Velvet belly lanternshark

{{Short description|Species of shark}} {{Speciesbox | status = VU | status_system = IUCN3.1 | image = Velvet Belly Lanternshark.jpg | genus = Etmopterus | species = spinax | range_map = Etmopterus spinax distmap.png | range_map_caption = Range of the velvet belly lantern shark | authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]]) | synonyms = *''Etmopterus aculeatus'' Rafinesque, 1810 *''Spinax gunneri'' Reinhardt, 1825 *''Spinax linnei'' Malm, 1877 *''Spinax niger''* Cloquet, 1816 *''Spinax vitulinus''* de la Pylaie, 1835 *''Squalus infernus'' Blainville, 1825 *''Squalus niger'' Gunnerus, 1763 *''Squalus spinax'' Linnaeus, 1758 ---- * ambiguous synonym |status_ref=<ref name="iucn status 19 November 2021">{{cite iucn |author=Finucci, B. |author2=Derrick, D. |author3=Dia, M. |author4=Ducrocq, M. |author5=Neat, F.C. |author6=Pacoureau, N. |author7=Serena, F. |author8=VanderWright, W.J. |date=2021 |title=''Etmopterus spinax'' |volume=2021 |article-number=e.T161388A124475610 |doi=10.2305/IUCN.UK.2021-2.RLTS.T161388A124475610.en |access-date=19 November 2021}}</ref> }}

The '''velvet belly lanternshark''' (or simply '''velvet belly''') ('''''Etmopterus spinax''''') is a species of [[Squaliformes|dogfish shark]] in the [[Family (taxonomy)|family]] [[Etmopteridae]]. One of the most common deepwater sharks in the northeastern [[Atlantic Ocean]], the velvet belly is found from [[Iceland]] and [[Norway]] to [[Gabon]] and [[South Africa]] at a depth of {{convert|20|-|2490|m|ft|abbr=on}}.<ref name=":0">{{Citation|title = 2015-12-15 - Velvet belly lanternshark/Etmopterus spinax and Rabbit fish/Chimaera monstrosa at 20 meters depth|url = https://vimeo.com/149070954|access-date = 2015-12-25}}</ref><ref name="jones et al" /> A small shark generally no more than {{convert|45|cm|in|abbr=on}} long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small [[gill slit]]s. Like other [[Etmopterus|lanternsharks]], the velvet belly is [[bioluminescence|bioluminescent]], with light-emitting [[photophore]]s forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in [[countershading|counter-illumination]], which [[crypsis|camouflages]] the shark against [[predator]]s and prey.<ref>{{Cite journal|last1=Straube|first1=N.|last2=Chenhong|first2=L.|last3=Claes|first3=J.M.|last4=Corrigan|first4=S.|last5=Naylor|first5=G.J.P.|year=2015|title=Molecular phylogeny of squaliforms and first occurrence of bioluminescence in sharks|journal=Evolutionary Biology|volume=15|page=162|doi=10.1186/s12862-015-0446-6|pmid=26277575|pmc=4537554 |doi-access=free }}</ref><ref>{{Cite journal|last1=Claes|first1=J.M.|last2=Aksnes|first2=D.L.|last3=Mallefet|first3=J.|year=2010|title=Phantom hunter of the fjords: Camouflage by counterillumination in a shark (Etmopterus spinax)|journal=Journal of Experimental Marine Biology and Ecology|volume=388|issue=1–2|pages=28–32|doi=10.1016/j.jembe.2010.03.009}}</ref> The bioluminescent flank markings may play a role in intraspecific communication.<ref>{{Cite journal|last1=Straube|first1=N.|last2=Iglésias|first2=S.P.|last3=Sellos|first3=D.Y.|last4=Kriwet|first4=J.|last5=Schliewen|first5=U.K.|year=2010|title=Molecular phylogeny and node time estimation of bioluminescent lantern sharks (Elasmobranchii: Etmopteridae)|journal=Molecular Phylogenetics and Evolution|volume=56|issue=3|pages=905–917|doi=10.1016/j.ympev.2010.04.042|pmid=20457263}}</ref>

Young velvet bellies feed mainly on [[krill]] and small [[bony fish]], transitioning to [[squid]] and [[shrimp]] as they grow larger. There is evidence that individuals also move into deeper water as they age. This species exhibits a number of [[adaptation]]s to living in the deep sea, such as specialized [[T-cell]]s and [[liver]] [[protein]]s for dealing with the higher concentrations of [[heavy metal (chemistry)|heavy metal]]s found there. Velvet bellies often carry a heavy [[parasite load]]. It is [[ovoviviparous]], giving birth to litters of six to 20 young every two to three years. This species has virtually no commercial value, but large numbers are caught as [[bycatch]] in deepwater [[commercial fishing|commercial fisheries]]. It has been assessed as Near Threatened by the [[International Union for Conservation of Nature]], the heavy fishing pressure throughout its range and its slow reproductive rate are raising conservation concerns.

==Taxonomy== [[File:Etmopterus spinax Gervais.jpg|thumb|left|Profile view of a velvet belly lanternshark, from ''Les Poissons'' (1877).]] The velvet belly was originally described as ''Squalus spinax'' by Swedish natural historian [[Carl Linnaeus]], known as the "father of [[Taxonomy (biology)|taxonomy]]", in the 1758 [[10th edition of Systema Naturae|tenth edition]] of ''[[Systema Naturae]]''. He did not designate a [[type specimen]]; the [[specific name (zoology)|specific epithet]] ''spinax'' is in reference to the spiny [[dorsal fin]]s. This species was later moved to the genus ''Etmopterus'' via the [[synonym (biology)|synonymy]] of [[Constantine Samuel Rafinesque]]'s ''Etmopterus aculeatus'' with ''Squalus spinax''.<ref name="compagno">{{cite book |author=Compagno, L.J.V. |year=1984 |title=Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date |place=Rome |publisher=Food and Agricultural Organization |isbn=92-5-101384-5 |page=85}}</ref>

The velvet belly is grouped with the [[Caribbean lanternshark]] (''E. hillianus''), [[fringefin lanternshark]] (''E. schultzi''), [[brown lanternshark]] (''E. unicolor''), [[broadbanded lanternshark]] (''E. gracilispinis''), [[combtooth lanternshark]] (''E. decacuspidatus''), and [[dwarf lanternshark]] (''E. perryi'') in having irregularly arranged, needle-shaped [[dermal denticle]]s.<ref name="springer and burgess">{{cite journal |title=Two New Dwarf Dogsharks (''Etmopterus'', Squalidae), Found off the Caribbean Coast of Colombia |author1=Springer, S. |author2=G.H. Burgess |name-list-style=amp |journal=Copeia |volume=1985 |issue=3 |date=August 5, 1985 |pages=584–591 |doi=10.2307/1444748 |publisher=American Society of Ichthyologists and Herpetologists |jstor=1444748}}</ref> Its [[common name]] comes from this shark's black ventral surface, which is sharply delineated from the rest of its body like a patch of [[velvet]].<ref name="ellis">{{cite book |author=Ellis, R. |title=Deep Atlantic: Life, Death, and Exploration in the Abyss |publisher=The Lyons Press |year=1996 |isbn=1-55821-663-4 |pages=195–196}}</ref>

==Distribution and habitat== The range of the velvet belly is in the eastern Atlantic, extending from Iceland and Norway to Gabon, including the [[Mediterranean Sea]], the [[Azores]], the [[Canary Islands]], and [[Cape Verde]]. It has also been reported off [[Cape Province]], South Africa. This shark mainly inhabits the outer [[Continental shelf|continental]] and insular shelves and upper slopes over mud or clay, from close to the bottom to the middle of the water column.<ref name="compagno"/><ref name="sion et al">{{cite journal |author=Sion, L. |author2=Bozzano, A. |author3=D'Onghia, G. |author4=Capezzuto, F. |author5=Panza, M. |name-list-style=amp |title=Chondrichthyes species in deep waters of the Mediterranean Sea |journal=Scientia Marina |volume=68 |issue=S3 |year=2004 |pages=153–162 |doi=10.3989/scimar.2004.68s3153|doi-access=free }}</ref> It is most common at a depth of {{convert|200|-|500|m|ft|abbr=on}}, though in the [[Rockall Trough]], it is only found at a depth of {{convert|500|-|750|m|ft|abbr=on}}.<ref name="martin"/><ref name="mauchline and gordon">{{cite journal |author1=Mauchline, J. |author2=Gordon, J.D.M. |name-list-style=amp |title=Diets of the sharks and chimaeroids of the Rockall Trough, northeastern Atlantic Ocean |journal=Marine Biology |volume=75 |issue=2–3 |pages=269–278 |year=1983 |doi=10.1007/BF00406012|s2cid=84676692 }}</ref> This species has been reported from as shallow as {{convert|20|m|ft|abbr=on}},<ref name=":0" /> and as deep as {{convert|2490|m|ft|abbr=on}}.<ref name="jones et al"/>

==Description== [[File:Etmopterus spinax 005.jpg|thumb|left|upright=1.2|The black underside of the velvet belly lanternshark gives it its common name.]] The velvet belly is a robustly built shark with a moderately long, broad, flattened snout. The mouth has thin, smooth lips. The upper teeth are small, with a narrow central [[Cusp (dentistry)|cusp]] and usually fewer than three pairs of lateral cusplets. The lower teeth are much larger, with a strongly slanted, blade-like cusp at the top and interlocking bases. The five pairs of [[gill slit]]s are tiny, comparable in size to the [[Spiracle (vertebrates)|spiracle]]s. Both dorsal fins bear stout, grooved spines at the front, with the second much longer than the first and curved. The first dorsal fin originates behind the short and rounded [[pectoral fin]]s; the second dorsal fin is twice the size of the first and originates behind the [[pelvic fin]]s. The [[anal fin]] is absent. The tail is slender, leading to a long [[caudal fin]] with a small lower lobe and a low upper lobe with a prominent ventral notch near the tip.<ref name="compagno"/>

The [[dermal denticle]]s are thin with hooked tips, arranged without a regular pattern well-separated from one another. The coloration is brown above, abruptly transitioning to black below. There are thin black marks above and behind the pelvic fins, and along the caudal fin.<ref name="compagno"/> The velvet belly possesses numerous photophores that emit a blue-green light visible from {{convert|3|-|4|m|ft|abbr=on}} away.<ref name="ellis"/> Varying densities of photophores are arranged in nine patches on the shark's sides and belly, creating a pattern unique to this species: photophores are present along the [[lateral line]], scattered beneath the head but excluding the mouth, evenly on the belly, and concentrated around the pectoral fins and beneath the [[caudal peduncle]].<ref name="martin">Martin, R.A. [http://www.elasmo-research.org/education/ecology/deepsea-velvetbelly.htm Deep Sea: Velvetbelly Lanternshark]. ReefQuest Centre for Shark Research. Retrieved on June 24, 2009.</ref><ref name="claes and mallefet">{{cite journal |author1=Claes, J.M. |author2=Mallefet, J. |name-list-style=amp |title=Early development of bioluminescence suggests camouflage by counter-illumination in the velvet belly lantern shark ''Etmopterus spinax'' (Squaloidea: Etmopteridae) |journal=Journal of Fish Biology |volume=73 |issue=6 |pages=1337–1350 |year=2008 |doi=10.1111/j.1095-8649.2008.02006.x}}</ref> The maximum reported length is {{convert|60|cm|in|abbr=on}}, although few are longer than 45 cm (18 in).<ref name="martin"/> Females are larger than males.<ref name="hickling"/>

==Biology and ecology== [[File:Etmopterus spinax formalin.jpg|thumbnail|Velvet belly lanternshark preserved in formalin.]] Along with the [[blackmouth catshark]] (''Galeus melastomus'') and the [[Portuguese dogfish]] (''Centroscymnus coelolepis''), the velvet belly is one of the most abundant deep-sea sharks in the northeastern Atlantic.<ref name="carrasson et al">{{cite journal |author=Carrassón, M. |author2=Stefanescu, C. |author3=Cartes, J.E. |name-list-style=amp |title=Diets and bathymetric distributions of two bathyal sharks of the Catalan deep sea (western Mediterranean) |journal=Marine Ecology Progress Series |volume=82 |issue=1 |pages=21–30 |year=1992 |doi=10.3354/meps082021|bibcode=1992MEPS...82...21C |doi-access=free |hdl=10261/183828 |hdl-access=free }}</ref> It is found individually or in small [[shoaling and schooling|shoals]].<ref name="klimpel">{{cite journal |author=Klimpel, S. |author2=Palm, H.W. |author3=Seehagen, A. |name-list-style=amp |title=Metazoan parasites and food composition of juvenile ''Etmopterus spinax'' (L., 1758) (Dalatiidae, Squaliformes) from the Norwegian Deep |journal=Parasitology Research |year=2003 |volume=89 |pages=245–251 |pmid=12632160 |issue=4 |doi=10.1007/s00436-002-0741-1|s2cid=20906694 }}</ref> Samplings in the Mediterranean have found females outnumbering males across all ages; this imbalance increases in the older age classes.<ref name="gennari and scacco">{{cite journal |author1=Gennari, E. |author2=Scacco, U. |name-list-style=amp |title=First age and growth estimates in the deep water shark, ''Etmopterus Spinax'' (Linnaeus, 1758), by deep coned vertebral analysis |journal=Marine Biology |volume=152 |issue=5 |pages=1207–1214 |doi=10.1007/s00227-007-0769-y |year=2007|s2cid=52087579 }}</ref> In the [[Rockall Trough]] and the [[Catalan Sea]], large adults are found in deeper waters than juveniles, which may serve to reduce competition between the two groups.<ref name="carrasson et al"/> However, this pattern has not been observed at other sites in the eastern Mediterranean.<ref name="jones et al">{{cite journal |author=Jones, E.G. |author2=Tselepides, E. |author3=Bagley, P.M. |author4=Collins, M.A. |author5=Priede, I.G. |name-list-style=amp |title=Bathymetric distribution of some benthic and benthopelagic species attracted to baited cameras and traps in the deep eastern Mediterranean |journal=Marine Ecology Progress Series |volume=251 |pages=75–86 |year=2003 |doi=10.3354/meps251075|bibcode=2003MEPS..251...75J |doi-access=free }}</ref>

The velvet belly's liver accounts for 17% of its body mass, three-quarters of which is [[oil]], making it nearly [[neutral buoyancy|neutrally buoyant]].<ref>{{cite journal |author=Schmidt-Nielsen, S. |author2=Flood, A. |author3=Stene, J. |name-list-style=amp |year=1934 |title=On the size of the liver of some gristly fishes, their content of fat and vitamin A |journal=Kongeleige Norske Videnskabers Selskab Forhandlinger |volume=7 |pages=47–50}}</ref> To deal with the higher concentrations of heavy metals in the deep sea, the velvet belly has [[T-cell]]s in its [[bloodstream]] that can identify and mark toxic compounds for elimination. These T-cells are produced by a [[lymphatic system|lymphomyeloid]] [[gland]] in its [[esophagus]] called a "[[Leydig's organ]]", which is also found in some other sharks and rays. In its liver, specialized proteins are also capable of detoxifying [[cadmium]], [[copper]], [[mercury (element)|mercury]], [[zinc]], and other toxic contaminants.<ref name="martin"/> The velvet belly's bioluminescence is thought to function in counter-illumination, which eliminates the shark's silhouette and camouflages it from upward-looking predators.<ref name="claes and mallefet"/> Its bioluminescence may also serve a social function, such as finding mates or co-ordinating groups, as the pattern is species-specific. The velvet belly is an important food of larger fishes such as other sharks; a major predator of this species is the [[Dipturus oxyrinchus|longnosed skate]] (''Dipturus oxyrinchus'').<ref name="martin"/><ref name="klimpel"/>

[[File:Etmopterus spinax 010.jpg|thumb|Velvet bellies are often heavily parasitized; this shark has an ''Anelasma squalicola'' barnacle attached near the fin spine.]] Numerous [[parasite]]s are known for this species, and both juveniles and adults often carry heavy parasite loads. Known internal parasites include the [[monogenea]]n ''Squalonchocotyle spinacis'', the [[tapeworm]]s ''Aporhynchus norvegicus'', ''Lacistorhynchus tenuis'', and ''Phyllobothrium squali'', and the [[nematode]]s ''Anisakis simplex'' and ''Hysterothylacium aduncum''. Some of these parasites use the velvet belly's prey as intermediate hosts and are acquired via ingestion, while others use the shark itself as an intermediate host.<ref name="klimpel" /> The [[barnacle]] ''[[Anelasma squalicola]]'', an external parasite, attaches to the shark's dorsal spine socket and penetrates deeply into the muscle, in the process often providing an attachment site for a second (and rarely a third) barnacle. Infestation by this barnacle reduces its host's [[fecundity]] by impairing the development of the [[reproductive organ]]s.<ref name="hickling">{{cite journal |title=On the small deep-sea shark Etmopterus spinax L., and its cirripede parasite Anelasma squalicola (Lovén) |author=Hickling, C.F. |journal=Journal of the Linnean Society of London, Zoology |volume=45 |issue=303 |pages=17–24 |doi=10.1111/j.1096-3642.1963.tb00484.x |year=1963}}</ref>

===Feeding=== As generalist predators, velvet bellies feed on crustaceans (e.g. [[Pasiphaeidae|pasiphaeid shrimp]] and [[krill]]), cephalopods (e.g. [[Ommastrephidae|ommastrephid squid]] and [[Sepiolidae|sepiolid]]s), and bony fishes (e.g. [[Sternoptychidae|shads]], [[barracudina]]s, [[lanternfish]]es, and [[Gadidae|pouts]]).<ref name="martin"/> Sharks off [[Italy]] also eat small amounts of nematodes, [[polychaete worm]]s, and other cartilaginous fishes.<ref>{{cite book |author=Serena, F. |author2=Cecchi, E. |author3=Mancusi, C. |author4=Pajetta, R. |name-list-style=amp |chapter=Contribution to the knowledge of the biology of ''Etmopterus spinax'' (Linnaeus 1758) (Chondrichthyes, Etmopteridae) |pages=388–394 |title=Deep Sea 2003: Conference on the Governance and Management of Deep-sea Fisheries |publisher=Food and Agricultural Organization |year=2006 |isbn=92-5-105457-6 |editor=FAO}}</ref> Studies of velvet bellies off Norway and [[Portugal]], and in the Rockall Trough, have found small sharks under {{convert|27|cm|in|abbr=on}} long feed mainly on the krill ''[[Meganyctiphanes norvegica]]'' and the small fish ''[[Maurolicus muelleri]]''. As the sharks grow larger, their diets become more varied, consisting mainly of squid and the shrimp ''[[Pasiphaea tarda]]'', as well fishes other than ''M. muelleri''.<ref name="mauchline and gordon"/><ref name="klimpel"/><ref>{{cite journal |author=Neiva, J. |author2=Coelho, R. |author3=Erzini, K. |name-list-style=amp |title=Feeding habits of the velvet belly lanternshark ''Etmopterus spinax'' (Chondrichthyes: Etmopteridae) off the Algarve, southern Portugal |journal=Journal of the Marine Biological Association of the United Kingdom |year=2006 |volume=86 |issue=4 |pages=835–841 |doi=10.1017/S0025315406013762|bibcode=2006JMBUK..86..835N |s2cid=84644449 }}</ref> It has been speculated that smaller velvet bellies may be too slow to catch fast-moving cephalopods.<ref name="klimpel"/> The cephalopod diet of adults overlaps with that of the Portuguese dogfish; the latter species may avoid competition with the velvet belly by living in deeper water.<ref name="carrasson et al"/> The bite force exerted by the velvet belly is only around 1 [[Newton (unit)|N]].<ref>{{cite journal |author=Huber, D.R. |author2=Claes, J.M. |author3=Mallefet, J. |author4=Herrel, A. |name-list-style=amp |title=Is Extreme Bite Performance Associated with Extreme Morphologies in Sharks? |journal=Physiological and Biochemical Zoology |volume=82 |issue=1 |pages=20–28 |year=2009 |doi=10.1086/588177 |pmid=19006469|s2cid=2686887 }}</ref>

===Life history=== The velvet belly is [[ovoviviparous]], with the [[embryo]]s hatching inside the [[uterus]] and being sustained by a [[yolk sac]]. The reproductive cycle may be two to three years long, with [[ovulation]] occurring in early autumn, [[fertilization]] in the summer (or possibly in the winter if females are capable of storing sperm), and parturition in late winter or early spring. The [[gestation period]] is under one year.<ref name="hickling"/><ref name="coelho and erzini">{{cite journal |author1=Coelho, R. |author2=Erzini, K. |name-list-style=amp |title=Life history of a wide-ranging deepwater lantern shark in the north-east Atlantic, ''Etmopterus spinax'' (Chondrichthyes: Etmopteridae), with implications for conservation |journal=Journal of Fish Biology |volume=73 |issue=6 |pages=1419–1443 |year=2008 |doi=10.1111/j.1095-8649.2008.02021.x}}</ref> The litter size is six to 20, with the number of young increasing with female size. At birth, the young measure {{convert|12|-|14|cm|in|abbr=on}} long.<ref name="compagno"/><ref name="coelho and erzini"/> The shark's bioluminescence develops before birth; the yolk sac is [[fluorescence|fluorescent]] before any photophores have formed, suggesting the mother transfers luminescent materials to her offspring. The first luminous tissue appears when the embryo is {{convert|55|mm|in|abbr=on}} long, and the complete pattern is laid down by the time it is {{convert|95|mm|in|abbr=on}} long. At birth, the young shark is already capable of counter-illumination with 80% of its ventral surface luminescent.<ref name="claes and mallefet"/>

The growth rate of the velvet belly is slow, though faster than some other deep-sea sharks, such as the [[leafscale gulper shark]] (''Centrophorus squamosus'') or the [[shortspine spurdog]] (''Squalus mitsukurii''). Males [[sexual maturation|mature sexually]] at {{convert|28|-|33|cm|in|abbr=on}} long and females at {{convert|34|-|36|cm|in|abbr=on}} long.<ref name="martin"/><ref name="gennari and scacco"/> The average age at maturity is 4.0 years for males and 4.7 years for females, though four-year-old mature individuals of both sexes have been caught in the wild, along with immature females over eight years old.<ref name="coelho and erzini"/> Males and females eight and 11 years old, respectively, have been caught in the wild; the potential lifespan of this species has been estimated at 18 years for males and 22 years for females.<ref name="gennari and scacco"/><ref name="coelho and erzini"/>

==Human interactions== Throughout their range, substantial quantities of velvet bellies are caught as [[bycatch]] in [[bottom trawl]]s meant for [[shrimp]] and [[lobster]]s, and [[longline fishing|deepwater longline]]s meant for other fish. Lacking commercial value, these sharks are almost always discarded with extremely high mortality, though occasionally they are [[salting (food)|dried and salted]] or made into [[fishmeal]].<ref name="compagno"/><ref name="gennari and scacco"/> The [[International Union for Conservation of Nature|IUCN]] has listed the velvet belly under [[Least Concern]] overall, as its population remains stable across much of its range, and it is afforded some protection in the Mediterranean from a 2005 ban on bottom trawling below {{convert|1000|m|ft|abbr=on}}. It has been assessed as [[Near Threatened]], as its numbers have declined by almost 20% from 1970 to 1998–2004.<ref name="iucn">{{Cite iucn | author = Coelho, R. | author2 = Blasdale, T. | author3 = Mancusi, C. | author4 = Serena, F. | author5 = Guallart, J. | author6 = Ungaro, N. | author7 = Litvinov, F. | author8 = Crozier, P. | author9 = Stenberg, C. | name-list-style = amp | title = ''Etmopterus spinax'' | volume = 2009 | article-number = e.T161388A5412576 | date = 2009 | doi = 10.2305/IUCN.UK.2009-2.RLTS.T161388A5412576.en }}</ref> The slow reproductive rate of this species limits its capacity to recover from population depletion.<ref name="coelho and erzini"/>

==References== {{Reflist}}

==External links== {{Commons category|Etmopterus spinax}} *[http://www.fishbase.org/Summary/SpeciesSummary.php?ID=687 "''Etmopterus spinax'', Velvet belly lantern shark" at FishBase] *[http://www.elasmo-research.org/education/ecology/deepsea-velvetbelly.htm "Deep Sea: Velvetbelly Lanternshark" at ReefQuest Centre for Shark Research] *[http://shark-references.com/species/view/Etmopterus-spinax "Species description of ''Etmopterus spinax''" at Shark-References.com]

[[Category:Etmopterus]] [[Category:Bioluminescent sharks]] [[Category:Fish described in 1758]] [[Category:Animal taxa named by Carl Linnaeus]]