Biology:Bullhead shark
| Bullhead shark | |
|---|---|
.JPG)
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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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See text | |
The bullhead sharks are members of the genus Heterodontus, the only members of the family Heterodontidae and only living members of the order Heterodontiformes. 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 the Early Jurassic.[1] The oldest fossils of the modern genus date to the Late Jurassic.
Description
The bullhead sharks are characterised by a broad head, heavy brow, stubby snout and small mouth. The mouth is located entirely anterior to 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 the Port Jackson shark. The eyes lack a nictitating membrane. A spiracle is present, but small. The dorsal ends of the fourth and fifth branchial arches are attached, but not fused into a "pickaxe" as in lamniform sharks. Heterodontiforms have two dorsal fins, with fin spines, as well as an anal fin. The dorsal and anal fins also contain basal cartilages, not just fin rays.[1]
Species
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 marshallae White, 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)
A Port Jackson shark, Heterodontus portusjacksoni
Dentition and oronasal grooves of a Port Jackson shark
Zebra bullhead shark, Heterodontus zebra
See also
- List of prehistoric cartilaginous fish
References
- ↑ 1.0 1.1 Slater, Tiffany S.; Ashbrook, Kate; Kriwet, Jürgen (August 2020). Cavin, Lionel. ed. "Evolutionary relationships among bullhead sharks (Chondrichthyes, Heterodontiformes)" (in en). Papers in Palaeontology 6 (3): 425–437. doi:10.1002/spp2.1299. ISSN 2056-2799. https://onlinelibrary.wiley.com/doi/10.1002/spp2.1299.
Further reading
- Compagno, Leonard (2002) Sharks of the World: Bullhead, mackerel and carpet sharks Volume 2, FAO Species Catalogue, Rome. ISBN:92-5-104543-7.
Wikidata ☰ Q44511 entry
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