds the eggs throughout development .
the female is up to twenty times larger than the male . normally these animals are solitary .
can be found in fish markets in india and japan . the shell is praised by collectors because of its beauty , coloration , sculpture , and fragility .
this animal is very common but is rarely spotted by humans . every once and a while many of them may be washed up by a change in currents or chased into shallow waters by predators , allowing people to observe and catch them .
the body of water between africa , europe , the southern ocean ( above 60 degrees south latitude ) , and the western hemisphere . it is the second largest ocean in the world after the pacific ocean .
body of water between the southern ocean ( above 60 degrees south latitude ) , australia , asia , and the western hemisphere . this is the world ' s largest ocean , covering about 28 % of the world ' s surface .
having body symmetry such that the animal can be divided in one plane into two mirror - image halves . animals with bilateral symmetry have dorsal and ventral sides , as well as anterior and posterior ends . synapomorphy of the bilateria .
the area in which the animal is naturally found , the region in which it is endemic .
structure produced by the calcium carbonate skeletons of coral polyps ( class anthozoa ) . coral reefs are found in warm , shallow oceans with low nutrient availability . they form the basis for rich communities of other invertebrates , plants , fish , and protists . the polyps live only on the reef surface . because they depend on symbiotic photosynthetic algae , zooxanthellae , they cannot live where light does not penetrate .
lane , frank . 1960 . kingdom of the octopus . sheridan house , new york .
roper , c . 1984 . cephalopods of the world . national museum , washington .
abbot , r . t . 1954 . american seashells . d . van nostrand co . , inc .
cousteau , jacques . 1973 . octopus and squid . doubleday and co . , new york .
disclaimer : the animal diversity web is an educational resource written largely by and for college students . adw doesn ' t cover all species in the world , nor does it include all the latest scientific information about organisms we describe . though we edit our accounts for accuracy , we cannot guarantee all information in those accounts . while adw staff and contributors provide references to books and websites that we believe are reputable , we cannot necessarily endorse the contents of references beyond our control .
this material is based upon work supported by the national science foundation grants drl 0089283 , drl 0628151 , due 0633095 , drl 0918590 , and due 1122742 . additional support has come from the marisla foundation , um college of literature , science , and the arts , museum of zoology , and information and technology services .
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argonauts occur in all tropical and temperate waters of the world . the exact number of species is not known . four species are currently recognised . the species are mainly distinguished by shell shape .
by well - developed connective apparatus conspicuous even in larvae . body firm , muscular ,
long , 1st much longer than others , 4th and 2nd shorter , 3rd are the shortest . fourth
10 - 20 % longer than 2nd , 1 . 5 - 2 times the length of 3rd . in maturing and mature females
present , photophores absent . twenty eight lamellae per demibranch in females . female builds characteristic thin , fragile calcareous
approx . 5 - 7 mm ; during subsequent life , beginning from approx . 8 mm ,
length . eggs very small ( 0 . 6 - 0 . 8 mm ) , laid and incubated in rear part of
wall . newborn larvae liberated by female probably every night . female begins to reproduce shortly after building
and continues to spawn eggs during entire life . males dwarfed , their 3rd left
everts and becomes much longer than male itself , detaches during mating . part of the
and remains there ; male dies after mating and is probably devoured by female . up to 3 hectocotyli may be found in one female . color of females purple - blue to wine - red from above , light from below ; extended 1st
not numerous ( < 35 ) , set far apart , nodules brown . fourth
much shorter than 2nd - 3rd , length in large females approx . 60 % of 2nd . egg size 0 . 7 - 0 . 8 mm . 20 lamellae per demibranch . a third
systema naturae per regna tria naturae , secundum classes , ordines , genera , species cum characteribus , differentiis , synonymis , locis .
sweeney , m . j . and c . f . e . roper / n . a . voss , m . vecchione , r . b . toll and m . j . sweeney , eds .
systematics and biogeography of cephalopods . smithsonian contributions to zoology , 586 ( i - ii )
turgeon , d . d . , a . e . bogan , e . v . coan , w . k . emerson , w . g . lyons , w . pratt , et al .
turgeon , d . d . , j . f . quinn , jr . , a . e . bogan , e . v . coan , f . g . hochberg , w . g . lyons , et al .
common and scientific names of aquatic invertebrates from the united states and canada : mollusks , 2nd ed .
taxon validity : [ fide robson ( 1932 : 181 ) ] . repository : ls syntypes . type locality :
pelago , m . indico , mediterrane
disclaimer : itis taxonomy is based on the latest scientific consensus available , and is provided as a general reference source for interested parties . however , it is not a legal authority for statutory or regulatory purposes . while every effort has been made to provide the most reliable and up - to - date information available , ultimate legal requirements with respect to species are contained in provisions of treaties to which the united states is a party , wildlife statutes , regulations , and any applicable notices that have been published in the federal register . for further information on u . s . legal requirements with respect to protected taxa , please contact the u . s . fish and wildlife service .
this page was last edited on 16 may 2017 , at 00 : 41 .
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ditropis is a genus of land snails with opercula , terrestrial gastropods in the family cyclophoridae .

there is also a hemipteran genus ditropis , homonym of stiroma fieber 1866 , belonging to the family delphacidae .

ditropis

ilia gjonov marked
ditropis pteridis
as trusted on the
ditropis pteridis
page .
no one has contributed data records for ditropis yet . learn how to contribute .
worms - world register of marine species - ditropis w . t . blanford , 1869
yan wong changed the thumbnail image of
file : lamna ditropis . jpg
.
kento furui added the japanese common name
ネズミザメ
to
lamna ditropis hubbs and follett , 1947
.
species ditropis ingenua o . boettger , 1891 accepted as ditropopsis ingenua ( o . boettger , 1891 ) ( original combination )
species ditropis moellendorffi o . boettger , 1891 accepted as ditropopsis moellendorffi ( o . boettger , 1891 ) ( original combination )
species ditropis spiralis o . boettger , 1891 accepted as ditropopsis spiralis ( o . boettger , 1891 ) ( original combination )
dana campbell set
file : salmon shark afsc . jpg
as an exemplar on
lamna ditropis hubbs and follett , 1947
.
dana campbell marked
file : salmon shark afsc . jpg
as trusted on the
lamna ditropis hubbs and follett , 1947
page .
dana campbell marked
file : salmon shark fetus . jpg
as trusted on the
lamna ditropis hubbs and follett , 1947
page .
anderson , scot d . , and kenneth j . goldman . 2001 . temperature measurements from salmon sharks , lamna ditropis , in alskan waters . copeia , 2001 ( 3 ) : 794 - 796 .
goldman , k . , j . musick . 2008 . the biology and ecology of the salmon shark , lamna ditropis . pp . 95 - 104 in m camhi , e pikitch , e babcock , eds .
to cite this page : lupton , e . ; a . mendoza and b . razavinematollahi 2012 .
lamna ditropis
( on - line ) , animal diversity web . accessed july 09 , 2018 at urltoken
blagoderov , a . i . 1994 . seasonal distribution and some notes on the biology of salmon shark ( lamna ditropis ) in the northwestern pacific ocean . j . ichthyol . , 34 ( 2 ) : 115 - 121 .
smith , r . l . , and d . rhodes . 1983 . body temperature of the salmon shark , lamna ditropis . j . mar . biol . assn . u . k . , 63 : 243 - 244 .
nakaya , kazuhiro . 1971 . descriptive notes on a porbeagle , lamna nasus , from argentine waters , compared with the north pacific salmon shark , lamna ditropis . bull . fac . fish . hokkaido univ , 21 : 269 - 279 .
nagasawa , kazuya . 1998 . predation by salmon sharks ( lamna ditropis ) on pacific salmon ( oncorhynchus spp . ) in the north pacific ocean . n . pac . anadr . fish comm . bull . , 1 : 419 - 433 .
paust , brian , and ronald smith . 1986 . salmon shark manual : the development of a commercial salmon shark , lamna ditropis , fishery in the north pacific . alaska sea grant report 86 - 01 . university of alaska , fairbanks . 430 pp .
nakaya , k . , 1971 . descriptive notes on a porbeable , lamna nasus , from argentine waters , compared with the north pacific salmon shark , lamna ditropis . bull . fac . fish . hokkaido univ . , 21 ( 4 ) : 269 - 79
the salmon shark , lamna ditropis , was first described by hubbs and follett in 1947 . the genus name lamna is translated from greek
lamna , - es
as a voracious fish . the species name ditropis is from the greek
di
meaning two , and
tropis
meaning keel . prior to 1947 , salmon sharks were thought to be porbeagle sharks , lamna nasus ( then lamna cornubica ) . although these species are closely related , their ranges do not overlap . salmon sharks are a pacific species , and porbeagles are an atlantic species .
tribuzio , c . 2004 .
an investigation of the reproductive physiology of two north pacific shark species : spiny dogfish ( squalus acanthias ) and salmon shark ( lamna ditropis )
( on - line pdf ) . school of aquatic and fishery sciences . accessed november 09 , 2011 at urltoken .
lamna ditropis hubbs and follett , 1947 . holotype , museum of comparative zoology , harvard university , mcz - 36471 , adult male ( partial specimen , size uncertain ) ; type locality , la jolla , california , 92 to 107m off the la jolla beach club in shallow water . copeia 1947 ( 3 ) : 194 .
these sharks are often mistake for white sharks because they look very similar , but the salmon shark is dark blue - gray to black over most of its body , except for its pale underside which often has dark blotches on it that the white sharks do not . they can get to 10 feet long ( almost 1 , 000 pounds ) from their short , conical snouts to their crescent caudal ( tail ) fins . unlike most others , this shark is endothermic , meaning it is able to maintain a body temperature above the temperature of the surrounding water .
the salmon shark gets its name from one of its prey items , the pacific salmon ( oncorhyncus spp . ) . although it is considered to be one of the main predators of pacific salmon , the salmon shark is actually an opportunistic feeder with a wide - ranging diet .
the salmon shark was called the porbeagle before it was recognized as a separate species . it belongs to the family lamnidae , the mackerel sharks . in french , the salmon shark is known as requin - taupe saumon , in spanish , marrajo salmón , and in german , pazifischer heringshai . the salmon shark is abundant in japanese waters , and it has several local names in japan , including the japanese mackerel shark , nezumizame , mokazame , radukazame , and sakezame .
the salmon shark is not specifically targeted by commercial fisheries , but is often caught as by - catch in japanese , united states , and canadian offshore gill - netting , seining , and trolling for salmon , swordfish , and thresher sharks . it is also sometimes caught by trammel - netting halibut fishers off california . salmon sharks are commonly viewed by fishermen as pests because of the heavy damage they do to fishing gear .
when salmon sharks are caught , the fins of the salmon shark may be harvested , but the carcass is generally discarded . however , if harvested , the flesh is sold for consumption in japan , and to a lesser extent in the u . s . the oil , skin ( leather ) , and fins ( soup ) may also be used . the people of the northern japanese fishing port of kesennuma , where most salmon shark landings in japan occur , also use the heart in a popular local sashimi dish .
the salmon shark is generally viewed as potentially dangerous to man . however , even though it is a relatively large shark and is related to infamously dangerous species like the white shark ( carcharodon carcharias ) and the shortfin mako ( isurus oxyrinchus ) , it has never been positively identified in any shark attack . the unsubstantiated reports of this species are probably due to confusion with the white shark . divers have viewed groups of salmon sharks underwater with no reports of agonistic behavior by the sharks .
the iucn is a global union of states , governmental agencies , and non - governmental organizations in a partnership that assesses the conservation status of species .
fishery statistics for this species are very limited , but as recent studies indicate low fecundity and slow maturity , it may be quite vulnerable . unfortunately , there is no regulation on the pelagic fishery in international waters , and the salmon shark is actually very heavily fished as bycatch , although often discarded . in general , fishermen view the salmon shark as a pest because of its frequent damage to fishing gear , particularly in salmon fisheries , and this means the shark is all the more likely to be killed or traumatized .
the recent frequent strandings of juvenile sharks along the pacific coast of the u . s . , which were rare in the 1970s and 1980s , indicate a possible adverse reaction to human development impacts along the coastal waters that are a nursery for this species .
due to the lack of biological knowledge of the salmon shark and increased sports fishing for it , the alaska board of fisheries closed all commercial shark fishing in alaska state waters and imposed heavy regulations on the state sports fishery for salmon sharks in 1997 .
the salmon shark occurs only in the coastal and oceanic waters of the north pacific . they can be found in the waters off japan ( including the sea of japan ) , off the western pacific coasts of north korea , south korea , russia ( including the sea of okhotsk ) , and in the bering sea . the eastern portion of their range is bounded by the eastern pacific coast of the canada , the u . s . , and possibly northern mexico . because the salmon shark only occurs in the pacific , it can be easily distinguished from its relative the porbeagle , in the northern hemisphere , which only occurs in the atlantic .
the salmon shark is a primarily pelagic species , but can be found in epipelagic , offshore , and coastal areas . it appears to prefer cold boreal to cool temperate waters , but has been caught in water temperatures from 36 . 5° to 75°f ( 2 . 5° to 24°c ) . the species can be found at the surface to depths below 500 ft ( 152 m ) , and has been photographed at 837 ft ( 255 m ) .
transmitter on the dorsal fin of a salmon shark , used to track vertical and horizontal migration . image courtesy national marine fisheries service
as is common among pelagic elasmobranch species , the salmon shark makes long oceanic migrations over the course of the year . in this species , these migrations appear to be highly correlated with
those of the pelagic fish that it principally preys on , as well as with reproductive seasons . the salmon shark gives birth in the spring and probably mates in the summer or autumn . populations in the northwest pacific breed in japanese waters or in waters off the coast of kamchatka and sakhalin . in winter , when the water warms , they migrate north to more distant feeding grounds in the sea of okhotsk , the bering sea , and the sea of japan . in the spring , they return south to japanese waters , areas of the open ocean , and the southern kuril region , where the females give birth .
populations of the northeast pacific perform a similar north - south migration in the waters off california , oregon , washington , alaska , and canada . the females migrate south in the spring to give birth off oregon and california , where a significant number of neonates and young juveniles are found beached at that time every year .
there appears to be a strong sexual segregation in this species with males dominating the western north pacific and females dominating the eastern north pacific . in fact , males and females probably do not form mixed groups , as catches of salmon sharks are almost always dominated by one sex or the other . although trans - pacific movements have not been documented , they are suspected to occur , particularly during the mating period , which is probably in summer or autumn .
salmon shark populations also appear to be segregated by size , with large sharks generally inhabiting the more northern reaches of the species ' range , and smaller sharks staying in the southern parts . the larger , more mature sharks are more active in migrations , like the ones described above , while juveniles tend to remain in nursery areas until they reach about 3 . 6 to 3 . 9 ft ( 110 to 120 cm ) in length . the waters off the coast of california appear to be a major nursery ground for the northeast populations , with juveniles remaining there for one to two years after birth . the northwest salmon shark populations have nursery grounds in the open - water pacific , japanese waters , and the southern kuril region .
the salmon shark has a heavy spindle - shaped body with a short blunt conical snout . the gill slits are large . the caudal peduncle is strongly keeled , with short secondary keels on the caudal base . the caudal fin is crescent - shaped . the large first dorsal fin has a free rear tip . the small second dorsal and anal fins can pivot .
the salmon shark is sometimes mistaken for the white shark ( carcharodon carcharias ) , but it can be distinguished by its shorter snout and the presence of secondary keels on the caudal base ( the white shark has none ) .
coloration the dorsal and lateral surfaces of the salmon shark are dark blue gray to black in color . its dorsal fin is all dark , including the rear tip . the ventral surface of the snout anterior to the mouth is also dark , but the rest of the ventral surface of the body is white , often with dusky blotches ( in adults only ) and white patches over the pectoral bases . the dark blotches can also be used to distinguish the salmon shark from the white shark .
close - up of the jaw of a salmon shark . photo courtesy national marine fisheries service
the salmon shark has moderately large blade - like teeth with lateral cusplets , small bumps or
mini - teeth
on either side of each tooth . the first upper lateral teeth have oblique ( diagonally - oriented ) cusps .
size , age , and growth the salmon shark has a maximum total length of about 10 ft ( 305 cm ) and maximum weight of over 992 lbs ( 450 kg ) . there are unconfirmed accounts of salmon sharks 12 . 1 to 14 . 1 ft ( 370 to 430 cm ) , but these may have resulted from confusion with the larger white shark . in the eastern north pacific , female salmon sharks can live to at least 20 years , males to at least 27 years .
in the western north pacific , males mature at about 5 . 8 to 6 . 1 ft ( 177 - 186 cm ) in total length and 5 years , and females mature at about 6 . 6 to 7 . 3 ft ( 200 - 223 cm ) and 8 - 10 years . salmon sharks in the eastern north pacific appear to have a faster growth rate than those in the western north pacific and mature at an earlier age . in the eastern north pacific , males mature at about 5 . 2 ft ( 158 cm ) and 3 - 5 years , and females at 6 . 7 ft ( 205 cm ) and 6 - 9 years . also , females in the eastern north pacific are in general larger and heavier bodied than those in the western north pacific .
as with all other members of the family lamnidae ( the mackerel sharks ) , the salmon shark is endothermic , meaning it is able to maintain a body temperature above the temperature of the surrounding water . this is unusual because most fish are ectotherms , having internal temperature that is nearly identical to the ambient water temperature .
all lamnids have vascular counter - current heat exchangers ( retia mirabilia ) that allow them to retain the heat produced by the metabolism of these fast - swimming sharks . salmon sharks have retes in the cranium near the eyes , in the locomotor muscles , and in the viscera . they also have vascular shunts that allow them to alter the route of blood flow , further regulating rates of heat gain and heat loss . a few other fast - swimming fish , like tunas , also have this homeothermic ability , so this is an instance of convergent evolution between lamnid sharks and tunas .
recent studies have shown that the salmon shark does indeed maintain an internal temperature well above ambient water temperature . in fact , the salmon shark probably has the greatest thermoregulatory ability of any shark , and internal body temperatures up to 60 . 1°f ( 15 . 6°c ) greater than sea surface temperature have been recorded .
this thermoregulatory ability allows salmon sharks to range vertically through the water column in search of prey and to extend their niche to boreal waters .
food habits salmon sharks are opportunistic feeders . their diet consists mainly of pelagic and demersal bony fishes , such as pacific salmon , steelhead trout , herring , sardines , pollock , alaska cod , tomcod , lancetfishes , daggerteeth , sauries , lanternfishes , pomfrets , mackerel , lumpfishes , sculpins , etc . non - bony fish prey include the spiny dogfish and pelagic squid . salmon sharks may feed singly or in feeding aggregations of several sharks .
salmon sharks are generally believed to be one of the principal predators of pacific salmon ( oncorhyncus spp . ) , but some studies suggest this may only be true for certain populations in certain areas of the salmon shark ' s range . in the aleutian islands and the gulf of alaska , for example , salmon shark abundance corresponds to catch rates of salmon , and the migration patterns of predator and prey appear to be linked . however , in the western north pacific , most salmon sharks appear to be concentrated south of the salmon ' s migration path . the migration patterns of these western north pacific populations appear to be linked instead with those of herring and sardines .
reproduction salmon sharks mate summer - autumn and give birth in the spring . during mating , the male shark bites the female to hold onto her while they copulate . accordingly , biologists can tell if a female has recently mated by looking for fresh bite marks .
this shark ' s gestation period is probably about nine months , with litters containing 2 - 5 embryos . it is ovoviviparous , meaning that it gives birth to live young , but in the uterus ( womb ) , embryos have no placental or other direct connection to the mother . oophagy , or consumption of unfertilized eggs by embryos , has been documented in this species . during gestation , the mother continues to ovulate unfertilized eggs ( ova ) , which proceed from the ovary to the nidamental gland , where they are filled with yolk . these nutritive ova then pass to the uterus , where they are consumed by the growing embryos . this is how embryos are nourished during most of gestation . embryos are born at about 2 . 8 to 3 . 1 ft ( 84 - 96 cm ) in length .
the white shark may prey on juvenile salmon sharks where their ranges overlap . photo © klaus jost
it is unlikely that any creature would prey on adult salmon sharks because of their size . however , juvenile salmon sharks probably do face predators among the larger fish , including other sharks , that inhabit their range .
parasites because this species is so little studied , reports of parasites found in it are few . there is a record of the cestode ( tapeworm ) nybelinia surmenicola found on a salmon shark in alaskan waters .
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thank you for taking the time to provide feedback on the iucn red list of threatened species website , we are grateful for your input .
no detailed information exists on salmon shark abundance , and nothing is known about stock structure . no abundance estimates are available for salmon sharks in the northeast pacific . minimum stock size for the northwest and western central pacific has been estimated via catch data from several japanese drift / gillnet fisheries to range from 1 . 66 x 106 to 2 . 19 x 106 ( shimida and nakano unpublished data , cited in nagasawa 1998 ) , however no detailed information was given as to how these estimates were obtained . while sexual segregation is relatively common in sharks , a remarkable sex ratio difference occurs in salmon sharks across the north pacific basin . the western side is male dominated and the eastern side is female dominated , with dominance increasing with latitude ( sano 1962 , nagasawa 1998 , goldman 2002 , goldman and musick in press ) . larger sharks range farther north than smaller individuals , and southern catches generally occur in deeper waters ( nagasawa 1998 , goldman and musick unpublished data ) .
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the webpage text is licensed under a creative commons attribution - noncommercial 4 . 0 license
froese , r . & d . pauly ( editors ) . ( 2018 ) . fishbase . world wide web electronic publication . , available online at urltoken [ details ]
compagno , l . j . v . ( 2001 ) . sharks of the world . an annotated and illustrated catalogue of shark species known to date . volume 2 . bullhead , mackerel and carpet sharks ( heterodontiformes , lamniformes and orectolobiformes ) . fao species catalogue for fishery purposes . no . 1 , vol . 2 . rome , fao . 269p . [ details ]
ditropopsis ( ditropiphorus ) fukuda , 2000 represented as ditropopsis e . a . smith , 1897
bank , r . ( 2017 ) . classification of the recent terrestrial gastropoda of the world . last update : july 16th , 2017 . [ details ]
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one of a large number of brachypterous ( short - winged ) delphacids , although the only one to specialise on bracken . the vertex and face are uniformly yellow and the wings dark with smooth and inconspicuous veins . the wings are approximately half the length of the abdomen in males and a quarter the length in females . macropters are rare . common and widespread in britain , often on bracken in woods .
salmon sharks are widely distributed throughout coastal and pelagic environments within the subarctic and temperate north pacific ocean , between 10°n and 70°n latitude . their range includes the bering sea , the sea of okhotsk , and the sea of japan , and also extends from the gulf of alaska to southern baja california . salmon sharks generally range from 35°n to 65°n latitude in the western pacific ocean and from 30°n to 65°n in the eastern pacific , with highest densities found between 50°n and 60°n .
salmon sharks are primarily pelagic , but are also found in coastal waters of the north pacific . they generally swim in the surface layer of subarctic water , but also occur in deeper waters of warmer southern regions to at least 150m . this species appears to prefer water temperatures from 2°c to 24°c .
populations of salmon sharks show seasonal density fluctuations in the coastal alaska downwelling region , which is characterized by turbulent mixing and strong seasonality of light and temperature . the summer - autumn usage of this ecoregion by salmon sharks coincides with the return of
adult salmon sharks can weigh at least 220 kg ( 485 lbs ) . there are unofficial reports of salmon sharks weighing 450 kg ( 992 lbs ) , but it is likely that this specimen was a misidentified white shark (
) . sharks in the eastern north pacific have a greater weight to length ratio than their counterparts in the western north pacific .
when reporting shark lengths , precaudal length ( pcl ) is often used , even though it excludes the tail fin . this allows discussion of a standardized length measure , as different possible orientations of the tail can give different measurements of total length . the pcl is determined by calculating the straight - line - distance between two vertical lines , one projected from the tip of the snout , and the other from the precaudal point . adult salmon sharks typically range in size from 180 to 210 cm pcl .
most fishes are ectotherms , meaning their body temperature remains identical to the surrounding water . salmon sharks , however , are endothermic , meaning they maintain a core body temperature higher than the surrounding water ( up to 16°c ) . this is accomplished through retention of heat produced by cell metabolism . however , no information on the basal metabolic rate of
salmon sharks have a heavy , spindle - shaped body with a short , conical snout . these sharks have relatively long gill slits . the mouth is broadly rounded , with the upper jaw containing 28 to 30 teeth and the lower jaw containing 26 to 27 moderately large , blade - like teeth with cusplets ( small bumps or “mini - teeth” ) on either side of each tooth . unpaired fins consist of a large first and much smaller second dorsal fin , a small anal fins and a crescent - shaped caudal fin . the caudal fin is homocercal , meaning the dorsal and ventral lobes are nearly equal in size . paired fins include large pectoral fins and much smaller pelvic fins , which are modified to form reproductive structures in males . a distinctive keel is present on the caudal peduncle and a short secondary keel is present on the caudal base . dorsal and lateral areas are dark bluish - gray to black . the belly is white , and often includes various dark paatches in adults . the ventral surface of the snout is also dark - colored .
) by the presence of a secondary keel on the caudal base , dark coloration on the ventral surface of the snout , and dusky patches on the belly , all of which are lacking in great whites . salmon sharks are also similar in appearance to porbeagle sharks (
) , but can easily be distinguished by their distributions ( porbeagles are absent from the north pacific range of salmon sharks ) .
, only the right ovary of salmon sharks is functional . fertilization is internal , and development proceeds within the uterus . salmon sharks are ovoviviparous , but developing embryos maintain no direct connection to the mother to obtain nutrition . oophagy has been observed in this species , and likely represents the primary source of nutrition for developing embryos . the pregnant female ovulates and the unfertilized eggs are sent to the nidamental gland , where they are filled with yolk . the eggs are then moved to the uterus , where the embryos can feed on them . litters tend to contain 4 to 5 young , which are approximately 60 to 65 cm pcl at birth .
little is known about how salmon sharks find and select mates , although seasonal migrations and aggregations of individuals likely facilitates this process . males hold on to females by biting their pectoral fin during copulation , which consists of the insertion of one of the male ' s claspers ( modified pelvic fins ) into the female ' s cloaca . couples have no further contact following copulation .
salmon sharks mate in northern waters during autumn and give birth after a 9 month gestation period , during their southern migration in late spring through early summer . individuals that populate the central and western north pacific are thought to breed off the coast of honshu , japan . those that populate the eastern north pacific breed off the coasts of oregon and california . pups are born in nursery grounds in the central north pacific transition zone or along the coast of united states and canada . female salmon sharks in the western north pacific reproduce annually , and are estimated to bear 70 offspring in their lifetime , while evidence suggests that females in the eastern north pacific reproduce every two years .
sexual maturity of males in the western north pacific is estimated to occur at approximately 140 cm pcl ( corresponding to an age of 5 years ) , and between 170 and 180 cm ( ages 8 to 10 years ) for females . for salmon sharks in the eastern north pacific , sexual maturity is reached between 125 and 145 cm pcl ( ages 3 to 5 years ) for males and 160 to 180 cm ( ages 6 to 9 ) for females . salmon sharks in both regions reach maximum lengths of approximately 215 cm pcl for females and about 190cm pcl for males .
breeding interval females in the eastern north pacific breed every two years , while those in the western north pacific breed annually .
females provide nutrition to their embryos through unfertilized eggs , which are consumed by the developing young . protection is provided to embryos through residence within the mother ' s uterus until they have fully developed and are able to fend for themselves .
the maximum age of salmon sharks has been estimated through vertebral analysis . in both western and eastern north pacific populations longevity estimates are similar , between 20 and 30 years . salmon sharks are not currently held in captivity in large oceanaria and there is no published information regarding their lifespan under captive conditions .
like many shark species , salmon sharks segregate by size and sex . in this species , an interesting sex ratio difference has been observed across the north pacific basin . the western population is dominated by males whereas the eastern population is dominated by females . a north / south segregation has also been noted , with larger sharks ranging farther north than smaller ones . salmon sharks are known to hunt both alone and in feeding aggregations of several individuals ( up to 30 to 40 sharks have been observed in these schools ) . they are seasonal migrants , and are strongly suspected to follow the movements of preferred prey items . in the case of eastern north pacific populations , the prey item followed appears to be
. the distributional and migratory patterns of both subpopulations also appears to be influenced by the sex , size , and age of individuals .
while information on intraspecific communication in salmon sharks is lacking , this species , like other cartilaginous fishes , perceives its environment using visual , olfactory , chemo - and electroreceptive , mechanical , and auditory sensory systems .
) , mackerel ( scombridae ) , lumpfishes ( cyclopteridae ) , sculpins ( cottidae ) , and other fish that they can capture .
( goldman and musick , 2008 ; nagasawa , 1998 ; roman , 2010 ;
tagging of pacific predators , salmon shark .
, 2010 )
) . once maturity is reached , salmon sharks occupy the highest trophic level in the food web of subarctic waters , alongside marine mammals and seabirds . the only known predators of mature salmon sharks are humans .
small salmon sharks are found in abundance in waters north of the subarctic boundary , which are thought to be their nursery ground . there they can avoid predation by larger sharks , which inhabit areas that are further north or south . juveniles also display obliterate countershading , and lack the dark blotches found on the ventral areas of adults .
salmon sharks are apex predators in subarctic waters , helping to regulate populations of their prey species within the ecosystem .
shark meat and shark fins have high economic value and salmon sharks are often caught by commercial fisheries , although this is often as bycatch in pursuit of other species . in japan , their hearts are used for sashimi . they are also caught by sports fishermen for recreation .
( roman , 2010 ;
tagging of pacific predators , salmon shark .
, 2010 )
salmon sharks , when caught unintentionally as bycatch , cause problems for commercial salmon fishermen . the sharks cause damage to seines and gillnets , loss of hooked or netted salmon , and damage to trolling gear .
salmon sharks are potentially dangerous to humans , although there are no positively documented attacks . unsubstantiated reports of attacks by this species are likely due to misidentification of more aggressive species , such as great whites .
salmon sharks are currently listed as
data deficient
by the iucn red list . its low number of young and slow maturity may make it vulnerable to overfishing , but few fishery statistics exist for the species , and its fishery is unregulated in international waters . however , due to this lack of knowledge and the potential impact of fishing on this species ' populations , heavy regulations were imposed on alaskan sport fishing for this species in 1997 .
emily lupton ( author ) , san diego mesa college , anthony mendoza ( author ) , san diego mesa college , brian razavinematollahi ( author ) , san diego mesa college , paul detwiler ( editor ) , san diego mesa college , jeremy wright ( editor ) , university of michigan - ann arbor .
living in the nearctic biogeographic province , the northern part of the new world . this includes greenland , the canadian arctic islands , and all of the north american as far south as the highlands of central mexico .
body of water between the southern ocean ( above 60 degrees south latitude ) , australia , asia , and the western hemisphere . this is the world ' s largest ocean , covering about 28 % of the world ' s surface .
living in the northern part of the old world . in otherwords , europe and asia and northern africa .
having body symmetry such that the animal can be divided in one plane into two mirror - image halves . animals with bilateral symmetry have dorsal and ventral sides , as well as anterior and posterior ends . synapomorphy of the bilateria .
having markings , coloration , shapes , or other features that cause an animal to be camouflaged in its natural environment ; being difficult to see or otherwise detect .
having a body temperature that fluctuates with that of the immediate environment ; having no mechanism or a poorly developed mechanism for regulating internal body temperature .
offspring are produced in more than one group ( litters , clutches , etc . ) and across multiple seasons ( or other periods hospitable to reproduction ) . iteroparous animals must , by definition , survive over multiple seasons ( or periodic condition changes ) .
the area in which the animal is naturally found , the region in which it is endemic .
reproduction in which eggs develop within the maternal body without additional nourishment from the parent and hatch within the parent or immediately after laying .
an aquatic biome consisting of the open ocean , far from land , does not include sea bottom ( benthic zone ) .
the regions of the earth that surround the north and south poles , from the north pole to 60 degrees north and from the south pole to 60 degrees south .
the kind of polygamy in which a female pairs with several males , each of which also pairs with several different females .
that region of the earth between 23 . 5 degrees north and 60 degrees north ( between the tropic of cancer and the arctic circle ) and between 23 . 5 degrees south and 60 degrees south ( between the tropic of capricorn and the antarctic circle ) .
tagging of pacific predators . 2010 .
tagging of pacific predators , salmon shark .
( on - line ) . tagging of pacific predators . accessed november 02 , 2011 at urltoken .
francis , m . , l . natanson , s . campana . 2008 . the biology and ecology of the porbeagle shark , lamna nasus . pp . 105 - 113 in m camhi , e pikitch , e babcock , eds .
roman , b . 2010 .
ichthyology at the florida museum of natural history / education biological profiles : salmon shark
( on - line ) . florida museum of natural history . accessed october 10 , 2011 at urltoken .
disclaimer : the animal diversity web is an educational resource written largely by and for college students . adw doesn ' t cover all species in the world , nor does it include all the latest scientific information about organisms we describe . though we edit our accounts for accuracy , we cannot guarantee all information in those accounts . while adw staff and contributors provide references to books and websites that we believe are reputable , we cannot necessarily endorse the contents of references beyond our control .
this material is based upon work supported by the national science foundation grants drl 0089283 , drl 0628151 , due 0633095 , drl 0918590 , and due 1122742 . additional support has come from the marisla foundation , um college of literature , science , and the arts , museum of zoology , and information and technology services .
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fao fisheries synopsis , no . 125 , vol . 4 , pt . 1
sharks of the world : an annotated and illustrated catalogue of shark species known to date , vol . 2 : bullhead , mackerel and carpet sharks ( heterodontiformes , lamniformes and orectolobiformes )
special publication of the center for biodiversity research and information , no . 1 , vol 1 - 3
nelson , joseph s . , edwin j . crossman , h . espinosa - pérez , l . t . findley , c . r . gilbert , et al . , eds .
full author list : nelson , joseph s . , edwin j . crossman , héctor espinosa - pérez , lloyd t . findley , carter r . gilbert , robert n . lea , and james d . williams
robins , richard c . , reeve m . bailey , carl e . bond , james r . brooker , ernest a . lachner , et al .
disclaimer : itis taxonomy is based on the latest scientific consensus available , and is provided as a general reference source for interested parties . however , it is not a legal authority for statutory or regulatory purposes . while every effort has been made to provide the most reliable and up - to - date information available , ultimate legal requirements with respect to species are contained in provisions of treaties to which the united states is a party , wildlife statutes , regulations , and any applicable notices that have been published in the federal register . for further information on u . s . legal requirements with respect to protected taxa , please contact the u . s . fish and wildlife service .
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en - salmon shark , fr - requin - taupe saumon , sp - marrajo salmón .
fieldmarks : heavy spindle - shaped body , short conical snout , moderately large blade - like teeth with lateral cusplets , long gill slits , large first dorsal fin with dark free rear tip , minute , pivoting second dorsal and anal fins , strong keels on caudal peduncle , short secondary keels on caudal base , crescentic caudal fin , underside of preoral snout dark , often dusky blotches on ventral surface of body and white patches over pectoral bases .
snout short and bluntly pointed , with preoral length 4 . 5 to 7 . 6 % of total length ( adults 4 . 5 to 5 . 0 % ) , space from eye to first gill slit 1 . 3 to 1 . 9 times preorbital length . first upper lateral teeth with oblique cusps .
total vertebral count 170 , precaudal vertebral count 103 . cranial rostrum expanded as a huge hypercalcified knob which engulfs most of the rostral cartilages except bases in adults .
colour : dark grey or blackish on dorsolateral surface of body , white below , with white abdominal colour extending anteriorly over pectoral bases as a broad wedge - shaped band ; first dorsal fin without a white free rear tip ; ventral surface of head dusky and abdomen with dusky blotches in adults but not in young .
coastal and oceanic . north pacific : japan ( including sea of japan ) , north korea , south korea , and the pacific coast of russia ( including sea of okhotsk ) to bering sea and the eastern pacific coast of the usaand canada ( alaska south to british columbia , washington , oregon , and southern california ) and probably mexico ( northern baja california ) .
maximum total length about 305 cm ; anecdotal accounts mention sizes of 3 . 7 to 4 . 3 m tl but cannot be confirmed , and confusion with the larger white shark is possible and has happened . size at birth between 40 and 50 cm and 85 cm tl , with the largest foetuses at least 70 cm long and the smallest free - ranging young between 40 and 50 cm . males maturing at about 182 cm tl ( 5 years ) and females at about 221 cm tl ( 8 to 10 years ) ; both sexes adult over about 210 to 220 cm tl .
sharks of the world an annotated and illustrated catalogue of shark species known to date . volume 2 bullhead , mackerel and carpet sharks ( heterodontiformes , lamniformes and orectolobiformes ) . leonard j . v . compagno 2001 . fao species catalogue for fishery purposes . no . 1 , vol . 2 . rome , fao . 2001 . p . 269 .
named comes from the greek ' di ' meaning two and ' tropis ' meaning keel ( ref . 6885 )
marine ; pelagic - oceanic ; oceanodromous ( ref . 51243 ) ; depth range 0 - 650 m ( ref . 50550 ) , usually 0 - 152 m ( ref . 55221 ) . temperate ; 66°n - 22°n , 120°e - 115°w
north pacific : japan , korea , and the sea of okhotsk to the bering sea and southward to southern california , usa ( ref . 247 ) and baja california , mexico ( ref . 9253 ) .
maturity : l m ? , range 180 - 240 cm max length : 305 cm tl male / unsexed ; ( ref . 247 ) ; common length : 180 cm tl male / unsexed ; ( ref . 9988 ) ; max . published weight : 175 . 0 kg ( ref . 9988 )
dorsal spines ( total ) : 0 ; dorsal soft rays ( total ) : 0 ; anal spines : 0 ; anal soft rays : 0 . first dorsal fin uniformly dark , no light rear tip ; ventral surface of body white with dusky blotches ( ref . 247 ) .
a coastal - littoral and epipelagic shark that prefers boreal to cool temperate waters , from the surface to at least 152 m ( ref . 247 ) . common in continental offshore waters but range inshore to just off beaches ( ref . 247 ) . occurs singly or in schools or feeding aggregations of several individuals ( ref . 247 ) . feeds on fishes ( ref . 247 ) . ovoviviparous , embryos feeding on yolk sac and other ova produced by the mother ( ref . 50449 ) . with up to 4 young in a litter ( ref . 247 ) . fast swimmer ( ref . 9988 ) . potentially dangerous but has never or seldom been implicated in human attacks ( ref . 247 ) . causes considerable damage to commercial catches and gear ( ref . 6885 ) . utilized fresh , dried or salted , and frozen ; fins , hides and livers are also used , with fins having particular value ; can be broiled and baked ( ref . 9988 ) .
exhibit ovoviparity ( aplacental viviparity ) , with embryos feeding on other ova produced by the mother ( oophagy ) after the yolk sac is absorbed ( ref . 50449 ) . litter size is up to 4 young ( ref . 247 ) . distinct pairing with embrace ( ref . 205 ) .
compagno , l . j . v . , 1984 . fao species catalogue . vol . 4 . sharks of the world . an annotated and illustrated catalogue of shark species known to date . part 1 - hexanchiformes to lamniformes . fao fish . synop . 125 ( 4 / 1 ) : 1 - 249 . rome , fao . ( ref . 247 )
) : 1 . 7 - 8 . 7 , mean 4 . 7 ( based on 832 cells ) .
phylogenetic diversity index ( ref . 82805 ) : pd 50 = 0 . 7813 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .
bayesian length - weight : a = 0 . 00933 ( 0 . 00405 - 0 . 02151 ) , b = 3 . 04 ( 2 . 84 - 3 . 24 ) , in cm total length , based on lwr estimates for this ( sub ) family - body shape ( ref . 93245 ) .
trophic level ( ref . 69278 ) : 4 . 5 ±0 . 80 se ; based on food items .
resilience ( ref . 69278 ) : very low , minimum population doubling time more than 14 years ( fec = 4 ) .
vulnerability ( ref . 59153 ) : high vulnerability ( 59 of 100 ) .
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reefquest centre for shark research text and illustrations © r . aidan martin copyright | privacy
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