| Hexanchiformes Temporal range: Middle Jurassic–Recent [1] | |
|---|---|
| File:Frilled shark.png | |
| Frilled shark, Chlamydoselachus anguineus | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Superorder: | Selachimorpha |
| Order: | Hexanchiformes de Buen, 1926 |
| Families | |
Hexanchiformes is the order consisting of the most primitive types of sharks, and numbering just six extant species. Fossil sharks that were apparently very similar to modern sevengill species are known from Jurassic specimens.[2]
Hexanchiform sharks have only one dorsal fin, either six or seven gill slits, and no nictitating membrane in the eyes.
The frilled shark, Chlamydoselachus anguineus, is very different from the cow sharks, and it has been proposed that it be moved to its own order Chlamydoselachiformes.
Classification[]
| Family | Image | Common name | Genera | Species | Description |
|---|---|---|---|---|---|
| Chlamydoselachidae | File:Chlamydoselachus anguineus 3.jpg | Frilled sharks | 1 extant 2 extinct |
2 extant 8 extinct |
Frilled sharks contain only two extant species of deep sea creatures who are typically weakened in areas closer to the surface. The most widely known species still surviving is the frilled shark, known as a living fossil, along with the Southern African frilled shark, found along coastal areas of South Africa. There are several extinct species. |
| Hexanchidae | File:Hexanchus nakamurai.JPG | Cow sharks | 3 extant 7 extinct |
4 extant 31 extinct |
Cow sharks are considered the most primitive of all the sharks, because their skeletons resemble those of ancient extinct forms, with few modern adaptations. Their excretory and digestive systems are also unspecialised, suggesting that they may resemble those of primitive shark ancestors. Their most distinctive feature, however, is the presence of a sixth, and, in two genera, a seventh, gill slit, in addition to the five found in all other sharks.[3] They range from 1.4 metres (4.6 ft) to over 5.5 metres (18 ft) in adult body length. |
| †Mcmurdodontidae | †Mcmurdodontidae | 1 | 2 | Extinct. |
Extant species[]
- Family Chlamydoselachidae Garman 1884 (frilled sharks)
- Chlamydoselachus Garman, 1884
- Chlamydoselachus africana Ebert & Compagno, 2009 (Southern African frilled shark)
- Chlamydoselachus anguineus Garman, 1884 (Frilled shark)
- Chlamydoselachus Garman, 1884
- Family Hexanchidae J. E. Gray 1851 (cow sharks)
- Heptranchias Rafinesque, 1810
- Heptranchias perlo (Bonnaterre, 1788) (Sharpnose sevengill shark)
- Hexanchus Rafinesque, 1810
- Hexanchus griseus (Bonnaterre, 1788) (Bluntnose sixgill shark)
- Hexanchus nakamurai Teng, 1962 (Bigeyed sixgill shark)
- Notorynchus Ayres, 1855
- Notorynchus cepedianus (Péron, 1807) (Broadnose sevengill shark)
- Heptranchias Rafinesque, 1810
Extinct species[]
Notidanodon sp. fossil at the Geological Museum, Copenhagen
- Family Chlamydoselachidae
- Chlamydoselachus Garman, 1884
- Chlamydoselachus bracheri Pfeil, 1983
- Chlamydoselachus gracilis Antunes & Cappetta, 2001
- Chlamydoselachus goliath Antunes & Cappetta, 2001
- Chlamydoselachus fiedleri Pfeil, 1983
- Chlamydoselachus lawleyi Davis, 1887
- Chlamydoselachus thomsoni Richter & Ward, 1990
- Chlamydoselachus tobleri Leriche, 1929
- Thrinax Pfeil, 1983
- Thrinax baumgartneri Pfeil, 1983
- Chlamydoselachus Garman, 1884
- Family Hexanchidae
- Heptranchias Rafinesque, 1810
- Heptranchias ezoensis Applegate & Uyeno, 1968
- Heptranchias howelii (Reed, 1946)
- Heptranchias tenuidens (Leriche, 1938)
- Hexanchus Rafinesque, 1810
- Hexanchus arzoensis (Debeaumont, 1960)
- Hexanchus agassizi [1]
- Hexanchus collinsonae Ward, 1979
- Hexanchus gracilis (Davis, 1887) [2]
- Hexanchus griseus “andersoni” “gigas” (Bonaterre, 1788)
- Hexanchus hookeri Ward, 1979
- Hexanchus microdon “agassizii” (Agassiz, 1843)
- Hexanchus nakamurai “vitulus” Teng, 1962
- Notidanoides Maisey 1986 [3]
- (No named species)
- Notidanodon Cappetta, 1975
- Notidanodon antarcti Grande & Chatterjee, 1987
- Notidanodon brotzeni Siverson, 1995
- Notidanodon dentatus (Woodward, 1886)
- Notidanodon lanceolatus (Woodward, 1886)
- Notidanodon loozi (Vincent, 1876)
- Notidanodon pectinatus (Agassiz, 1843)
- Notorynchus Ayres, 1855
- Notorynchus aptiensis (Pictet, 1865)
- Notorynchus intermedius Wagner
- Notorynchus lawleyi Ciola & Fulgosi, 1983
- Notorynchus munsteri (Agassiz, 1843)
- Notorynchus serratissimus (Agassiz, 1844)
- Notorynchus serratus (Agassiz, 1844)
- Paraheptranchias PFEIL, 1981
- Paraheptranchias repens (Probst, 1879)
- Paranotidanus “Eonotidanus” contrarius (Munster, 1843)
- Paranotidanus intermedius (Wagner, 1861)
- Paranotidanus munsteri (Agassiz, 1843)
- Paranotidanus serratus (Fraas, 1855)
- Pseudonotidanus Underwood & Ward, 2004
- Pseudonotidanus semirugosus Underwood & Ward, 2004
- Weltonia Ward, 1979
- Weltonia ancistrodon (Arambourg, 1952)
- Weltonia burnhamensis Ward, 1979
- Heptranchias Rafinesque, 1810
- Family ?Mcmurdodontidae
- Mcmurdodus White, 1968
- Mcmurdodus featherensis White, 1968
- Mcmurdodus whitei Turner, & Young, 1987
- Mcmurdodus White, 1968
See also[]
- Time range of Hexanchiformes species
References[]
- ^ Template:FishBase order
- ^ Allen, 45
- ^ Matt's, J. & Last P.R. (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. p. 61. ISBN 0-12-547665-5.
- Froese, Rainer, and Daniel Pauly, eds. (2011). "Chlamydoselachidae" in FishBase. February 2011 version. (Fish Base family reference)
- Froese, Rainer, and Daniel Pauly, eds. (2011). "Hexanchidae" in FishBase. February 2011 version. (Fish Base family reference)
- Allen, Thomas B. The Shark Almanac. New York: The Lyons Press, 1999. ISBN 1-55821-582-4
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Template:Hexanchiformes
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