Draughtsboard shark
| Draughtsboard shark | |
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Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Order: | Carcharhiniformes |
| Family: | Scyliorhinidae |
| Genus: | Cephaloscyllium |
| Species: | C. isabellum
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| Binomial name | |
| Cephaloscyllium isabellum (Bonnaterre,1788)
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| Range of the draughtsboard shark | |
| Synonyms | |
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Thedraughtsboard shark(Cephaloscyllium isabellum) is aspeciesofcatshark,and part of thefamilyScyliorhinidae,so named for its "checkerboard"colour pattern of dark blotches. It isendemictoNew Zealand,where it is also known as thecarpet shark(which usually refers to the entireorderOrectolobiformes).[2]This shark typically reaches 1 m (3.3 ft) in length and has a thick body with a broad, flattened head and a capacious mouth. Its twodorsal finsare placed far back on the body, with the first much larger than the second.
Occurring down to a depth of 673 m (2,208 ft), the draughtsboard shark frequents rockyreefsduring the day and sandy flats at night. Its diet consists of fishes andinvertebrates.When threatened by apredator,it can take water or air into its body to inflate its body, which may be the cause of its unusual habit ofbarkinglike adog.This species isoviparous,with females laying smooth, tendril-bearingegg capsulesin pairs. Draughtsboard sharks are often taken asbycatchbycommercial fisheries,but are probably hardy enough to survive the experience. TheInternational Union for Conservation of Nature(IUCN) has listed this species underLeast Concern.
Taxonomy
[edit]FrenchnaturalistPierre Joseph Bonnaterreoriginally described the draughtsboard shark asSqualus isabella,in the 1788ichthyologyvolume of theTableau encyclopédique et méthodique des trois règnes de la nature.He based his account on "L'Isabelle", referred to by Pierre-Marie-Auguste Broussonet in a 1780Histoire de l'Académie Royale des Sciencespaper. Thetype specimenhas since been lost. Later authors moved this species to the genusCephaloscyllium.[3]
The draughtsboard shark closely resembles theblotchy swellshark(C. umbratile) and theAustralian swellshark(C. laticeps), both of which have been suspected to be the same species asC. isabellumby different authors at various times. The draughtsboard shark differs from the Australian swellshark in colouration and the form of itsegg capsules(smooth inC. isabellumand ridged inC. laticeps).[4]It differs from the blotchy swellshark in colouration andmorphometric measurements.[5]
Distribution and habitat
[edit]The draughtsboard shark is found only in the coastal waters around New Zealand, includingthe Snares,theChatham Islands,andStewart Island,where it is particularly common. It typically occurs at depths of 0 to 400 m (0 to 1,312 ft) oncontinental and insular shelves,though it has been recorded from as far down as 673 m (2,208 ft). This shark is abottom-dwellerthat favors rockyreefsand adjacent areas of soft substrate. Adult males and females segregate from each other.[1][6]
Description
[edit]Most draughtsboard sharks measure no more than 1 m (3.3 ft) long, though rarely an individual may reach 1.5 m (4.9 ft); a recorded maximum size of 2.4 m (7.9 ft) was probably based on thebroadnose sevengill shark(Notorynchus cepedianus) or some other species. Females grow larger than males.[1][4]This shark has a stocky, spindle-shaped body that tapers to a relatively thincaudal peduncle.The head is short, broad, and somewhat flattened, with a broadly rounded snout. Thenostrilshave a triangular flap of skin in front, that do not reach the mouth. The oval eyes have rudimentarynictitating eyelidsand are placed somewhat on top of the head; they have thick ridges above and below, and are followed byspiracles.The mouth is very large and curved, without furrows at the corners and with the upper teeth exposed when closed.[4]
Thepectoral finsare fairly large and broad. The twodorsal finsare placed far back on the body, with the first originating about over the middle of thepelvic finbases and the second originating over theanal fin.The second dorsal fin is much smaller than the first, and also smaller than the anal fin. Males have short and thickclaspers.Thecaudal finis short and broad, with a barely developed lower lobe and a strong ventral notch near the tip of the upper lobe. The skin is thick and covered by well-calcifieddermal denticles.The colouration of the draughtsboard shark gives it itscommon name:it is golden to brown above and light below, with up to 11 dark brown, irregular dorsal "saddles" that alternate with blotches on its flanks to form acheckerboardpattern.[4][6]Also distinctive is the saddle between its spiracles, which is stretched out and swept back on each side to form a bar over the gill slits.[7]
Biology and ecology
[edit]During the day, the draughtsboard shark is lethargic and typically hides inside crevices or caves on the reef.[4][6]At night, it emerges to forage for food over nearby sandy flats. This shark consumes a wide variety of fishes and invertebrates, includingspiny dogfish,cod,sand perch,blennies,octopus,squid,gastropods,innkeeper worms,krill,hermit crabs,crabs,spiny lobsters,and evensea squirts.Individuals have been observed sucking innkeeper worms out of their burrows, and swimming around with theantennaeof large lobsters sticking out of their mouths for hours.[6]A knownparasiteof this species is thetapewormCalyptrobothrium chalarosomum.[8]
Like otherCephaloscylliumspecies, the draughtsboard shark has the ability to inflate its body dramatically in response to apredator;this defence mechanism may be behind reports of this speciesbarkinglike a largedog.[9]While it usually inflates with water, when captured by humans and brought to the surface it may inflate with air instead. When the shark deflates, the "bark" is produced by the pressurized air as it is released explosively through thecardiac sphincterof the stomach.[9]This species isoviparous,with females laying two eggs at a time. The smooth, cream-colored egg cases measure 12 cm (4.7 in) long, and have long, spiral tendrils at the corners that allow them to be fastened to underwater objects.[1][9]Newly hatched sharks measure 16 cm (6.3 in) long; males and femalesmature sexuallyat 60 cm (24 in) and 80 cm (31 in) long respectively.[5]
Human interactions
[edit]
Common and harmless, draughtsboard sharks are oftencaught incidentallybytrawl,rock lobster,and probablyset netfisheries.It is likely that most captured sharks survive to be returned to the water alive, as this species can tolerate being out of water for an extended period of time. From 1988 to 1991, there was a New Zealandshark liverfishery and reported catches of draughtsboard sharks were 74–540 tons per year. After the fishery was discontinued, catches dropped to under five tons per year.
Conservation status
[edit]The New ZealandDepartment of Conservationhas classified the draughtsboard shark as "Not Threatened" under theNew Zealand Threat Classification System.[10]Because its population seems healthy and free from significant threats, theInternational Union for Conservation of Nature(IUCN) has assessed this species as ofLeast Concern.[1]
References
[edit]
- ^abcdeFinucci, B.; Kyne, P.M. (2018)."Cephaloscyllium isabellum".IUCN Red List of Threatened Species.2018:e.T41752A116736703.doi:10.2305/IUCN.UK.2018-2.RLTS.T41752A116736703.en.Retrieved19 November2021.
- ^Froese, Rainer;Pauly, Daniel (eds.)."Cephaloscyllium isabellum".FishBase.February 2010 version.
- ^Eschmeyer, W.N. and R. Fricke (eds.)Catalog of Fishes electronic version (15 January 2010)Archived24 August 2012 at theWayback Machine.Retrieved 8 February 2010.
- ^abcdeCompagno, L.J.V. (1984).Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date.Rome: Food and Agricultural Organization. pp. 298–299.ISBN92-5-101384-5.
- ^abCompagno, L.J.V., M. Dando and S. Fowler (2005). Sharks of the World. Princeton University Press. pp. 216–217.ISBN978-0-691-12072-0.
- ^abcdMichael, S.W. (1993).Reef Sharks & Rays of the World.Sea Challengers. p. 52.ISBN0-930118-18-9.
- ^Last, P.R., H. Motomura, and W. T. White (2008). "Cephaloscyllium albipinnumsp. nov., a new swellshark (Carcharhiniformes: Scyliorhinidae) from southeastern Australia "in Last, P.R., W.T. White and J.J. Pogonoski (eds).Descriptions of new Australian Chondrichthyans.CSIRO Marine and Atmospheric Research Paper No. 022: 147–157.ISBN0-1921424-1-0(corrected)ISBN1-921424-18-2(invalid, listed in publication).
- ^Tazerouti, F., L. Euzet and N. Kechemir-Issad (July 2007). "Redescription of three species ofCalyptrobothriummonticelli, 1893 (Tetraphyllidea: Phyllobothriidae) parasites ofTorpedo marmorataandT. nobiliana(Elasmobranchii: Torpedinidae). Remarks on their parasitic specificity and on the taxonomical position of the species previously attributed toC-riggiiMonticelli, 1893 ".Systematic Parasitology67(3): 175–185.
- ^abcMartin, R.A.Do Sharks Make Any Sounds? (archived from Archive.org).ReefQuest Centre for Shark Research. Retrieved 15 October 2012.
- ^Duffy, Clinton A. J.; Francis, Malcolm; Dunn, M. R.; Finucci, Brit; Ford, Richard; Hitchmough, Rod; Rolfe, Jeremy (2018).Conservation status of New Zealand chondrichthyans (chimaeras, sharks and rays), 2016(PDF).Wellington, New Zealand: Department of Conservation. p. 9.ISBN9781988514628.OCLC1042901090.