Squaliformes

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Squaliformes
Temporal range: Late Jurassic–Recent[1]
Pacific spiny dogfish, Squalus suckleyi
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Clade:
Neoselachii
Subdivision: Selachimorpha
Superorder: Squalomorphii
Order: Squaliformes
Goodrich, 1909
Type species
Squalus acanthias

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

Members of the order have two

open ocean.[2]

All members of the family Etmoperidae and Dalatiidae and Zameus squamulosus possess photophores, luminous organs, and exhibit intrinsic bioluminescence.[3] Bioluminescence evolved once in Squaliformes, approximately 111–153 million years ago, and helped the Squaliformes radiate and adapt to the deep sea.[3][4] The common ancestor of Dalatiidae, Etmopteridae, Somniosidae, and Oxynotidae possessed a luminous organ and used bioluminescence for camouflage by counterillumination.[3][5] Counterillumination is an active form of camouflage in which an organism emits light to match the intensity of downwelling light to hide from predators below.[6] Currently, bioluminescence provides different functions for Squaliformes based on the family. Dalatiidae and Zameus squamulosus possess simple photophores and use bioluminescence for ventral counter-illumination.[5] Etmopteridae possess more complex photophores [7] and utilize bioluminescence for ventral counter illumination as well as species recognition.[8]

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
ovoviviparous, with the female retaining the egg-cases in her body until they hatch.[9]
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
Dalatias licha
.
Echinorhinidae
Bramble sharks
 1 2 Bramble sharks are usually
ovoviviparous, with the female retaining the egg cases in her body until they hatch.[11]
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.[12]
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
Atlantic and western Pacific oceans.[13]
Somniosidae
Sleeper sharks
 7 20 Sleeper sharks are a poorly studied[14] deep-sea shark found in all oceans.[15] 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.[16]
Squalidae
Dogfish sharks
 3 31 Dogfish sharks have two dorsal fins, each with smooth spines, but no anal fin. Their skin is generally rough to the touch.
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.[18]

References

  1. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Squaliformes" in FishBase. January 2009 version.
  2. ISBN 978-0-12-547665-2
    .
  3. ^ a b c Flammesbeck, C. K.; Pollerspöck, J.; Schedel, F. D. B.; Matzke, N. J.; Straube, N. (2018). "Of teeth and trees: a fossil tip dating approach to infer divergence times of extinct and extant squaliform sharks". 2dh Annual Conference of the European Elasmobranch Association: 57.
  4. PMID 27276229
    .
  5. ^
    PMID 26277575
    .
  6. S2CID 5680392
    .
  7. ^ Claes, J. M.; Mallefet, J. (2009). "Bioluminescence of sharks: first synthesis". Kerala: Research Signpost: 51–65.
  8. PMID 26587280
    .
  9. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Centrophoridae" in FishBase. January 2009 version.
  10. ISBN 978-0-8018-6048-5
    .
  11. ^ Froese, Rainer, and Daniel Pauly, eds. (2006). "Echinorhinidae" in FishBase. April 2006 version.
  12. ^ Froese, Rainer, and Daniel Pauly, eds. (2011). "Etmopteridae" in FishBase. February 2011 version.
  13. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Oxynotidae" in FishBase. January 2009 version.
  14. S2CID 44189738
    .
  15. ^ "Family Somniosidae - Sleeper sharks". Fish Base. Retrieved 29 December 2012.
  16. ^ Simon, Matt (2012-07-05). "Footnotes: Lazy Sharks, Humiliated Seals, and Googlers Eating Dog Food | Wired Opinion". Wired. Retrieved 2012-07-05.
  17. ^ Froese, Rainer, and Daniel Pauly, eds. (2009). "Squalidae" in FishBase. January 2009 version.
  18. ^ "From the Belly of a Shark, a Cancer Cure?". National Geographic. Vol. 193, no. 6. June 1998. p. 202. Retrieved 2 January 2023.

Further reading

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