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The '''Squaliformes''' are an [[order (biology)|order]] of [[shark]]s that includes about 126 species in seven families.
The '''Squaliformes''' are an [[order (biology)|order]] of [[shark]]s that includes about 126 species in seven families.


Members of the order have two [[dorsal fin]]s, which usually possess spines,they ussualy have a sharp head, no [[anal fin]] or [[nictitating membrane]], and five [[gill slit]]s. In most other respects, however, they are quite variable in form and size. Most species of the squaliform order live in a saltwater or brackish waters, They are found worldwide, from polar to tropical waters, and from shallow coastal seas to the open ocean.<ref name=EoF>{{cite book |editor=Paxton, J.R. |editor2=Eschmeyer, W.N.|author1=Stevens, J. |author2=Last, P.R. |lastauthoramp=yes |year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|page= 64|isbn= 0-12-547665-5}}</ref>
Members of the order have two [[dorsal fin]]s, which usually possess spines,they ussualy have a sharp head, no [[anal fin]] or [[nictitating membrane]], and five [[gill slit]]s. In most other respects, however, they are quite variable in form and size. Most species of the squaliform order live in a saltwater or brackish waters, They are found worldwide, from polar to tropical waters, and from shallow coastal seas to the open ocean.<ref name=EoF>{{cite book |editor=Paxton, J.R. |editor2=Eschmeyer, W.N.|author1=Stevens, J. |author2=Last, P.R. |lastauthoramp=yes |year=1998|title=Encyclopedia of Fishes|publisher= Academic Press|location=San Diego|page= 64|isbn= 0-12-547665-5}}</ref>


==Classification==
==Classification==

Revision as of 19:03, 5 November 2018

Squaliformes
Temporal range: Late Jurassic–Recent[1]
Spiny dogfish, Squalus acanthias
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Division: Selachii
Superorder: Squalomorphi
Order: Squaliformes
Goodrich, 1909

The Squaliformes are an order of sharks that includes about 126 species in seven families.

Members of the order have two dorsal fins, which usually possess spines,they ussualy have a sharp head, no anal fin or nictitating membrane, and five gill slits. In most other respects, however, they are quite variable in form and size. Most species of the squaliform order live in a saltwater or brackish waters, They are found worldwide, from polar to tropical waters, and from shallow coastal seas to the open ocean.[2]

Classification

Family Centrophoridae Bleeker, 1859 (gulper sharks)

Family Dalatiidae (J. E. Gray, 1851) (kitefin sharks)

Family Echinorhinidae Theodore Gill, 1862 (bramble sharks)

Family Etmopteridae Fowler, 1934 (lantern sharks)

Family Oxynotidae Gill, 1872 (rough sharks)

Family Somniosidae D. S. Jordan, 1888 (sleeper sharks)

Family Squalidae Blainville, 1816 (dogfish sharks)

Family Image Common name Genera Species Description
Centrophoridae Gulper sharks 2 20 Gulper sharks are usually deepwater fish. While some, such as the gulper shark Centrophorus granulosus, are found worldwide and fished commercially, others are uncommon and little-known. Their usual prey is other fish; some are known to feed on squid, octopus, and shrimp. Some species live on the bottom (benthic), while others are pelagic. They are ovoviviparous, with the female retaining the egg-cases in her body until they hatch.[3] They are small to medium sharks, ranging from 79 centimetres (2.59 ft) to 164 centimetres (5.38 ft) in adult body length.
Dalatiidae Kitefin sharks 7 10 Kitefin sharks are small, under 2 m (6.6 ft) long, and are found worldwide. They have cigar-shaped bodies with narrow heads and rounded snouts. Several species have specialized bioluminescent organs.[4] The term kitefin shark is also used as the common name for the type species of the family, Dalatias licha.
Echinorhinidae Bramble sharks 1 2 Bramble sharks are usually benthic fish found in tropical and temperate waters worldwide, while the prickly shark is found in the deep waters of the Pacific Ocean. Their usual prey is small fish, cephalopods, and crustaceans. They are ovoviviparous, with the female retaining the egg cases in her body until they hatch.[5] They are relatively large sharks, ranging from 3.1 to 4 metres (10 to 13 ft) in adult body length.}}
Etmopteridae Lantern sharks 5 45 Lantern sharks are deepwater fish with light-producing photophores on their bodies. The members of this family are small, under 90 cm (35 in) long, and are found worldwide.[6]
Oxynotidae Rough sharks 1 5 Rough sharks are characterised by two large dorsal fins, each with a sharp spine, and with the first fin placed far forward above the head. Their bodies are compressed, giving them a triangular cross-section. Their skins are even rougher and more prickly than the dogfishes (below). Rough sharks are small to medium in size, ranging from 49 to 150 centimetres (1.61 to 4.92 ft) in adult body length, depending on species. They are deepwater sharks possessing a luminous organ which live in Atlantic and western Pacific oceans.[7]
Somniosidae Sleeper sharks 7 20 Sleeper sharks are a poorly studied[8] deep-sea shark found in all oceans.[9] They contain antifreeze to survive in cold temperatures, and may feed on colossal squid. In Iceland, they are hunted for food. They are allowed to rot for months until the poisonous antifreeze degrades, and they are safe to eat.[10]
Squalidae Dogfish sharks 2 30 Dogfish sharks have two dorsal fins, each with smooth spines, but no anal fin. Their skin is generally rough to the touch.[11] These sharks are characterized by teeth in upper and lower jaws similar in size; caudal peduncle with lateral keels; upper precaudal pit usually present; and a caudal fin without a subterminal notch. Unlike nearly all other shark species, dogfish possess venom, which coats their dorsal spines and is mildly toxic to humans. Their livers and stomachs contain also the compound squalamine, which possesses the property of reduction of small blood vessel growth in humans.[12]

References

  1. ^ Froese, Rainer; Pauly, Daniel (eds.). "Order Squaliformes". FishBase. January 2009 version.
  2. ^ Stevens, J.; Last, P.R. (1998). Paxton, J.R.; Eschmeyer, W.N. (eds.). Encyclopedia of Fishes. San Diego: Academic Press. p. 64. ISBN 0-12-547665-5. {{cite book}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)
  3. ^ Froese, Rainer; Pauly, Daniel (eds.). "Family Centrophoridae". FishBase. January 2009 version.
  4. ^ Hamlett, W.C., ed. (1999). Sharks, Skates, and Rays: The Biology of Elasmobranch Fishes. JHU Press. pp. 16–17. ISBN 0-8018-6048-2.
  5. ^ {{FishBase_family| family=Echinorhinidae
  6. ^ Froese, Rainer; Pauly, Daniel (eds.). "Family Etmopteridae". FishBase. February 2011 version.
  7. ^ Froese, Rainer; Pauly, Daniel (eds.). "Family Oxynotidae". FishBase. January 2009 version.
  8. ^ "Abstract". Springer Links. Retrieved 29 December 2012.
  9. ^ "Family Somniosidae - Sleeper sharks". Fish Base. Retrieved 29 December 2012.
  10. ^ Simon, Matt. "Footnotes: Lazy Sharks, Humiliated Seals, and Googlers Eating Dog Food | Wired Opinion". Wired.com. Retrieved 2012-07-05.
  11. ^ Froese, Rainer; Pauly, Daniel (eds.). "Family Squalidae". FishBase. January 2009 version.
  12. ^ National Geographic June 1998

Further reading

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