Bullhead shark
| Bullhead shark Temporal range:
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|---|---|
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| Horn shark,Heterodontus francisci | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Subclass: | Elasmobranchii |
| Clade: | Neoselachii |
| Subdivision: | Selachimorpha |
| Superorder: | Galeomorphii |
| Order: | Heterodontiformes |
| Family: | Heterodontidae J. E. Gray,1851 |
| Genus: | Heterodontus Blainville,1816 |
| Type species | |
| Squalus portusjacksoni F. A. A. Meyer,1793
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| Species | |
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Seetext | |
Thebullhead sharksare members of the genusHeterodontus,the only members of the familyHeterodontidaeand only living members of the orderHeterodontiformes.All are relatively small, with the largest species reaching just 1.65 metres (5.5 ft) in maximum length. They are bottom feeders in tropical and subtropical waters.
The Heterodontiforms appear in the fossil record in theEarly Jurassic.[1]The oldest fossils of the modern genus date to the Late Jurassic. Despite the very ancient origins of this genus and its abundance in the fossil record, phylogenetic evidence indicates that all extant species in the genus arose from a single common ancestor that survived theCretaceous-Paleogene extinction,with diversification into modern species only starting around the mid-Eocene.[2]
Description
[edit]
The bullhead sharks are characterised by a broad head, heavy brow, stubby snout and small mouth. The mouth is located entirelyanteriorto the eye sockets, due to their protruding jaw structure. They have a distinct groove from their nostrils to their mouths. They grow to about a meter in size, with the largest species being that of thePort Jackson shark.The eyes lack anictitating membrane.Aspiracleis present, but small. Thedorsalends of the fourth and fifth branchial arches are attached, but not fused into a "pickaxe" as inlamniform sharks.Heterodontiforms have twodorsal fins,with fin spines, as well as ananal fin.The dorsal and anal fins also contain basalcartilages,not just fin rays.[1]
Species
[edit]Ten living species of bullhead shark have been described:
- Heterodontus francisci(Girard,1855)(horn shark)
- Heterodontus galeatus(Günther,1870)(crested bullhead shark)
- Heterodontus japonicus(Maclay&W. J. Macleay,1884)(Japanese bullhead shark)
- Heterodontus marshallaeWhite, Mollen, O'Neill, Yang & Naylor, 2023(painted hornshark)
- Heterodontus mexicanus(L. R. Taylor&Castro-Aguirre,1972)(Mexican hornshark)
- Heterodontus omanensis(Z. H. Baldwin,2005)(Oman bullhead shark)
- Heterodontus portusjacksoni(F. A. A. Meyer,1793)(Port Jackson shark)
- Heterodontus quoyi(Fréminville,1840)(Galapagos bullhead shark)
- Heterodontus ramalheira(J. L. B. Smith,1949)(whitespotted bullhead shark)
- Heterodontus zebra(J. E. Gray,1831)(zebra bullhead shark)
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APort Jackson shark,Heterodontus portusjacksoni -
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Zebra bullhead shark,Heterodontus zebra
See also
[edit]
References
[edit]- ^abSlater, Tiffany S.; Ashbrook, Kate; Kriwet, Jürgen (August 2020). Cavin, Lionel (ed.)."Evolutionary relationships among bullhead sharks (Chondrichthyes, Heterodontiformes)".Papers in Palaeontology.6(3): 425–437.doi:10.1002/spp2.1299.hdl:10468/10339.ISSN2056-2799.
- ^Slater, Tiffany S.; Ashbrook, Kate; Kriwet, Jürgen (2020). Cavin, Lionel (ed.)."Evolutionary relationships among bullhead sharks (Chondrichthyes, Heterodontiformes)".Papers in Palaeontology.6(3): 425–437.doi:10.1002/spp2.1299.hdl:10468/10339.ISSN2056-2799.
Further reading
[edit]- Compagno, Leonard (2002)Sharks of the World: Bullhead, mackerel and carpet sharksVolume 2, FAO Species Catalogue, Rome.ISBN92-5-104543-7.
