bio.wikisort.org - AnimalThe sawback angelshark (Squatina aculeata) is an angelshark of the family Squatinidae[2] It is one of rarest species of sharks known to date, and one of the three species of angelsharks that inhabits the Mediterranean. The Sawback angelshark lives in sandy and muddy bottoms of the ocean at depths of 30-500m.[3]
Species of shark
Sawback angelshark |
 |
Conservation status |
 Critically Endangered (IUCN 3.1)[1] |
Scientific classification  |
Kingdom: |
Animalia |
Phylum: |
Chordata |
Class: |
Chondrichthyes |
Superorder: |
Selachimorpha |
Order: |
Squatiniformes |
Family: |
Squatinidae |
Genus: |
Squatina |
Species: |
S. aculeata |
Binomial name |
Squatina aculeata
|
 |
Range of sawback angelshark (in gold) |
Measurements
Their size at birth ranges from 30-35cm. As adults, female measurements range from 137-143cm, while males range from 120-122cm.[4] Their relative weight based on the size of the shark for males is between 12.7kg and 24.0kg. In females, they weigh anywhere from 22-32kg.[5] The females grow to be larger than the males because they need to be able to carry and support their young.
Development
The development of the males was measured in three stages, juvenile, subadult and adult. The juvenile males had short and flexible claspers and the testes were membranous and barely developed. The subadult males showed changes in the claspers involving slight calcification and elongation in the sharks. It is in the adult stage that the claspers are fully elongated and calcified, and are rigid. The spermatozoa had developed and sperm production became possible in these adult sharks.
The three development stages for females are the same for males: juvenile, subadult and adult. The juvenile females have whitish ovaries, and extremely small ovaries, which need to be seen under a microscope. In the subadult females, they have primarily white, translucent follicles, differentiated genital areas, and developed ovarian glands. In adult females, the fully functional ovaries exhibits developing and fully developed follicles.[5]
Appearance
Their eyes are larger than their spiracle. The frontal cephalic membranes are lobed; external nasal flap fringed; spiracle with 13-14 pseudo branchial lamellae. Has concave between eye, eye spiracle distance <1.5 x eye length. They have between 19 and 24 teeth, the average of the species being 21 total teeth. Their pectoral fin base at is least half of their fin length. They have denticles on their back which are large-based, almost pyramidal, with a line of median spines. The lower belly of the shark has denticles only on outer edges of pectoral and pelvic fins Obtains large thorns atop its head in a row down its back. The colour of the angelshark is light brown mottled with dark brown, with white sports arranged on the head and some of the body. Obtains dark blotches on head, back, the fin bases and tail. The species contains no ocelli.[6]
Distribution and range
The range of the Sawback Angelshark continues to decrease as their population declines. They range along the Eastern Atlantic in Senegal, Gambia, and Sierra Leone. They also inhabit the Southern Mediterranean coastline in Algeria to the eastern basin, and along the northern coast from Turkey possibly to Albania, although their presence is unknown further east. Its presence is unknown in Algeria, Sardinia, Malta, Libya, Egypt, Palestine, Lebanon, Syria, southern Cyprus, Crete, ad Western Mainland Greece.[7]
Climate and habitat
Subtropical; offshore species, outer continental shelf and upper slope, demersal, marine. Usually found on muddy bottoms. 30–500 m (98–1,640 ft) down.
Behavior
As with other angelsharks, the sawback angelshark is a bottom-dweller that tries to camouflage at the bottom of the ocean in order to ambush and capture its prey.
Feeding
Angelsharks are ambush predators, meaning they lie on the ocean floor and wait for their prey to pass by. They feed on small sharks, bony fishes, cephalopods, and crustaceans.[8]
Reproduction
Angelsharks reproduction is ovoviviparous. This means the young develop inside the mother as eggs until they are ready to hatch. The average generation of the Sawback Angelshark is 15 years, so they have a low population doubling time. Females produce live young, and their litter size ranges from 8 to 12 pups.[8] The female fecundity ranges from 12 to 22, and larger females sharks tend to have a higher fecundity and produce more offspring than smaller females.
Status
IUCN Red List: Critically Endangered. Added to endangered species list in 2007 due to overexploitation.[7] One major source of their decline has been contamination in the North-Eastern Mediterranean. Due to agricultural, industrial and urban wastes, the Mediterranean has seen an untick in the amount of toxic heavy metals. The metals most present are Iron (Fe), Zinc (Zn), and Mercury (Hg). These metals have been found in dangerous quantities in Angelsharks gills, liver and muscle tissues.
Another major contributing factor to the decline of the species has been fisheries and overfishing in the Mediterranean. This comes from Illegal, unreported and unregulated (IUU) fishing, commercial fishing (lack of species identification, as well as the impact of different gear types), recreational fishing, subsidence/food security and small scale fishing. Human intrusion into the angel sharks environment has also caused a significant disruption to their habitat and breeding spaces. Lastly, residential and commercial development has added to the decline of the species including coastal building and infrastructure development, renewable energy sources like underwater turbines. Combined, these have led to the decline in population numbers causing a lack of genetic diversity in the species.[9]
Threat to Humans
The Sawback Angelshark is a harmless species, but may be dangerous to humans if provoked or their habitat is disturbed.
References
- Morey, G.; Barker, J.; Bartolí, A.; Gordon, C.; Hood, A.; Jimenez-Alvarado, D.; Meyers, E.K.M. (2019). "Squatina aculeata". IUCN Red List of Threatened Species. 2019: e.T61417A116768915. doi:10.2305/IUCN.UK.2019-1.RLTS.T61417A116768915.en. Retrieved 18 November 2021.
- "Species Squatina aculeata Cuvier". FishWisePro. 1829. Retrieved 19 April 2020.
- Başusta, Nuri (2016-06-01). "New records of neonate and juvenile sharks (Heptranchias perlo, Squatina aculeata, Etmopterus spinax) from the North-eastern Mediterranean Sea". Marine Biodiversity. 46 (2): 525–527. doi:10.1007/s12526-015-0391-z. ISSN 1867-1624.
- Lawson, Julia M; Pollom, Riley A; Gordon, Cat A; Barker, Joanna; Meyers, Eva K M; Zidowitz, Heike; Ellis, Jim R; Bartolí, Álex; Morey, Gabriel; Fowler, Sarah L; Alvarado, David Jiménez; Fordham, Sonja V; Sharp, Rowland; Hood, Ali R; Dulvy, Nicholas K (2019-12-13). "Extinction risk and conservation of critically endangered angel sharks in the Eastern Atlantic and Mediterranean Sea". ICES Journal of Marine Science. 77 (1): 12–29. doi:10.1093/icesjms/fsz222. ISSN 1054-3139.
- Christian Capapé, Y. Diatta, A.A. Seck, Olivier Guélorget (June 2005). "Reproduction of the sawback angelshark Squatina aculeata (Chondrichthyes: Squatinidae) off Senegal and Tunisia". Research Gate. Retrieved 11 November 2022.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - Irmak, Erhan. "Occurence [sic] of Squatina aculeata Cuvier, 1829 (Elasmobranchii, Squatinidae) from the Aegean Sea, Turkey".
- Morey, G.; Barker, J.; Bartolí, A.; Gordon, C.; Hood, A.; Jimenez-Alvarado, D.; Meyers, E.K.M. (2019). "Squatina aculeata". IUCN Red List of Threatened Species. 2019: e.T61417A116768915. doi:10.2305/IUCN.UK.2019-1.RLTS.T61417A116768915.en. Retrieved 18 November 2021.
- Fisheries, NOAA (2022-01-26). "Sawback Angelshark | NOAA Fisheries". NOAA. Retrieved 2022-10-26.
- Pepin-Neff, Christopher; Wynter, Thomas (2017-09-13). "Shark Bites and Shark Conservation: An Analysis of Human Attitudes Following Shark Bite Incidents in Two Locations in Australia". Conservation Letters. 11 (2): e12407. doi:10.1111/conl.12407. ISSN 1755-263X.
Research Sources
- Froese, Rainer; Pauly, Daniel (eds.) (2006). "Squatina aculeata" in FishBase. July 2006 version.
- Compagno, Dando, & Fowler, Sharks of the World, Princeton University Press, New Jersey 2005 ISBN 0-691-12072-2
- Turan, Cemal, et al. Occurrence of a Sawback Angelshark (Squatina Aculeata Cuvier, 1829 ... Faculty of Marine Sciences and Technology, Iskenderun Technical University, 22 Aug. 2019, http://biozoojournals.ro/bihbiol/cont/v14n1/bb_e192303_Ergenler.pdf.
External links
Sharks portal
Extant shark species |
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- Kingdom Animalia
- Phylum Chordata
- Subphylum Vertebrata
- Class Chondrichthyes
- Subclass Elasmobranchii
- Subdivision Selachii
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Order Carcharhiniformes (Ground sharks) |
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Hemigaleidae (Weasel sharks) | Hemipristis | |
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Chaenogaleus |
- Hooktooth shark (C. macrostoma)
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Hemigaleus | |
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Paragaleus | |
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Leptochariidae | Leptocharias |
- Barbeled houndshark (L. smithii)
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Proscylliidae (Finback sharks) | Ctenacis | |
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Eridacnis | |
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Proscyllium |
- Graceful catshark (P. habereri)
- P. venustum
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Pseudotriakidae | Gollum |
- Slender smooth-hound (G. attenuatus)
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Pseudotriakis |
- False catshark (P. microdon)
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|
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Sphyrnidae (Hammerhead sharks) | Eusphyra |
- Winghead shark (E. blochii)
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Sphyrna | |
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Triakidae (Houndsharks) | Furgaleus |
- Whiskery shark (F. macki)
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Galeorhinus | |
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Gogolia | |
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Hemitriakis | |
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Hypogaleus | |
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Iago | |
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Mustelus (Smooth-hounds) | |
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Scylliogaleus |
- Flapnose houndshark (S. quecketti)
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Triakis | |
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Carcharhinidae |
- Large family listed below
|
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Scyliorhinidae |
- Large family listed below
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Family Carcharhinidae (Requiem sharks) |
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Carcharhinus | |
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Galeocerdo | |
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Glyphis (River sharks) | |
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Isogomphodon | |
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Lamiopsis |
- Broadfin shark (L. temminckii)
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Loxodon | |
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Nasolamia | |
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Negaprion | |
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Prionace | |
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Rhizoprionodon | |
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Scoliodon |
- Spadenose shark (S. laticaudus)
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Triaenodon |
- Whitetip reef shark (T. obesus)
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|
|
Family Scyliorhinidae (Catsharks) |
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Apristurus | |
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Asymbolus |
- Australian spotted catshark (A. analis)
- A. funebris
- Western spotted catshark (A. occiduus)
- Pale spotted catshark (A. pallidus)
- A. parvus
- A. rubiginosus
- Variegated catshark (A. submaculatus)
- Gulf catshark (A. vincenti)
|
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Atelomycterus |
- A. baliensis
- Banded sand catshark (A. fasciatus)
- Australian marbled catshark (A. macleayi)
- Coral catshark (A. marmoratus)
|
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Aulohalaelurus | |
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Cephaloscyllium |
- Whitefin swellshark (C. albipinnum)
- Circle-blotch pygmy swellshark (C. circulopullum)
- Cook's swellshark (C. cooki)
- Reticulated swellshark (C. fasciatum)
- Formosa swellshark (C. formosanum)
- Australian reticulate swellshark (C. hicosellum)
- Draughtsboard shark (C. isabellum)
- Australian swellshark (C. laticeps)
- Spotted swellshark (C. maculatum)
- Leopard-spotted swellshark (C. pardelotum)
- Painted swellshark (C. pictum)
- Sarawak pygmy swellshark (C. sarawakensis)
- Flagtail swellshark (C. signourum)
- Indian swellshark (C. silasi)
- Speckled swellshark (C. speccum)
- Balloon shark (C. sufflans)
- Blotchy swellshark (C. umbratile)
- Saddled swellshark (C. variegatum)
- Swellshark (C. ventriosum)
- Narrowbar swellshark (C. zebrum)
|
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Cephalurus | |
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Figaro |
- Australian sawtail catshark (F. boardmani)
- Northern sawtail catshark (F. striatus)
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Galeus | |
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Halaelurus | |
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Haploblepharus |
- Puffadder shyshark (H. edwardsii)
- Brown shyshark (H. fuscus)
- Natal shyshark (H. kistnasamyi)
- Dark shyshark (H. pictus)
|
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Holohalaelurus |
- H. favus
- H. grennian
- Crying izak (H. melanostigma)
- African spotted catshark (H. punctatus)
- Izak catshark (H. regani)
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Parmaturus | |
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Pentanchus | |
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Poroderma |
- Pyjama catshark (P. africanum)
- Leopard catshark (P. pantherinum)
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Schroederichthys | |
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Scyliorhinus | |
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Order Echinorhiniformes (Bramble sharks) |
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|
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Order Heterodontiformes (Bullhead sharks) |
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Order Hexanchiformes |
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Chlamydoselachidae | Chlamydoselachus |
- Frilled shark (C. anguineus)
- Southern African frilled shark (C. africana)
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|
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Hexanchidae (Cow sharks) | Heptranchias |
- Sharpnose sevengill shark (H. perlo)
|
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Hexanchus |
- Bluntnose sixgill shark (H. griseus)
- Bigeyed sixgill shark (H. nakamurai)
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Notorynchus | |
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Order Lamniformes (Mackerel sharks) |
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Alopiidae | Alopias (Thresher sharks) | |
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Cetorhinidae | Cetorhinus |
- Basking shark (C. maximus)
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Lamnidae | Carcharodon |
- Great white shark (C. carcharias)
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Isurus | |
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Lamna | |
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Megachasmidae | Megachasma |
- Megamouth shark (M. pelagios)
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Mitsukurinidae | |
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Odontaspididae | Carcharias |
- Grey nurse shark (C. taurus)
- Indian sand tiger (C. tricuspidatus)
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Odontaspis | |
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Pseudocarchariidae | Pseudocarcharias |
- Crocodile shark (P. kamoharai)
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Order Orectolobiformes (Carpet sharks) |
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Brachaeluridae | Brachaelurus | |
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Heteroscyllium |
- Bluegrey carpetshark (H. colcloughi)
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Ginglymostomatidae (Nurse sharks) | |
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Hemiscylliidae (Bamboo sharks) | Chiloscyllium | |
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Hemiscyllium | |
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Orectolobidae (Wobbegongs) | Eucrossorhinus |
- Tasselled wobbegong (E. dasypogon)
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Orectolobus | |
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Sutorectus |
- Cobbler wobbegong (S. tentaculatus)
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Parascylliidae (Collared carpet sharks) | Cirrhoscyllium | |
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Parascyllium |
- Collared carpetshark (P. collare)
- Rusty carpetshark (P. ferrugineum)
- Ginger carpetshark (P. sparsimaculatum)
- Necklace carpetshark (P. variolatum)
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Rhincodontidae | |
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Stegostomatidae | |
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Order Pristiophoriformes (Sawsharks) |
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Pristiophoridae | Pliotrema |
- Sixgill sawshark (P. warreni)
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Pristiophorus | |
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Order Squaliformes |
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Centrophoridae (Gulper sharks) | |
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Dalatiidae | Euprotomicroides |
- Taillight shark (E. zantedeschia)
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Heteroscymnoides |
- Longnose pygmy shark (H. marleyi)
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Mollisquama | |
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Dalatias | |
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Isistius |
- Cookiecutter shark (I. brasiliensis)
- South China cookiecutter shark (I. labialis)
- Largetooth cookiecutter shark (I. plutodus)
|
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Euprotomicrus |
- Pygmy shark (E. bispinatus)
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Squaliolus |
- Smalleye pygmy shark (S. aliae)
- Spined pygmy shark (S. laticaudus)
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|
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Etmopteridae | Aculeola |
- Hooktooth dogfish (A. nigra)
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Centroscyllium |
- Highfin dogfish (C. excelsum)
- Black dogfish (C. fabricii)
- Granular dogfish (C. granulatum)
- Bareskin dogfish (C. kamoharai)
- Combtooth dogfish (C. nigrum)
- Ornate dogfish (C. ornatum)
- Whitefin dogfish (C. ritteri)
|
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Etmopterus (Lantern sharks) |
- New Zealand lanternshark (E. baxteri)
- Blurred lanternshark (E. bigelowi)
- Shorttail lanternshark (E. brachyurus)
- Lined lanternshark (E. bullisi)
- E. burgessi
- Cylindrical lanternshark (E. carteri)
- Tailspot lanternshark (E. caudistigmus)
- Combtooth lanternshark (E. decacuspidatus)
- Pink lanternshark (E. dianthus)
- E. dislineatus
- Blackmouth lanternshark (E. evansi)
- Pygmy lanternshark (E. fusus)
- Broadbanded lanternshark (E. gracilispinis)
- Southern lanternshark (E. granulosus)
- Caribbean lanternshark (E. hillianus)
- Smalleye lantern shark (E. litvinovi)
- Blackbelly lanternshark (E. lucifer)
- Slendertail lanternshark (E. molleri)
- Dwarf lanternshark (E. perryi)
- African lanternshark (E. polli)
- Great lanternshark (E. princeps)
- False lanternshark (E. pseudosqualiolus)
- Smooth lanternshark (E. pusillus)
- Dense-scale lantern shark (E. pycnolepis)
- West Indian lanternshark (E. robinsi)
- Fringefin lanternshark (E. schultzi)
- Thorny lanternshark (E. sentosus)
- Velvet belly lantern shark (E. spinax)
- Splendid lanternshark (E. splendidus)
- Tasmanian lanternshark (E. tasmaniensis)
- Brown lanternshark (E. unicolor)
- Hawaiian lanternshark (E. villosus)
- Green lanternshark (E. virens)
|
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Miroscyllium |
- Rasptooth dogfish (M. sheikoi)
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Trigonognathus | |
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Oxynotidae (Rough sharks) | |
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Somniosidae (Sleeper sharks) | Centroscymnus | |
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Centroselachus | |
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Proscymnodon |
- Largespine velvet dogfish (P. macracanthus)
- Plunket shark (P. plunketi)
|
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Scymnodalatias |
- Whitetail dogfish (S. albicauda)
- Azores dogfish (S. garricki)
- Sparsetooth dogfish (S. oligodon)
- Sherwood dogfish (S. sherwoodi)
|
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Scymnodon |
- Smallmouth velvet dogfish (S. obscurus)
- Knifetooth dogfish (S. ringens)
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Somniosus | |
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Zameus | |
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Squalidae (Dogfish sharks) | Cirrhigaleus |
- Roughskin spurdog (C. asper)
- Mandarin dogfish (C. barbifer)
|
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Squalus (Spurdogs) |
- Spiny dogfish (S. acanthias)
- Eastern highfin spurdog (S. albifrons)
- S. acutirostris
- Western highfin spurdog (S. altipinnis)
- Longnose spurdog (S. blainville)
- Fatspine spurdog (S. crassispinus)
- Cuban dogfish (S. cubensis)
- Eastern longnose spurdog (S. grahami)
- Japanese spurdog (S. japonicus)
- Shortnose spurdog (S. megalops)
- Blacktailed spurdog (S. melanurus)
- Shortspine spurdog (S. mitsukurii)
- Bartail spurdog (S. notocaudatus)
- Western longnose spurdog (S. nasutus)
- Cyrano spurdog (S. rancureli)
- Pacific spiny dogfish (S. suckleyi)
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Order Squatiniformes (Angel sharks) |
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На других языках
- [en] Sawback angelshark
[ru] Squatina aculeata
Обыкновенный морской ангел[2] (лат. Squatina aculeata) — вид рода плоскотелых акул одноимённого семейства отряда скватинообразных. Эти акулы встречаются в западной части Атлантического океана на глубине до 500. Максимальная зарегистрированная длина 188 см. У них плоские голова и тело. Они размножаются путём яйцеживорождения. Рацион состоит из небольших рыб и беспозвоночных. Представляют незначительный интерес для коммерческого рыбного промысла[3].
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