Chimaera
From Wikipedia, the free encyclopedia
| Chimaeras Fossil range: Early Devonian-Recent[1] |
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| Hydrolagus colliei | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Holocephali |
| Order: | Chimaeriformes |
| Families | |
Chimaeras are cartilaginous fish in the order Chimaeriformes, known informally as ghost sharks, ratfish (not to be confused with the rattails), or rabbitfishes (not to be confused with the "true" rabbitfishes of the family Siganidae). They may be the "oldest and most enigmatic groups of fishes alive today."[2] At one time a "diverse and abundant" group (based on the fossil record), their closest living relatives are sharks, though in evolutionary terms they branched off from sharks nearly 400 million years ago and have remained isolated ever since, typically confined to deep water.[2]
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[edit] Description and habits
Chimaeras live in temperate ocean floors down to 2,600 metres (8,500 ft) depth, with few occuring at depths shallower than 200 metres (660 ft). Exception include the members of the genus Callorhinchus, the rabbit fish and the spotted ratfish, which locally/periodically can be found at relatively shallow depths. Consequently, these are also among the only species from the Chimaera order that are kept in public aquaria.[3] They have elongated, soft bodies, with a bulky head and a single gill-opening. They grow up to 150 centimetres (4.9 ft) in length, although this includes the – in some species – lengthy tail. In many species, the snout is modified into an elongated sensory organ.[4]
Like other members of the class Chondrichthyes, chimaeras have a skeleton constructed of cartilage. Their skin is smooth and lacks scales, and their color can range from black to brownish gray. For defense, most chimaeras have a venomous spine located in front of the dorsal fin.
Chimaeras resemble sharks in some ways: they employ claspers for internal fertilization of females and they lay eggs with leathery cases. However, unlike sharks, male chimaeras also have retractable sexual appendages on the forehead (a type of tentaculum)[5] and in front of the pelvic fins.[4] The females lay eggs in spindle-shaped leathery cases.[1]
They also differ from sharks in that their upper jaws are fused with their skulls and they have separate anal and urogenital openings. They lack the many sharp and replaceable teeth of sharks, having instead just three pairs of large permanent grinding tooth plates.[4]
[edit] Classification
In some classifications the chimaeras are included (as subclass Holocephali) in the class Chondrichthyes of cartilaginous fishes; in other systems this distinction may be raised to the level of class. Chimaeras also have some characteristics of bony fishes.
A renewed effort to explore deep water and to undertake taxonomic analysis of specimens in museum collections have led to a boom during the first decade of the 21st century in the number of new species identified.[2] There are about forty extant species in six genera and three families (an additional three genera and two family are only known from fossils):
Family Callorhinchidae
- Genus Callorhinchus
- Elephant fish, Callorhinchus callorynchus (Linnaeus, 1758)
- Cape elephantfish, Callorhinchus capensis (Duméril, 1865)
- Australian ghost shark, Callorhinchus milii Bory de Saint-Vincent, 1823
- Genus †Edaphodon-prehistoric
- †Edaphodon agassizi Buckland, 1835
- †Edaphodon antwerpiensis Leriche, 1926
- †Edaphodon bucklandi Agassiz, 1843
- †Edaphodon eyrensis Long, 1985
- †Edaphodon kawai Consoli, 2006
- †Edaphodon laqueatus Leidy, 1873
- †Edaphodon leptognathus - (has not been formally classified) Agassiz
- †Edaphodon minor
- †Edaphodon mirabilis - (has not been formally classified)
- †Edaphodon mirificus Leidy, 1856
- †Edaphodon sedgwicki
- †Edaphodon smocki Cope
- †Edaphodon stenobryus Cope
- †Edaphodon tripartitus Cope
Family Chimaeridae
- Genus Chimaera
- Chimaera argiloba
- Chimaera cubana Howell Rivero, 1936
- Chimaera fulva Southern Chimaera
- Chimaera jordani Jordan's ChimaeraTanaka, 1905
- Carpenter's chimaera, Chimaera lignaria Didier, 2002
- Chimaera macrospina Longspine Chimaera
- Chimaera monstrosa Rabbit fish Linnaeus, 1758
- Chimaera obscura Shortspine Chimaera
- Chimaera owstoni Owston's Chimaera Tanaka, 1905
- Chimaera panthera Leopard Chimaera Didier, 1998
- Chimaera pseudomonstrosa
- Silver chimaera, Chimaera phantasma Jordan & Snyder, 1900
- Chimaera sp. G Cape Chimaera
- Genus Hydrolagus
- Smalleyed rabbitfish, Hydrolagus affinis (de Brito Capello, 1868)
- African chimaera, Hydrolagus africanus (Gilchrist, 1922)
- Hydrolagus alberti Bigelow & Schroeder, 1951
- Hydrolagus alphus Quaranta et al., 2006.[6]
- Hydrolagus barbouri (Garman, 1908)
- Pale ghost shark, Hydrolagus bemisi Didier, 2002
- Spotted ratfish, Hydrolagus colliei (Lay & Bennett, 1839)
- Philippine chimaera, Hydrolagus deani (Smith & Radcliffe, 1912)
- Hydrolagus eidolon (Jordan & Hubbs, 1925)
- Hydrolagus homonycteris Black Ghost Shark
- Blackfin ghostshark, Hydrolagus lemures (Whitley, 1939)
- Hydrolagus macrophthalmus de Buen, 1959
- Hydrolagus marmoratus Marbled Ghost Shark
- Hydrolagus matallanasi Sotto & Vooren, 2004
- Hydrolagus mccoskeri
- Hydrolagus melanophasma
- Hydrolagus media (Garman, 1911).
- Large-eyed rabbitfish, Hydrolagus mirabilis (Collett, 1904)
- Spookfish, Hydrolagus mitsukurii (Jordan & Snyder, 1904).
- Dark ghost shark, Hydrolagus novaezealandiae (Fowler, 1911)
- Hydrolagus ogilbyi (Waite, 1898)
- Hydrolagus pallidus Hardy & Stehmann, 1990
- Purple chimaera, Hydrolagus purpurescens (Gilbert, 1905)
- Pointy-nosed blue chimaera, Hydrolagus trolli Didier & Séret, 2002
- Hydrolagus waitei Fowler, 1908
- Hydrolagus sp. D/G Giant Black Chimaera
- Hydrolagus sp. F Peruvian Ratfish
Family Rhinochimaeridae
- Genus Harriotta
- Smallspine spookfish, Harriotta haeckeli Karrer, 1972
- Narrownose chimaera, Harriotta raleighana Goode & Bean, 1895.
Narrownose chimaera, Harriotta raleighana
- Genus Neoharriotta
- Neoharriotta carri Bullis & Carpenter, 1966
- Sicklefin chimaera, Neoharriotta pinnata (Schnakenbeck, 1931)
- Neoharriotta pumila Didier & Stehmann, 1996
- Genus Rhinochimaera
- Rhinochimaera africana Compagno, Stehmann & Ebert, 1990
- Spearnose chimaera, Rhinochimaera atlantica Holt & Byrne, 1909
- Pacific spookfish, Rhinochimaera pacifica (Mitsukuri, 1895)
Family †Squalorajidae
- Genus Squaloraja Agassiz, 1836
Family †Echinochimaeridae
- Genus Echinochimaera Lund, 1977
- †Echinochimaera meltoni Lund, 1977
- †Echinochimaera snyderi Lund, 1988
[edit] See also
[edit] References
Specific references:
- ^ a b "Chimaeriformes". FishBase. Ed. Ranier Froese and Daniel Pauly. January 2009 version. N.p.: FishBase, 2009.
- ^ a b c "Ancient And Bizarre Fish Discovered: New Species Of Ghostshark From California And Baja California". ScienceDaily. September 23, 2009. http://www.sciencedaily.com/releases/2009/09/090922095816.htm. Retrieved 2009-09-23.
- ^ Tozer, H., & D. D. Dagit (2004). Husbandry of Spotted Ratfish, Hydrolagus colliei.
- ^ a b c Stevens, J. & Last, P.R. (1998). Paxton, J.R. & Eschmeyer, W.N.. ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 69. ISBN 0-12-547665-5.
- ^ Freaky New Ghostshark ID’d Off California Coast, a September 22, 2009 blog post from Wired Science
- ^ Quaranta et al. (2006). "A new species of chimaeroid, Hydrolagus alphus sp. nov. (Chimaeriformes: Chimaeridae) from the Galapagos Islands". Zootaxa 1377: 33–45. http://www.mapress.com/zootaxa/2006f/z01377p045f.pdf.
General references:
- "Chimaeriformes". FishBase. Ed. Ranier Froese and Daniel Pauly. January 2006 version. N.p.: FishBase, 2006.
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