sepiola atlantica , also known as the atlantic bobtail , is a species of bobtail squid native to the northeastern atlantic ocean ( 65ºn to 35ºn ) , from iceland , the faroe islands and western norway to the moroccan coast .

there is a single record of this species from the mediterranean sea .

both sexes of s. atlantica grow to around 21 mm ( 0.83 in ) in mantle length .

the type specimen was collected in the bay of biscay and is deposited at the muséum national d'histoire naturelle in paris .

sepiola atlantica

individual sepiola atlantica on gravel . image width ca xx cm . image : paul naylor
pair of little cuttlefish , sepiola atlantica , mating photographic print by brian j . skerry at urltoken
figure . distribution of sepiola atlantica . map from guerra ( 2012 , modified from jereb and roper ( 2005 ) .
s . atlantica sitting on the bottom in an alert posture . © m . e . garcí
yau , c . & boyle , p . r . , 1996 . ecology of sepiola atlantica ( mollusca : cephalopoda ) in the shallow sublittoral zone journal of the marine biological association of the united kingdom , 76 , 733 - 748 .
rodrigues , m , garci , m . e . , guerra a and troncoso , j . s . 2009 . mating behaviour of the atlantic bobtail squid sepiola atlantica ( cephalopoda : sepiolidae ) . vie et milieu , 59 : 1 - 5 .
rodrigues , m . , garcì , m . e . , troncoso , j . s . and guerra , a . 2011 . spawning strategy in atlantic bobtail squid sepiola atlantica ( cephalopoda : sepiolidae ) . helgoland marine research , 65 : 43 - 49 .
sur l ' accouplement de quelques cephalopodes sepiola rondeletii ( leach ) , rossia macrosoma ( d . ch . ) et octopus vulgaris ( lam . )
rodrigues , m , garcì , m . e . , troncoso , j . s . and guerra , a . 2011 . seasonal abundance of the atlantic bobtail squid sepiola atlantica in galician waters ( ne atlantic ) . marine biological reseach , 7 : 812 - 819 .
figure . eggs of s . atlantica deposited on the side of an aquarium . photographed by m . e . garcí .
rodrigues , m . , garcì , m . e . , troncoso , j . s . and guerra , a . 2010 . burying behaviour in the bobtail squid sepiola atlantica ( cephalopoda : sepiolidae ) , italian journal of zoology , 77 : 2 , 247 - 251 .
( of sepiola vulgaris gervais & van beneden , 1839 ) check list of european marine mollusca ( clemam ) . , available online at urltoken [ details ]
rodrigues , m . , guerra , a . , troncoso , j . s . 2010 . embryonic phase and hatchling size in atlantic bobtail squid sepiola atlantica ( cephalopoda : sepiolidae ) . 17th international congress of unitas malacologica . world congress of malacology 18 - 24 july 2010 , phuket , thailand .
figure . ventral view of s . atlantica with mantle cut to show photophore . arrow points to left reflector . photograph by a . guerra .
wilson , e . 2008 . sepiola atlantica little cuttlefish . in tyler - walters h . and hiscock k . ( eds ) marine life information network : biology and sensitivity key information reviews , [ on - line ] . plymouth : marine biological association of the united kingdom . [ cited 09 - 07 - 2018 ] . available from : urltoken
figure . dorsal views of young s . atlantica . left - newly hatched . photograph by m . e . garcí . right - juvenile . photograph by m . rodrigues .
figure . side view of the mating posture of s . atlantica . the male is to the left underneath the female on the right . photograph by m . e . garcí .
gabel - deickert a ( 1995 ) reproductive patterns in sepiola affinis and other sepiolidae ( mollusca : cephalopoda ) . in : boletzky sv ( ed ) mediterranean sepiolidae . bulletin de l’institut océonographique , monaco , nº special 16 , pp 73–83
sepiola atlantica is a neritic species found in the eastern north atlantic . it occurs in waters just below the intertidal zone to depths of 150 m but is most common below 50 m in scottish waters but between 6 and 50 m in galician waters of the rìas ( sheltered tectonic valleys of spain ) and prefers clean sandy bottoms ( guerra , 2012 ) . it is primarily benthic but leaves the bottom to forage for food . like most sepiolids , s . atlantica is a small species reaching a maximum of 25 mm ml in both sexes , although the average size of adults is 12 - 15 mm ml ( rodrigues et al , 2011 ) .
figure . anterior view of s . atlantica as it finishes burying itself in the sand . arms ii are brushing sand over the head to complete the cover . photograph from rodrigues et al . ( 2010 ) .
s . atlantica is found throughout much of the northeastern atlantic from iceland to morocco ( about 65°n - 35°n latitude ( rodrigues , et al . , 2011 ) but is rarely found in the mediterranean sea ( cephstock ref ) .
the aim of this work is therefore to add new information to the knowledge of the reproductive strategy of s . atlantica through direct observation of specimens in captivity , and to compare these patterns with those known of other members of the family sepiolidae .
this study aimed to determine the spawning strategy in the atlantic bobtail squid sepiola atlantica , in order to add new information to the knowledge of its reproductive strategy . a total of 12 females that spawned in aquaria were examined . characteristics of the reproductive traits and egg clutches were similar to those of other known sepiolidae . clutch size varied from 31 up to 115 eggs . females of this species had incorporated up to 1 . 58 times of their body weight into laid eggs . the size of laid eggs showed a positive correlation with maternal body size , supporting the idea that female size is a determinant of egg size . our data suggest that s . atlantica is an intermittent terminal spawner , and that its spawning strategy comprises group - synchronous ovary maturation , multiple egg laying , and deposition of egg clutches in different locations . the obtained data provide insights for future comparative studies on reproductive allocation .
the little cuttle or sepiola atlantica is one of the smallest cuttlefish in british waters . it is found all around our coasts and is about 5cms long . it is usually found half buried in sand but is very difficult to spot as it can rapidly adapt its colour to its surroundings . it is an active and efficient predator , feeding on small fish and crustaceans . it carefully and slowly stalks its prey which it catches with two long , retractile tentacles which it shoots forward when it is in range . the one in the illustration was disturbed by my camera and adopted its threat display mode and tried to make itself look bigger .
s . atlantica , like a number of other sepiolids , often buries itself in the sand during the daytime , with just the eyes slightly protruding or only the pupil of the eye exposed . the bobtail squid can bury itself in about 20 sec ( rodrigues , et al . , 2010 ) .
( of heterosepiola atlantica ( d ' orbigny [ in férussac & d ' orbigny ] , 1839–1842 ) ) perkins , e . j . 1971 . the marine fauna and flora of the solway firth area : part 3 . transactions of the dumfriesshire and galloway natural history and antiquarian society 48 : 12 - 68 . [ details ]
s . atlantica . egg capsules laid in an aquarium . a batch of eggs attached to an aquarium wall just below the water surface ; b egg capsules attached laterally to one another ; c egg capsules laid individually on the sand bottom , and covered with sand grains . scale bars : 7 mm ( a ) , 3 mm ( b , c )
like other sepiolidae such as s . atlantica ( rodrigues et al . , 2011 ) , e . tasmanica spawn more than once ( rocha et al . , 2001 ) and deposit eggs in discrete clutches at different times and locations . there is also substantial variation in the number of eggs per clutch and in the total number of eggs each female produces , perhaps representing the potential for plasticity in these traits .
sepiolid squid are small - bodied and benthic and are useful model organisms as they are more easily maintained in laboratory conditions than pelagic or larger - bodied cephalopods ( boletzky & boletzky , 1971 ) . copulation has been observed in numerous sepiolids : in euprymna ( singley , 1983 ; hanlon et al . , 1997 ; nabhitabhata et al . , 2005 ) , sepiola ( racovitza , 1894 ; boletzky , 1983 ; rodrigues , et al . , 2009 ) , sepietta ( bergstrom & summers , 1983 ) and rossia ( racovitza , 1894 ) , as summarized by rodrigues et al . ( 2009 ) . for most sepiolids , there is no courtship ( bergstrom & summers , 1983 ; singley , 1983 ; nabhitabhata et al . , 2005 ; rodrigues et al . , 2009 ) and mating occurs in a ‘male - to - female neck’ position ( boletzky , 1983 ; singley , 1983 ; hanlon et al . , 1997 ; nabhitabhata et al . , 2005 ; rodrigues et al . , 2009 ) . mating duration varies both within and between species , from 8 min recorded in sepiola rondeletii ( racovitza , 1894 ) to up to 80 min recorded in s . atlantica and euprymna scolopes ( singley , 1983 ; rodrigues et al . , 2009 ) . the reproductive period of most sepiolids is aseasonal ( jereb , mazzola & di stephano , 1997 ) and spawning patterns have been described for many species , summarized by rodrigues et al . ( 2011 ) . females generally produce numerous eggs in a series of clutches , producing in total between 50 and 200 eggs per female ( mangold , 1987 ) . however , potential fecundity ( which includes oocytes in the ovary and ripe eggs in oviduct ) of up to 931 eggs has been recorded in rossia macrosoma ( salman & onsoy , 2010 ) .
euprymna tasmanica females laid multiple egg clutches over a long period of time ; some females laid eggs over 4 months . the average lay span ( 46 . 61 ± 5 . 06 d ) , from their first clutch to their last clutch , is longer than previously recorded in other sepiolid squids under laboratory conditions ( 1–61 d recorded in sepiola affinis by gabel - deickert , 1995 ; 3–30 d in s . atlantica by rodrigues et al . , 2011 ) . this is perhaps because the average number of days between each clutch is also longer , at least compared with s . atlantica ( rodrigues et al . , 2011 ) . the number of clutches produced falls within the range previously reported in that species ( rodrigues et al . , 2011 ) . clutch size is comparable with those of other sepiolidae ( bello & deickert , 2003 ) , as are the total number of eggs produced , with a mean of 245 . 13 ± 23 . 98 in e . tasmanica and a range of 50–250 eggs recorded for e . scolopes ( hanlon et al . , 1997 ) , 108–464 eggs for e . hyllebergi ( nabhitabhata et al . , 2005 ) —although some e . tasmanica laid up to 646 eggs . when compared with potential fecundity ( oocytes in the ovary and ripe eggs in oviduct ) recorded in other sepiolidae , the maximum number of laid eggs reported here for e . tasmanica is within the range reported for r . macrosoma ( 382–837 oocytes ) , r . pacifica ( 300–1300 oocytes ) , neorossia caroli jeannea ( c . 200–800 oocytes ) ( laptikhovsky et al . , 2008 ) and r . macrosoma ( 126–931 oocytes ) ( salman & onsoy , 2010 ) .
steer et al . ( 2004 ) found no correlation between egg volume and hatchling mass , or egg volume and female mass , in a laboratory study on a tasmanian population of e . tasmanica . in contrast , we found a significant relationship between egg mass and hatchling mass ( although with a low r 2 value ) and a trend for a positive effect of female mass on egg mass . steer et al . ( 2004 ) measured egg volume rather than mass and this alternate method of quantifying egg size may explain the different results . however , rodrigues et al . ( 2011 ) found a significant correlation between egg volume and hatchling mantle length in s . atlantica . a significant positive correlation between female mass and individual egg mass has also been found in many sepiolid species including s . affinis , s . rondeletii , s . intermedia , sepietta obscura and sepietta oweniana ( gabel - deickert , 1995 ) . rodrigues , guerra & troncoso ( 2012 ) also found a positive correlation between female mantle length in s . atlantica and ripe oocyte mass . however , it may be that yolk concentration and composition of the egg are more important ( albeit more difficult to determine ) measures of egg quality than egg size ( steer et al . , 2004 ) .
s . atlantica is a intermittent terminal spawner ( ie , somatic growth growth of the female does not occur between spawning bouts ) although the females feed between spawning bouts . eggs are laid in batches of 31 - 115 . the female dies within a day of spawning the final batch . spawning period from first to last clutch spawned can be up to 20 days . spawning occurs at night but the duration of the nighttime spawning event is unknown . mature oocytes vary in size between about 2 . 7 and 3 . 8 mm roughly depending on the size of the female . potential fecundity can be up to 304 and actual fecundity can be up to 111 eggs spawned .
mating in e . tasmanica lasts substantially longer ( by up to 82 min ) than in the sepiolid squids sepiola rondeletii and rossia macrosoma ( racovitza , 1894 ) . there was also substantial variation in the duration of copulation among mating pairs ( range 45–184 min ) and this is comparable with ranges previously recorded for e . scolopes ( 45–80 min by singley , 1983 , and 30–50 min by hanlon et al . , 1997 ) . in mating pairs that were forcibly separated during mating ( z . e . squires , unpubl . ) , uneverted spermatophores were still attached to the hectocotylus , suggesting that the extended duration may relate to spermatophore eversion times and the complex process of evagination ( hoving et al . , 2009 ; marian , 2012a , b ) . mating duration was shorter at higher temperatures , which could hasten the eversion process .
additionally , temperature also affects egg size ( smaller eggs are produced at higher temperatures ) and the rate of egg laying ( eggs are laid faster at higher temperatures ) . this is probably due to the effects of temperature on metabolism in squid , such that females that grow faster at higher temperatures ( andre et al . , 2009 ) may have more available resources for producing eggs and can therefore produce eggs at a faster rate . the low hatching success recorded in this study was similar to that in another laboratory study of e . tasmanica ( sinn et al . , 2006 ) . other studies have recorded much higher hatching successes in other species , for example up to 98 . 5–100 % in s . atlantica ( rodrigues et al . , 2011 ) .
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 .
cephalopods in action . this is a multimedia appendix to published papers , that features video clips of cephalopods filmed from submersibles . included are :
the list of species featured in the videos , arranged as a taxonomic list , only relevant taxa included .
introducing an interactive key to the families of the decapodiformes . try this , it ' s exciting !
expedition journals from the search for the giant squid off new zealand , 1999 .
this page was created by jim felley , mike vecchione , clyde roper , mike sweeney , and tyler christensen . if you have questions or comments , contact mike vecchione .
férussac a . e . j . & d ' orbigny a . [ 1834 ] 1835 - 1848 . histoire naturelle générale et particulière des céphalopodes acétabulifères vivants et fossiles . pp . [ 1 - 96 ] , i - lvi , 1 - 361 , atlas with 144 plates . paris , baillière . , available online at urltoken page ( s ) : pl . 4 [ details ]
d ' orbigny [ in férussac & d ' orbigny ] , 1839–1842 . accessed through : world register of marine species at : urltoken ; = 141454 on 2018 - 07 - 09
gofas , s . ; le renard , j . ; bouchet , p . ( 2001 ) . mollusca . in : costello , m . j . et al . ( eds ) , european register of marine species : a check - list of the marine species in europe and a bibliography of guides to their identification . patrimoines naturels . 50 : 180 - 213 . ( look up in imis ) [ details ]
reid , a . & jereb , p . ( 2005 ) . family sepiolidae . pp . 153 - 203 , in p . jereb & c . f . e . roper eds . cephalopods of the world . an annotated and illustrated catalogue of cephalopod species known to date . volume 1 . chambered nautiluses and sepioids ( nautilidae , sepiidae , sepiolidae , sepiadariidae , idiosepiidae and spirulidae ) . fao species catalogue for fishery purposes [ rome , fao ] . 4 ( 1 ) : 262 pp . 9 pls . page ( s ) : 159 [ details ]
length up to 21 mm mantle length ( mature males and females similar in size ) . [ details ]
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has been assessed as data deficient because little information is available on fishing take . although it is not targeted by commercial fisheries , it is probably caught locally and until more data are available the impact of such take cannot be assessed .
this species occurs from iceland and faroe islands in the north to morocco in the south ( reid and jereb 2005 ) . its distribution includes western norway , the united kingdom and ireland , the north sea and the west coast of europe ( reid and jereb 2005 ) . it may also occur in the mediterranean sea ( ligurian sea ) ( reid and jereb 2005 ) .
males and females attain similar body sizes ( 21 mm in mantle length ) . this small species occurs from shallow water to the upper continental slope , although associated with the benthos it has been collected from the water column during the day as well as at night ( reid and jereb 2005 ) . this species has a light organ ( norman 2003 ) . mature males have enlarged suckers and a fleshy bulb on the tip of their left first arm ( norman 2003 ) . off scotland ( firemore bay ) spawning appears to occur throughout the year with peaks in april and july to august ( reid and jereb 2005 ) . members of the subfamily sepiolinae are bottom living species that typically bury in soft sediments during the day , and emerge at night to feed ( norman 2003 ) .
this species is probably caught in local fisheries ( reid and jereb 2005 ) .
this species is probably caught in small - scale local fisheries ( reid and jereb 2005 ) .
there are no conservation measures in place , but currently there is no evidence that specific conservation measures are required . further research is recommended regarding the population trends , distribution , life history traits and threats impacting this species .
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at proximal end of dorsal series , 3 slightly enlarged suckers with swollen pedicles , followed by 3 - 5 very small suckers with swollen pedicles , then 3 - 5 greatly enlarged suckers about midway out arm .
copulatory apparatus at base of hectocotylus with large swollen horn with secondary lobes basally .
tips of each arms iv with 4 - 8 series of minute suckers ; proximal to tip , suckers in two series .
tentacular club with 8 sucker series with suckers in dorsal series larger than those in ventral series .
integumental band of fusion between head and mantle 33 - 50 % of head width .
photophores similar to those of most sepiolids with pair of bean - shaped reflectors backed by thin , ink sac ; crypt containing luminescent bacteria deeper in viscera and between reflectors .
bursa copulatrix in mature females relatively small , located on left side of mantle cavity , without expansion toward right side , and behind left nidamental gland .
the female seems to initiate mating by swimming in front of the male . the male grabs the female in the midventral region of her mantle then shifts to grasp the female ' s neck with the third arm pair and insert the dorsal arms into the female ' s mantle cavity . the left dorsal arm ( hectocotylus ) presumably passes the spermatophores to the female .
hatchlings vary in size from about 1 . 1 - 1 . 7 mm ml ( rodrigues , et al . , 2010 ) . hatchlings and juveniles are , in gereral , similar in appearance to adults except for relatively smaller arms and tentacles .
guerra , a . 1992 . mollusca , cephalopoda . in : ramos , ma et al . , ( eds ) . fauna ibérica , vol1 . museo nacional de ciencias naturales . csic . madrid , 327 pp .
guerra , a . 2012 . cephstock ( cephalopod stocks in european waters . review , analysis , assessment and sustainable management ) . ices working group on cephalopods . in press .
jereb , p . and roper , c . f . e . ( eds . ) 2005 . cephalopod of the world . an annotated and illustrated catalogue of cephalopod species known to date . vol 1 . chambered nautiluses and sepioids . fao species catalogue for fishery purposes no 4 , vol . 1 , rome , fao .
guerra a . 1992 . mollusca , cephalopoda . in : ramos , ma et al . , ( eds ) . fauna ibérica , vol1 . museo nacional de ciencias naturales . csic . madrid , 327 pp .
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m . j . de kluijver , s . s . ingalsuo & r . h . de bruyne
length about 20 mm , comprising about half of the total body - length .
fins are thin and delicate , each as broad as body at point of attachment , irregularly rounded .
from iceland , faeroe islands and western norway to morocco . absent from the mediterranean sea .
hayward , p . j . , wigham , g . d . & n . yonow , 1990 . mollusca i : polyplacophora , scaphopoda , and gastropoda . in : the marine fauna of the british isles and north - west europe . ( ed . p . j . hayward & j . s . ryland ) . clarendon press , oxford : 628 - 730 .
nesis , k . n . , 1987 . cephalopods of the world . t . f . h . publications , inc . , ltd .
seaward , d . r . , 1990 . distribution of the marine molluscs of north west europe . nature conservancy council .
step , e . , 1927 . shell life . 421 pp . frederick warne & co . , ltd , london .
a plump , rounded cuttlefish small in size of up to 6 cm , with rounded fins that do not run along its entire length . the colour varies from black - brown to pale dorsally and pale ventrally . it is rarely striped .
found around much of the english and scottish coastline and in a few locations in wales . also found to the east and south coasts of ireland .
often found in rockpools , subtidally and offshore . swims over or burrows in sand and gravel .
colour - very variable , black - brown to pale dorsally , usually pale ventrally .
campbell , a . , 1994 . seashores and shallow seas of britain and europe . london : hamlyn .
hayward , p . , nelson - smith , t . & shields , c . 1996 . collins pocket guide . sea shore of britain and northern europe . london : harpercollins .
howson , c . m . & picton , b . e . , 1997 . the species directory of the marine fauna and flora of the british isles and surrounding seas . belfast : ulster museum . [ ulster museum publication , no . 276 . ]
miramand , p . & bentley , d . , 1992 . concentration and distribution of heavy metals in tissues of two cephalopods , eledone cirrhosa and sepia officinalis , from the french coast of the english channel marine biology , 114 , 407 - 414 .
roper , c . f . e . , sweeney , m . j . & nauen , c . e . , 1984 . fao species catalogue . vol . 3 . cephalopods of the world . an annotated and illustrated catalogue of species of interest to fisheries . fao fisheries synopsis , 125 , 3 , 277 .
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a plump , rounded cuttlefish small in size with rounded fins that do not run along its entire length . the colour varies from black - brown to pale dorsally and pale ventrally . it is rarely striped .
lu , c . c . , r . boucher - rodoni and a . tillier
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 )
taxon validity : [ fide nesis ( 1987a : 132 ) ] . repository : mnhn syntype 2 - 1 - 1209 [ fide lu et al . ( 1995 ) ] . type locality : english channel [ fide lu et al . ( 1995 ) ]
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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finds sub - sequence or patterns in the sequence and highlights the matching region . the tool works with standard single letter nucleotide or protein codes including ambiguities and can match prosite patterns in protein sequences . more . . .
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) . information on reproductive strategies may lead to a better understanding of the evolution of life histories , both reproductive strategies and life cycles being genetic adaptations to optimize the use of ecological niches in direct competition with other species and in response to environmental conditions ( rocha et al .
) . the patterns of ovulation and spawning are basic elements to characterize cephalopod reproductive patterns .
ovulation patterns may be distinguished according to oocyte formation and development and are strongly correlated with spawning patterns ( see rocha et al .
. according to these authors , spawning in the former pattern is monocyclic and eggs are laid in separate batches , with somatic growth continuing between separate events . the intermittent terminal spawning differs from multiple spawning in that somatic growth does not take place between spawning events .
field data on spawning and eggs are difficult to obtain and often difficult to interpret , due to the type of spawning pattern ( rocha et al .
) . therefore , direct observations on aquarium - kept females can be instructive and have been recorded for decades ( e . g . bello and deickert
) in the west coast of scotland . although this species was considered to be a resident species , the authors were not able to find egg masses . the only report of egg masses in british waters is by bidder ( in rees
ellis and solander 1786 . unfortunately , this paper provides little information on egg size , actual fecundity , spawning pattern , spawning clutch size , and time of spawning in
spermatophores are transferred to females and stored in the bursa copulatrix , a large pouch lying on the visceral mass that allows the spermatangia to become attached ( rodrigues et al .
) . they can remain there for long periods of time until eggs are laid and fertilized . fertilization is probably achieved when eggs transverse the bursa copulatrix ( hanlon and messenger
) . it is thus interesting to check whether females stop spawning once spermatangia have been used up .
) , and the analyses are based on the three factors considered by these authors : type of ovulation , spawning pattern , and growth vs . lack of growth between egg - laying events . additionally , we have introduced novel characters in the analysis such as egg clutch , egg size , and indexes to assess the reproductive allocation that allow us to discuss ecological features of the spawning strategy in greater detail .
this investigation was carried out between march 2008 and july 2009 . a total of 12 adult females were collected by scuba diving during several field trips in the ría de vigo ( 42°14′n ; 8°47′w ) , nw iberian peninsula . depth of collections ranged from 3 . 5 to 8 m , and the seabed was sandy with the presence of ripplemarks and without algal cover .
live specimens were immediately and carefully transported to the marine station of the university of vigo in toralla island ( ecimat - uvigo ) . each individual was placed in a 10 . 2 l ( 30 cm long × 18 cm wide × 19 cm deep ) glass tank with an open system of running seawater . water temperature in the tanks ranged between 13 and 19 . 5°c . the system received natural photoperiod according to the season . the bottom of the tanks was covered with a thin ( 1–2 cm ) layer of fine sand , taken from the same locality where the specimens were collected . all tanks were provided with local bivalve shells to serve as a substrate for egg deposition . females were always kept in isolation in the tanks and were never exposed to males in captivity , but all of them produced eggs that initiated development , thus indicating that spermatangia were present in the females .
bobtail squids were fed daily ad libitum with adults of the local mysid shrimp siriella armata . after the first episode of egg laying and up to death , the bobtail squids were offered ten s . armata daily , and intake was controlled daily . feeding rate was calculated according to choe ( 1966 ) : fr = [ f / ( t bw ) ] × 100 , where fr is the feeding rate ( percentage per day ) , f is total food consumed in wet weight , bw is body weight , and t is the number of days .
daily routine controls were undertaken between 09 : 00 and 10 : 00 a . m . , allowing to record for each individual : egg number per clutch , spawning duration ( time from first to last egg laid ) , actual fecundity ( af = total number of eggs laid by a female ) , and food intake during spawning . daily controls were carried out until death , up to 20 days after the first egg - laying episode . spawning was observed in different months during the current study , and no preference was observed in terms of spawning season .
specimens were measured for dorsal mantle length ( ml ) to 0 . 01 mm accuracy , weighed ( bw ) to 0 . 00001 g immediately after death , and subsequently preserved in 70 % etoh . all dissections were made on preserved specimens .
all immature and mature oocytes from the ovary and the proximal oviduct were counted and measured along the major axis using a stereomicroscope ( nikon smz - 1500 ) directly connected to a computer with an image analyzer ( nikon , nis - elements ) . based on indications given by mangold - wirz (
) , oocytes were assigned to four classes , depending on their stage of development : ( 1 ) early follicle oocytes ( small , 0 . 09–1 . 67 mm ) ; ( 2 ) late follicle oocytes without striated surface ( medium , 1 . 68–2 . 53 mm ) ; ( 3 ) yolky oocytes with white and striated surface ( large ) ; and ( 4 ) mature oocytes with smooth surface and orange in color . the size of the two last categories ranged from 2 . 54 to 3 . 75 mm .
the potential fecundity ( pf ) was expressed as the sum of the numbers of oocytes in the ovary and the oviduct plus the number of eggs already spawned . for assessing the reproductive allocation for each female , we determined two indexes : ( 1 ) the relative egg capsule length ( rel ) , which was calculated as the ratio between mean egg capsule length in the major axis and ml , and ( 2 ) the relative egg capsule weight ( rew ) as the ratio between mean egg capsule weight and bw .
additionally , after the last laying episode , all eggs were carefully removed from the substrate , measured , and weighed as indicated above . the egg volume was approximated using the formula for the volume of a prolate ellipsoid , ( 4 / 3 ) πlw
before females started to spawn , they were maintained in captivity between 51 and 137 days . unfortunately , no spawning event was directly observed . all spawning episodes took place at night . the females were always found dying or already dead in the morning . the observations of the timing of spawning events and spawning duration in the 12 studied females are shown in table
. the females did not take care of their egg clutches after spawning . no female survived more than a day after the last egg - laying event , and death does not seem to be related to the exhaustion of reproductive potential ( table
a , b ) . the capsules were laid either in a single layer or piled up into clusters of several layers . in all observed spawning events , the first egg batches were deposited at the water surface of the tank , and the following batches were attached to the walls of the tank , to the pvc pipe ( drain ) , or to the sandy bottom ( fig .
c ) , but never to the presented bivalve shells . sometimes these batches were deposited on the top of previously laid batches and occasionally above the water surface . individual batches contained between 1 and 89 eggs ( table
) . in all females , we observed multiple egg batches laid at intervals of roughly 1–8 days . in 11 of 12 females , the first batch of eggs was the largest one . after the second batch , the number of laid eggs was reduced in all females .
) laid some incompletely encapsulated eggs . this phenomenon always occurred in the last two batches of eggs .
no female fasted during spawning . food intake during spawning was between 0 . 14 and 0 . 29 g day −1 ( mean 0 . 22 ± 0 . 05 g day −1 ) or between 12 . 5 and 31 . 1 % bw day −1 ( mean 21 . 7 % ± 6 . 3 bw day −1 ) . no dissected female showed spermatangia attached in the bursa copulatrix .
) . this was revealed through the mature oocytes , represented as af , that have been spawned , while another group of oocytes is represented by small protoplasmic oocytes in the ovary of spent females ( harman et al .
) . post - spawning females exhibited eggs in different stages of protoplasmic growth and yolk accumulation , with a predominance ( 71 . 7–93 . 0 % ) of small oocytes of 0 . 09–1 . 68 mm ( table
) . the size of immature oocytes ( small , medium and large ) varied between 0 . 09 and 3 . 75 mm ( mean 0 . 8 7 ± 0 . 55 mm ) . of the 12 spawning females , 10 contained up to 28 mature oocytes in the oviduct at death ( table
) , varying in size between 2 . 68 and 3 . 75 mm ( mean 2 . 75 ± 0 . 44 mm ) . the largest oocytes were found in the largest females .
) . rel ranged from 16 up to 23 % ml ( mean 19 ± 2 % ml ) . the females incorporated ( rew ) between 0 . 37 and 1 . 58 ( mean 0 . 79 ± 0 . 36 % bw ) times their bw into reproductive material spawned ( laid eggs ) . the number of laid eggs did not show any correlation with the number of oocytes , and mature ova remained within the ovary (
> 0 . 05 ) . the size of the egg capsules in the major axis was 1 . 75–4 . 92 mm ( mean 2 . 75 ± 0 . 44 mm ) .
) . the regression equation was : ml = 8 . 8256 + 0 . 0746 ev . the weights of laid eggs ranged between 0 . 0036 and 0 . 0252 g ( mean 0 . 0072 ± 0 . 0041 g ) . of the best - fit , ml against
) . the regression equation was : ml = 1883 . 4ew − 140529 . 7ew
) . to avoid any disturbance of spawning behavior , in the present study , no measurements were performed to find out whether there is somatic growth between egg batches .
the presence of different - sized oocytes in the ovary indicated that the ovulation pattern is group - synchronous in this species . presence of oocytes in different stages of maturity in
2 . 5–3 . 0 mm , respectively . as no size distributions were given in the latter study , a proper comparison cannot be made . on the other hand , this study showed that females of
) , and that each batch of eggs might represent the daily production of mature oocytes or an appropriate time lapse between egg batches . this production decreased throughout the spawning period until death . however , the fact that
can lay multiple batches of eggs at least over a period of 20 days does not prove that this capacity is always fully exploited under natural conditions . moreover , as reproduction requires considerable allocation of energy , the presence of a relatively small number of medium and large oocytes in the ovary ( table
) could suggest that the energy provided through food intake was directed toward egg formation , while somatic growth did not take place , which is characteristic of this spawning strategy . however , results on some other species of bobtail squid suggest the opposite , i . e . a continuing increase in female body size once spawning has been initiated ( bello and deickert
we did not find spermatangia attached to the bursa copulatrix in any female after death , but mature ova were observed in the ovary , indicating that adult females may stop laying eggs once the spermatangia have been used up . the fact that eggs were deposited without exposing the isolated females to males indicates that females do not require the presence of males to lay eggs . little is known on mating systems and social interactions between male and female bobtail squids ( hanlon and messenger
deposited eggs on different substrates available in the tank . a similar finding was reported by boletzky et al . (
deposited a larger number of eggs on the sand bottom , as observed in this study . in the same way , arnold et al . (
( present study ) is the deposition of eggs on the top of previous batches . however , in the former species , there was no information on whether the eggs were exposed to air as observed in
. the deposition of eggs in multiple clutches and in different locations makes respective field studies difficult ( no sepiolid eggs were found in any of our dives ) and stresses the importance of laboratory observations .
) , we did not find any correlation between egg size and clutch size , suggesting that female size is the main determinant of egg size .
) observed a tendency of egg volume increasing with female body size for eight species of sepiolinae . this was also observed in s
the relationship between female ml , egg volume , and egg weight found in this study has an interesting evolutive consequence . as maternal size increases , more reserves can be allocated to each egg , increasing the volume or weight of eggs . as a result , there may be direct effects of maternal size on individual offspring and consequently on the trade - off between defence and offspring survivorship ( gabel - deickert
) . as known from other taxonomic groups ( e . g . , thrips ; kranz
) , these features are very important in sexual selection . more data are needed to address this problem .
the authors appreciate the valuable help by cristian aldea ( foundation cequa , chile ) and francisco rocha ( department of ecology and animal biology , university of vigo ) . special thanks to gonzalo giribet ( harvard university ) and fiona read ( ecobiomar iim / csic ) for useful discussions improving the manuscript . the first author was supported by a scholarship from the consellería de educación e ordenación universitaria da xunta de galicia .
. in : boyle pr ( ed ) cephalopod life cycles . species accounts , vol 1 . academic press , london , pp 75–91
beyer wh ( 1987 ) crc standard mathematical tables , 28th edn . crc press , boca raton
boletzky sv ( 1975 ) the reproductive cycle of sepiolidae ( mollusca , cephalopoda ) . pubbl staz zool napoli 39 ( suppl ) : 84–95
boletzky sv ( 1998 ) cephalopod eggs and egg masses . oceonogr mar biol annu rev 36 : 341–371
boletzky sv , boletzky mvv , frösch d , gätzi v ( 1971 ) laboratory rearing of sepiolinae ( mollusca : cephalopoda ) . mar biol 8 : 82–87
goulden ce , henry l , berrigan d ( 1987 ) egg size , postembryonic yolk , and survival ability . oecologia 72 : 28–31
guerra a ( 1992 ) mollusca , cephalopoda . in : ramos ma ( ed ) fauna ibèrica i . museo nacional de ciencias naturales csic , madrid
hanlon rt , messenger jb ( 1996 ) cephalopod behaviour . cambridge university press , uk
: a model system for bacteria - animal symbiosis . biol bull 192 : 364–374
kranz bd ( 2005 ) egg size and reproductive allocation in eusocial thrips . behav ecol 779–786
lessels cm ( 1991 ) the evolution of life histories . in : krebs jr , davies nb ( eds ) behavioural ecology : an evolutionary approach . blackwell scientific publications , oxford , pp 32–65
mangold - wirz k ( 1963 ) biologie des cephalopods benthiques et nectoniques de la mer catalane . vie milieu 13 : 1–285
nigmatullin chm ( 2002 ) ovary development , potential and actual fecundity and oocyte resorption in coleoid cephalopods : a review . berl palaeobiologische abh 1 : 82–84
rees wj ( 1957 ) mollusca : cephalopoda . in : plymouth marine fauna , 3rd edn . marine biological association of united kingdom , plymouth , pp 339
reid a , jereb p ( 2005 ) family sepiolidae . in : jereb p , roper cfe ( eds ) cephalopods of the world . an annotated and illustrated catalogue of species known to date i . chambered nautiluses and sepioids ( nautilidae , sepiidae , sepiolidae , sepiadariidae , idiosepiidae and spirulidae ) . fao species catalogue for fishery purposes , rome , pp 153–203
rocha f , guerra a , gonzález af ( 2001 ) a review of reproductive strategies in cephalopods . biol rev 76 : 291–304
svensson e , sinervo b ( 2000 ) experimental excursions on adaptive landscapes : density - dependent selection on egg size . evolution 54 : 1396–1403
van moorsel g ( 2004 ) dwerginktvissen ( sepiolidae ) in nederland . het zeepard 64 : 78–91
( mollusca : cephalopoda ) in the shallow sublittoral . j mar biol assoc uk 76 : 733–748
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zoe e . squires , mark d . norman , devi stuart - fox ; mating behaviour and general spawning patterns of the southern dumpling squid euprymna tasmanica ( sepiolidae ) : a laboratory study , journal of molluscan studies , volume 79 , issue 3 , 1 august 2013 , pages 263–269 , urltoken
we provide the first detailed description of mating behaviour and multiple mating in the southern dumpling squid , euprymna tasmanica ( pfeffer , 1884 ) in the laboratory , as well as details on their general spawning patterns . we found that male e . tasmanica increase the number of ‘pumps’ ( mantle contractions ) when mating with females that had recently mated , showing that males are able to determine the recent mating history of females . we also found that at the conclusion of mating , the male ' s hectocotylus was enlarged . to our knowledge , neither had previously been described in sepiolid squid . euprymna tasmanica females lay multiple clutches over a large proportion of their lifespan , from 1 to 121 d . there was a considerable variation in the number of eggs produced per female in captivity , ranging from 6 to 646 eggs , and in the number of eggs per clutch , from 6 to 163 eggs . egg number per clutch declined significantly over the spawning period . larger females produced larger hatchlings , and egg mass and hatchling mass were significantly correlated . at higher ambient water temperatures the rate at which females produced clutches increased and the size of the eggs laid decreased .


tyrannophryne pugnax , the tyrant devil is a species of deep-sea anglerfish in the dreamer family , oneirodidae .

it is the sole member of its genus .

like other oneirodids , t. pugnax is a bathypelagic fish with a bioluminescent lure .

it is known only from two adolescent female specimens , one caught in 1928 near tahiti-rarotonga , and the other in 1956 northwest of bikini atoll .

the most distinctive feature of t. pugnax is its extremely long lower jaw , the joint of which extends backwards well past the base of the pectoral fin .

the body of the fish is relatively slender , naked , and entirely black in color .

the tail fin has unpigmented rays and is covered by dark skin for some distance past its base .

the sphenotic spines ( above the eyes ) and symphysial spine ( at the tip of the jaw ) are present .

tyrannophryne pugnax

tyrannophryne pugnax : tyrannophryne pugnax is a species of deep - sea anglerfish in the dreamer family , oneirodidae . it is the sole member of its genus . more
the pugnaceous dreamer tyrannophryne pugnax , with a short rod and lure above the eyes .
tyrannophryne pugnax . . . tyrannophryne pugnax is a species of deep - sea anglerfish in the dreamer family , oneirodidae . . . pugnax is a bathypelagic fish with a bioluminescent lure . . . pugnax is its extremely long lower jaw , the joint of which extends backwards well past the base of the pectoral fin . . .
tyrannophryne pugnax is a species of deep - sea anglerfish in the dreamer family , oneirodidae . it is the sole member of its genus . like other oneirodids , t . pugnax is a bathypelagic fish with a bioluminescent lure . more
tyrannophryne pugnax on fish mapper tsn 623187 ( taxonomic serial number ) retrieved on from the integrated taxonomic information system online database . this is a cached copy . more
auricula meretricula - story . . . pugnax then arrives to claim auricula in scene vi . . . in scene vii , pugnax , trying to find auricula , finds dolia instead . . . dolia then fools pugnax into loving her , thereby saving auricula ' s and marcus ' s relationship , or so it seems . . .
penang betta . . . the penang betta ( betta pugnax ) , common name giant betta , is a species of freshwater spiked rayed fish in the gourami family ( osphronemidae ) of order perciformes . . . pugnax , as a natural predator of mosquito larvae , has found use in mosquito control effots . . . pugnax was well known as a fighting fish , attracting the interest of scientists studying animal behaviour at least as long ago as the 1880s . . .
greek , ' tyrranos ' or latin , ' tyrannus ' = tyrant + greek , ' phryne ' = toad ( to mean
tyrannical toad
in reference to its menacing look ; common name derived from type species t . pugnax ) ( ref . 86949 )
because several genera are known from very few specimens ( only two adolescent females in tyrannophryne , chirophryne , and puck ) , and for many , larvae and males are unknown , the following keys to females and males , both modified from bertelsen ( 1951 : 74 - 76 ) and pietsch ( 1974a : 30 ) , are tentative and may not include the best diagnostic characters .
marine ; bathypelagic ; depth range 400 - 2100 m ( ref . 86949 ) . deep - water
pacific ocean : eastern central pacific ( ref . 40966 ) ; western and central pacific , including south pacific ( ref . 86949 ) .
dorsal soft rays ( total ) : 5 ; anal soft rays : 5 . metamorphosed females distinguished by having an extremely large oblique mouth ; elements of upper and lower jaws extending posteriorly far beyond the base of the pectoral fin and opercular opening ; vomerine teeth present or absent ; well developed sphenotic spines ; well - developed symphisial spine on lower jaw ; elongate and tapering angular , forming long narrow spine ; hypomandibula with two heads ; small quadrate spine , however , longer than articular spine ; deeply notched posterior margin of opercle ; short and broad subopercle , dorsal end rounded , ventral end nearly circular ; toothless pharyngobranchial ii ; caudal fin lacking internal pigmentation ; extremely short illicium , almost totally enveloped by tissue of esca in smaller specimens ; well developed first ray of dorsal fin ; dorsal fin rays 5 ; anal fin rays 5 ; short and broad pectoral fin lobe , shorter than longest rays of pectoral fin ; pectoral fin rays 18 - 20 ; skin naked , lacking dermal spinules ; darkly pigmented skin of caudal peduncle extends well past base of caudal fin ( ref . 86949 ) .
nielsen , j . g . , 1974 . fish types in the zoological museum of copenhagen . zoological museum of copenhagen , denmark . 115 p . ( ref . 38022 )
) : 3 . 4 - 5 . 3 , mean 4 . 5 ( based on 371 cells ) .
phylogenetic diversity index ( ref . 82805 ) : pd 50 = 1 . 0000 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .
bayesian length - weight : a = 0 . 01000 ( 0 . 00244 - 0 . 04107 ) , b = 3 . 04 ( 2 . 81 - 3 . 27 ) , in cm total length , based on all lwr estimates for this body shape ( ref . 93245 ) .
trophic level ( ref . 69278 ) : 3 . 8 ±0 . 6 se ; based on size and trophs of closest relatives
resilience ( ref . 69278 ) : high , minimum population doubling time less than 15 months ( preliminary k or fecundity . ) .
vulnerability ( ref . 59153 ) : low to moderate vulnerability ( 30 of 100 ) .
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the root of the current tree connects the organisms featured in this tree to their containing group and the rest of the tree of life . the basal branching point in the tree represents the ancestor of the other groups in the tree . this ancestor diversified over time into several descendent subgroups , which are represented as internal nodes and terminal taxa to the right .
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the oneirodidae is by far the largest , most complex , and certainly the least understood family of the suborder . with 16 genera and 62 species , it contains nearly 40 % of all recognized ceratioids . of the 16 genera , five are currently represented by only one , two , or three adolescent or adult females ; only eight are represented by more than a dozen females . males have been described for only seven genera , while larvae are known for only eight . but despite the rareness of most recognized taxa , new oneirodids are continually being described .
metamorphosed females of the family oneirodidae are distinguished from those of all other ceratioid families by having the following combination of character states : supraethmoid present ; frontals widely separated ; parietals present ; sphenotic overlapped by anterolateral projection of pterotic ; metapterygoid and mesopterygoid present ; hypohyals 2 ; branchiostegal rays 6 ( 2 + 4 ) ; angular and preopercular spines absent ; jaws equal anteriorly ; postmaxillary process of premaxillae absent ; anterior - maxillomandibular ligament well developed ; pharyngobranchial iv absent ; a single ossified basibranchial ; ceratobranchial teeth absent ; epibranchial i free , not bound to wall of pharynx by connective tissue ; proximal one - fourth to one - half of ceratobranchial i bound to wall of pharynx , distal three - quarters to one - half free ; distal end of ceratobranchial i free , not bound by connective tissue to adjacent ceratobranchial ii ; proximal one - quarter to one - half of ceratobranchials ii - iv not bound together by connective tissue ; epurals absent ; hypural plate entire , without posterior notch ; pterygiophore of illicium bearing an ossified remnant of second cephalic spine ; escal bulb and central lumen present , esca without tooth - like denticles ; pectoral radials 3 ; dorsal - fin rays 4 - 8 ; anal - fin rays 4 - 7 , very rarely 3 ; pectoral - fin rays 14 - 30 ; caudal - fin rays 9 ( 2 simple + 4 bifurcated + 3 simple ) ; ovaries paired ; one or two small pyloric caecae present or absent .
lateral view of esca of oneirodes macrosteus . © 2005 e . a . widder
although not characteristic of all members of the family , the following additional features are important in differentiating the oneirodidae : each frontal with a prominent ventromedial extension ( absent in lophodolos ) ; sphenotic spines usually present ( absent in chaenophryne ) ; pterosphenoid usually present ( absent in lophodolos ) ; hyomandibular usually with a double head ( single head in bertella ) ; opercle bifurcate , dorsal fork supported by a single rib ( except in larval females of danaphryne ) ; anterior subopercular spine usually absent ( blunt projection present in most specimens of chaenophryne , adolescent females of lophodolos , and some larvae and males of dolopichthys and pentherichthys ) ; quadrate and articular spines usually well developed ( small to rudimentary in chaenophryne ) ; lower jaw usually with a well - developed symphysial spine ( small , blunt to absent in chaenophryne , absent in pentherichthys ) ; pharyngobranchial i usually absent ( present in spiniphryne and oneirodes ) ; pharyngobranchial ii usually well developed and heavily toothed ( reduced and toothless in bertella , microlophichthys , and some species of oneirodes ; absent in pentherichthys and lophodolos ) ; epibranchial teeth usually absent ( present on epibranchial i of some species of oneirodes ) ; ossified posteroventral process of coracoid usually absent ( present in spiniphryne and oneirodes ) ; pelvic bone usually rod - like , with or without slightly expanded distal tip ( triradiate or broadly expanded distally in chaenophryne ; pietsch , 1975 : 79 , fig . 2 ) ; dermal spinules usually absent ( well developed in spiniphryne , minute and widely scattered in oneirodes ) .
free - living males of oneirodids . a chaenophryne draco - group , 14 mm , zmuc p92686 ; b dolopichthys sp . , 12 . 5 mm , zmuc p92799 ; c microlophichthys andracanthus , 16 . 5 mm , zmuc p9293 ; d oneirodes sp . , 12 . 5 mm , zmuc p921016 ; e pentherichthys sp . , 13 mm , zmuc p921113 . ( all after bertelsen , 1951 , © 1951 bertelsen ) .
metamorphosed males are distinguished from those of all other ceratioid families in having the following combination of character states : eyes directed laterally , elliptical in shape , axis short , diameter of pupil greater than that of lens ; olfactory organs large , anterior nostrils situated close together and opening forwards ; posterior nostrils lateral , usually larger than eye ; nasal area usually pigmented , sometimes slightly inflated ; jaw teeth absent ; dermal spinules of snout absent ; posterior end of upper denticular remote from anterior end of pterygiophore of illicium ; fin - ray counts as given for metamorphosed females ; skin naked ( but males of the spiny - skinned oneirodid genus spiniphryne are unknown ) ; free - living , non - parasitic , with two exceptions , both apparently facultative couplings : a single known attached pair of leptacanthichthys gracilispinis and another of bertella idiomorpha ( see pietsch , 2005 ) .
there is no satisfactory combination of features that serve to adequately diagnose oneirodid larvae . as stated by bertelsen ( 1951 : 71 ) , it is “easier in practice to make the identification [ of larvae ] from the features characteristic of each of the many genera within the family . ” to a somewhat lesser extent , the same could also be said for the metamorphosed males and females .
color of females in preservative dark brown to black over entire external surface of body ( except for escal appendages and distal portion of escal bulb ) ; oral cavity and viscera , except for outer surface of stomach wall , unpigmented . metamorphosed males with outer pigmentation as for females , except nasal area often unpigmented ; subdermal pigmentation of males and larvae highly variable ( see bertelsen , 1951 : 73 ) .
the largest known female is a 370 - mm specimen of oneirodes heteronema , collected by the walther herwig during the 1982 expedition to the mid - atlantic ridge . the largest known male measures 16 . 5 mm .
the oneirodidae is widely distributed throughout the more productive waters of all three major oceans of the world . unlike some ceratioid families ( e . g . , melanocetidae ) , which appear to be limited by the arctic and antarctic polar fronts , oneirodids extend northward to at least 66º in the north atlantic and 62º in the bering sea , and southward into the southern ocean to at least 65ºs . it is represented in the caribbean sea and in the gulfs of aden , california , and mexico ; but , like all other ceratioids , it has not been collected in the mediterranean sea .
in the following key , slightly modified from bertelsen ( 1951 : 75 ) , it is uncertain how much diagnostic value can be ascribed to the number of denticular teeth and olfactory lamellae ; these presumably increase during adolescent development and therefore may be subject to greater individual variation than indicated here .
bertelsen , e . 1951 . the ceratioid fishes . ontogeny , taxonomy , distribution and biology . dana rept . , 39 , 276 pp .
garman , s . 1899 . reports on an exploration off the west coasts of mexico , central and south america , and off the galapagos islands , in charge of alexander agassiz , by the u . s . fish commission steamer
albatross ,
during 1891 , lieut . commander z . l . tanner , u . s . n . , commanding . xxvi . the fishes . mem . mus . comp . zool . , 24 , 431 pp .
lloyd , r . e . 1909 . a description of the deep - sea fish caught by the r . i . m . s . ship
investigator
since the year 1900 , with supposed evidence of mutation in malthopsis . mem . indian mus . , calcutta , 2 ( 3 ) : 139 - 180 .
lütken , c . f . 1871 . oneirodes eschrichtii ltk . en ny grønlandsk tudsefisk . oversigt over det kongl . danske vidensk . selsk . forhandl . , 1871 : 56 - 74 . [ in danish , french summary in the same volume , pp . 9 - 18 . ]
pietsch , t . w . 1969 . a remarkable new genus and species of deep - sea anglerfish ( family oneirodidae ) from off guadalupe island , mexico . copeia , 1969 ( 2 ) : 365 - 369 .
pietsch , t . w . 1972 . a second specimen of the deep - sea anglerfish , phyllorhinichthys micractis ( family oneirodidae ) , with a histological description of the snout flaps . copeia , 1972 ( 2 ) : 335 - 340 .
pietsch , t . w . 1973 . a new genus and species of deep - sea anglerfish ( pisces : oneirodidae ) from the northern pacific ocean . copeia , 1973 ( 2 ) : 193 - 199 .
pietsch , t . w . 1974a . osteology and relationships of ceratioid anglerfishes of the family oneirodidae , with a review of the genus oneirodes lütken . nat . hist . mus . l . a . co . , sci . bull . , 18 , 113 pp .
pietsch , t . w . 1974b . systematics and distribution of ceratioid anglerfishes of the genus lophodolos ( family oneirodidae ) . breviora , 425 : 1 - 19 .
pietsch , t . w . 1975 . systematics and distribution of ceratioid anglerfishes of the genus chaenophryne ( family oneirodidae ) . bull . mus . comp . zool . , 147 ( 2 ) : 75 - 100 .
pietsch , t . w . 1978 . a new genus and species of deep - sea anglerfish from the eastern north pacific ocean , with a review of the allied genera leptacanthichthys , chirophryne , and ctenochirichthys ( family oneirodidae ) . nat . hist . mus . los angeles co . , contrib . sci . , 297 : 1 - 25 .
pietsch , t . w . 2005 . dimorphism , parasitism , and sex revisited : modes of reproduction among deep - sea ceratioid anglerfishes ( teleostei : lophiiformes ) . ichthyol . res . , 52 : 207 - 236 .
regan , c . t . 1925 . new ceratioid fishes from the n . atlantic , the caribbean sea , and the gulf of panama , collected by the
dana .
ann . mag . nat . hist . , ser . 8 , 8 ( 62 ) : 561 - 567 .
regan , c . t . , and e . trewavas . 1932 . deep - sea anglerfish ( ceratioidea ) . dana rept . , 2 , 113 pp .
correspondence regarding this page should be directed to theodore w . pietsch at and christopher p . kenaley at
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pietsch , theodore w . 2005 . oneirodidae . dreamers . version 05 november 2005 ( under construction ) .
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the affinities of all the beings of the same class have sometimes been represented by a great tree . . . as buds give rise by growth to fresh buds , and these if vigorous , branch out and overtop on all sides many a feebler branch , so by generation i believe it has been with the great tree of life , which fills with its dead and broken branches the crust of the earth , and covers the surface with its ever branching and beautiful ramifications .
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pietsch , t . w . / carpenter , kent e . , and volker h . niem , eds .
fao species identification guide for fishery purposes : the living marine resources of the western central pacific , vol . 3 : batoid fishes , chimaeras and bony fishes , part 1 ( elopidae to linophrynidae )
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to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .
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a female fantail sea devil beckons you to
come to momma . . . .
.
being highly visual creatures adapted to a day active lifestyle , it is somewhat natural for us to think that all organisms are also out and about during the day and at rest at night .
that is not true - - - most of the terrestrial biological world is nocturnal .
it is not even true for terrestrial mammals , since 60 % of all living mammals are either bats or rodents , most of which are nocturnal .
furthermore , most of the living world does not even live on land . about 72 per cent of the earth’s surface is covered by oceans and the largest habitat on earth is the oceanic midwaters , the bathypelagic zone , which extends around the globe .
extending from 3300 – 13000 ft ( 1000 – 4000m ) , it is a cold world of perpetual midnight , where sunlight never penetrates , the pressures are crushing ( as great as 2 tons per square inch ) , oxygen levels are very low , and the temperatures are permanently near freezing .
yet in spite of these incredible challenges some organisms have adapted to and even flourished in that environment .
among the most bizarre denizens of the bathypelagic zone are the deep sea anglerfishes , boney fish collectively classified in the suborder ceratioidei . if you have never seen a deep sea angler , the following is an apt description :
“ the medieval imagination , rioting in strange imps and hobgoblins , could hardly have invented anything more malevolent in appearance than the ceratioids or deep - sea anglerfishes , sometimes called black devils . ”
high coefficients of weirdness . . . . representatives of the deep sea angler fishes .
there are 160 species in 11 families in the group , making it the most species diverse group of fish in the bathypelagic zone .
they’re not gigantic fish , large adults range from 4 - 10 inches ( 10 - 25 cm ) in length , although in one species adults have been captured close to 34 inches ( 86 cm ) in length . most are globular / spherical in shape , being little more than an enormous mouth and stomach with a tail . a few are oblong and even fewer elongated .
most feed in midwater but a few seem to feed at or near the bottom . the common names for these families are both descriptive and fascinating ; whipnose seadevils , needlebeard seadevils , fantail seadevils , dreamers , and footballfishes to name just a few
because of the absence of light there is no photosynthesis in the bathypelagic zone and the food chain is supported by the organic material that falls from higher up in the water column . with food at a premium and prey widely spaced , these fish have to save energy whenever possible .
so rather than actively seek out prey , they simply float in the water .
to float with the least effort these fish have many adaptations to reduce their specific gravity to mach their environment , thus preventing them for rising or sinking . among those specializations are loss of swim bladder , reduced body musculature , and a poorly ossified skeleton composed of very thin bones . without a need to actively swim , they have lost or reduced many fins and others are reduced in size .
radiograph of a deep sea anglerfish showing the lightly built skeleton , large mouth , and even larger stomach .
the first spine of the dorsal fin is modified and elongated , bearing a glowing organ at its tip .
the light is generated by colonies of bioluminescent bacteria living inside the swollen tip . most angler fish waves this structure back and forth like a fly fisherman ( hence their name ) to attract prey , although a few hold it stiff and vibrate it .
in some the structure is very short , only a stub , while in other species the spine is absolutely enormous , several times the fish’s body length .
the whipnose seadevil gigantactis macronema with a fishing rod five time longer than its body length .
some have additional glowing structures growing from the chin area , sometimes resembling a great , luminescent beard .
glowing above and below , the bearded seadevil linophryne arborifera with a bioluminescent lure and beard .
adults are fish eaters and with prey far and few between these predators must make the most out of each meal . once a prey item is close , the anglerfish quickly expands its immense mouth and gill chamber , instantly sucking the complete prey entirely into the mouth .
so their mouths are enormous and the stomach can be greatly extended to accommodate large prey items .
the bearded seadevil linophryne lucife r with a large fish visible in its expanded stomach .
over indulgence . a 112 mm long doublespine sea devil diceratias trilobus with a 369 + mm fish protruding from its mouth .
the sharp teeth in the mouth can fold backwards to let prey slide in more easily and erected to prevent prey from escaping .
lacking scales , oxygen can be absorbed directly through the skin . because water cannot be compressed very much angler fish are globular and contain large amounts of water . this enables them to resist the great pressures they are subjected to . there are many other specializations , but these should suffice to introduce the group .
what is clear is that this most fascinating group is living proof of the jurassic park adage “ life will find a way . ”
the ghostly seadevil haplophryne molli s showing the many ceratioid adaptations to deep sea life : thin skeleton , large mouth , reduced fins , loss of scales , globular body , small eyes .
they are wide dispersed in their environment . few have been observed alive in their natural habitat . most specimens have been collected in trawls sampling at great depths and because of the immense changes in temperature and pressure as the trawl comes up from depth , fish do not survive the journey . thus they have rarely been observed alive in the lab and none have been kept permanently alive and studied long term in captivity . however , rare video of living fish filmed at depth can be viewed at
given these difficulties , it is surprising that the first specimen was collected in 1833 , when it was found washed ashore on the coast of greenland , and described in a scientific publication in 1837 .
given that they are small , fragile , and live at mid water depth far out in the ocean basins , one might expect deep sea anglers to have no fossil record .
it is limited and the fossils are rare , but they have been found .
well the fossils are found in turbidites , deposits that form as a result of underwater avalanches transporting vast amounts of sediment into the deep ocean , trapping , carrying along and burying anything caught in the flow .
earthquakes can trigger that large scale movement of sediment over the edge of the continental shelf out into the basin that become turbidite deposits .
given the right location and geological history , these deep sea deposits can be found at the surface .
one of those areas is the puente formation near los angeles . two fossil ceratioid sites have been found in this formation , close to los angeles . both were discovered during construction activities , one for the construction of the metro rail red line , wilshire boulevard / vermont avenue subway station .
the puente formation is upper miocene in age , about 9 million years old , indicating that once well adapted to their hostile and eternally dark world , deep sea anglers have undergone little morphological evolution .
because of their delicate skeletons the fossils are sometimes hard for the untrained eye to see clearly in the rock , so here i show just the best specimen from the puente fm . but it is spectacular !
in reading the scientific papers describing these fossils , one notices that the authors repeatedly identify the specimens as females .
no males have ever been found . why is that and how do paleontologists know with so much certainty that these 9 million year old fish fossils are all of females ?
sometimes it is easy to see , such as the colorful fan tail of male peacocks or different color patterns seen in many birds .
sometimes it is behavioral , where males and females live in different areas and come together for breeding .
sometimes it is in the skeleton , the pelvis in adult male and female humans are different and those differences are related to giving birth .
when it come to fossil vertebrates , however , things are often not so clear .
there are places where soft tissue preservation can reveal the nature of the reproductive system making sex identification fairly straight forward .
from montana when they discovered , in the leg bone , preserved medullary bone , a type of tissue found in present - day female birds only during the period when eggs are laid .
theropods , the carnivorous dinosaurs , are a group that much of my research focuses on . in a few rare instances , a large number of skeletons are preserved in a single quarry . in those cases , for any given size we can see two morphs , one that is lightly built and gracile and another that is massive and more robust . in modern day hawks , eagles , and falcons a similar pattern of gracile / robust morphs is seen and it is the female that has the more robust build . we can extend this from hawks to other theropods , but there is some uncertainty and we have no independent data to support it . we cannot completely rule out that the larger morph is actually the male in these fossils .
in other cases , sexual dimorphism is evident but interpreting it is very difficult . i , along with drs . george engelmann ( university of nebraska ) and brooks britt ( brigham young university ) are currently describing new fossil reptiles belonging to a group known as drepanosaurs . these are very peculiar beasts and their skeletal morphology presents us with many puzzles . however , there are some truly remarkable , and wholly unexpected , differences between specimens when it comes to foot structure . the skeletons all belong to the same species and come from the same quarry where they were found lying side by side . we can make a strong case that what the differences we see are sexual dimorphism , but we have no idea which is male and which is female , much less why there should be such striking differences between the sexes in the foot and how this effected their biology . it is related to behavioral differences , ecological differences , or something else ? we just don’t know .
so sexing your fossil is not always easy often not even possible . but what is it that makes the identification of all know deep sea angler fish fossils as females so clear and irrefutable ? for the answer to that question we need to go back to the living members of the group .
living in the world of eternal darkness presents many problems . as discussed above , finding prey is clearly a major challenge . similar problems present themselves when trying to find a mate in the bathypelagic zone .
one of the striling features of deep sea angler fish is the pronounced sexual dimorphism in body size . this can be extreme , as in one species where the female is more than 60 times the length of the males and about half a million times as heavy . the natural question is why ? ? ?
males of living deep sea anglers find their mates in various ways . in some they have enlarged olfactory organs that allow them to sense the females , by following the phermones released by the females from the lure at the end of their “fishing poles . ”
some have large eyes and may find females by seeing their glowing lures , and some have both large eyes and large olfactory organs .
the small male of the bearded seadevil linophryne arborifera showing the large olfactory organs ( arrow ) by which it is able to locate females .
after finding and approaching a females , males follow two major strategies for mating , strategies that vary by species .
if she is nearly ready to reproduce and remains temporarily attached until spawning occurs . after that the male releases himself and searches for another female .
but in many deep sea anglers males have evolved an amazing mechanism for reproduction . in those species the male bite the female’s skin and never lets go , undergoing a remarkable transformation .
the skin of the male grows and fuses with the skin of the female .
in some cases a projection of the female’s skin completely blocks the mouth of the male .
their circulatory systems join and the male receives all his nutrients , already digested , from the female’s blood . because of this , the digestive system of the male atrophies .
however , his testes enlarge to great size . in return for food and a free ride the male becomes little more than a reproductive organ , contributing sperm when breeding season comes around .
this comes at some cost to the female but those costs are offset by not having to find a mate in the vastness of the bathypelagic realm .
female of the needlebeard seadevil neoceratias spinifer , with male attached near base of tail ( arrow ) .
usually there is one male per female , but in some species there are multiple males , sometimes as many as eight , attached to a single female .
drawing of a parasitic male warty seadevil ceratias holbelli showing the expansion of tissue around the head and its fusion with the female ' s body .
now there are some very interesting questions raised by this male sexual parasitism when it come to issues of how two different individuals fuse . how are hormonal and immunological issues overcome in order to prevent “tissue rejection” of the male by the female ?
this has promising medical implications for humans , such as rejection of transplanted organ .
but these fish live in the ocean deeps and no one has yet been able to keep them permanently alive to study in the laboratory .
thus the possible answer to human tissue rejection remains locked away in tiny fish living in a world of midnight and crushing pressure .
so sexing fossils of deep sea anglerfish is not as difficult as it might seem at first . we know that in all living species of this group the males are always much smaller than females and they are not just miniature versions of females . males are of quite different in shape ( lacking a lure , having a small mouth , and missing many of
) and frequently they are small , amorphous sacs attached to females . given this striking sexual dimorphism in all the living members of the group it is clear that all the known fossils must be females .
it ' s as easy as pie . an female chaeonphryne ( above ) can easily be differentiated from a male ( below ) . not to scale , female is ten times longer than the male .
so when a female ceratioid says “come to momma” to her mate he only needs to come once and he can stay for life . it’s like the life of riley , only without the couch , beer , and television . and for the female every day of breeding season is mother’s day – her mate is always there when she needs him .
dr . theodore pietsch , leading authority on deep sea angler fish , holding a large female . a
for those interested in learning more about ceratioid angler fish , the best place to start is pietsch 2009 , a remarkable and thorough summary of what is known about these fascinating creatures .
readable . there are hundreds of illustrations in the volume , including many beautiful color photos , of both the whole fish and details of their anatomy .
the various pietsch entries for the on - line tree of life project ( see sources below ) are shorter but still quite informative .
when i was just a kid in paterson , new jersey there was a branch library on one of the corners of my block .
it wasn’t a gigantic library , but i could get to it without crossing a street , so i visited often .
beebe reported his observations on many deep sea organisms , but the ones that stuck with me were those of deep sea anglers , whose glowing organs would mark their passage through the dark outside his windows .
beebe couldn’t collect specimens from the bathysphere , but he had color drawings made of what he saw .
those of the anglerfish were fascinating and really caught my attention . i never forgot those magical denizens of the deep and i have retained an interest in them up to the present day .
however , by the time i first saw beebe ' s book i was already severely infected with the dinosaur virus and had my heart set on becoming a paleontologist .
nothing , not even fish that looked like they came from another world , could change that trajectory .
beebe , w . 1934 . half mile down . harcourt , brace and company , n . y . : 344 pages ( available freely on - line at urltoken )
beebe , w . 1938 . ceratias - - siren of the deep . through perpetual darkenss the tiny male seeks out his mate and attaches himself to her spiny skin for life . bulletin of the new york zoological society 41 : 50 - 53
carnevale , g . and pietsch , t . w . 2009 . the deep - sea anglerfish genus acentrophryne ( teleostei , ceratioidei , linophrynidae ) in the miocene of california . journal of vertebrate paleontology 29 ( 2 ) : 372–378
carnevale , g . , pietsch , t . w . , takeuchi , g . t . , and huddleston , r . w . 2008 . fossil ceratioid anglerfishes ( teleostei : lophiiformes ) from the miocene of the los angeles basin , california .
gregory , w . k . and conrad , g . m . 1936 . the evolution of the pediculate fishes .
pietsch , t . w . 1976 . dimorphism , parasitism and sex : reproductive strategies among deepsea ceratioid anglerfishes . copeia , 1976 ( 4 ) : 781–793 .
pietsch , t . w . 2005 . centrophrynidae . centrophryne spinulosa . prickly seadevils . version 03 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . diceratiidae . doublespine seadevils . version 05 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . melanocetidae . melanocetus . black seadevils . version 05 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . thaumatichthyidae . wolftrap seadevils . version 06 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . oneirodidae . dreamers . version 05 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . caulophrynidae . fanfin seadevils . version 03 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2006 . ceratiidae . warty seadevils . version 17 april 2006 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2007 . himantolophidae . himantolophus . footballfishes . version 02 october 2007 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005 . dimorphism , parasitism , and sex revisited : modes of reproduction among deep - sea ceratioid anglerfishes ( teleostei : lophiiformes ) . ichthyological research 52 : 207 - 236 .
pietsch , t . w . 2005b . neoceratiidae . neoceratias spinifer . needlebeard seadevils . version 06 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2005c . gigantactinidae . whipnose seadevils . version 06 november 2005 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . 2009 . oceanic anglerfishes : extraordinary diversity in the deep sea . university of california press , berkeley : 557 pages .
pietsch , t . w . and p . kenaley , c . p . 2007 . ceratioidei . seadevils , devilfishes , deep - sea anglerfishes . version 02 october 2007 ( under construction ) . urltoken in the tree of life web project , urltoken
pietsch , t . w . and lavenberg , r . j . a 1980 . a fossil ceratioid anglerfish from the late miocene of california , copeia 1980 ( 4 ) : 906 - 908 .
pietsch , t . w . and orr , j . w . 2007 . phylogenetic relationships of the deep - sea anglerfishes of the suborder ceratioidei ( teleostei : lophiiformes ) based on morphology .
regan , c . t . 1925 . dwarfed males parasitic on the females in oceanic angler - fishes ( pediculati , ceratioidea ) . proceedings of the royal society , b , 97 : 386–400 .
dan chure : i have been the paleontologist at dinosaur national monument for 34 years . my main research interests are dinosaurs & the ecosystems they lived in . i am also interested in fossil resource management & preservation , & the impacts of 20th century warfare and social revolutions on fossil collections & scientists . this blog is personal and not an official blog of dinosaur national monument or the national park service .
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