Editing Bullhead shark

{{Short description|Genus of sharks}}
{{Redirect|Heterodontus|the snake|Heterodon}}
{{Automatic taxobox
| fossil_range = {{fossilrange|Late Jurassic|Present}}
| image = Hornhai (Heterodontus francisci).JPG
| image_caption = [[Horn shark]], ''Heterodontus francisci''
| display_parents = 5
| grandparent_authority = 
| parent_authority = [[John Edward Gray|J. E. Gray]], 1851
| taxon = Heterodontus
| authority = [[Henri Marie Ducrotay de Blainville|Blainville]], 1816
| type_species = ''[[Heterodontus portusjacksoni|Squalus portusjacksoni]]''
| type_species_authority = [[F. A. A. Meyer]], 1793
| subdivision_ranks = Species
| subdivision = See [[#Species|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 {{convert|1.65|m|ft|round=0.5}} in maximum length. They are bottom feeders in tropical and subtropical waters.

The Heterodontiforms appear in the fossil record in the [[Early Jurassic]]. 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 the [[Cretaceous–Paleogene extinction event|Cretaceous-Paleogene extinction]], with diversification into modern species only starting around the mid-[[Eocene]].<ref name=":1">{{Cite journal |last1=Slater |first1=Tiffany S. |last2=Ashbrook |first2=Kate |last3=Kriwet |first3=Jürgen |date=2020 |editor-last=Cavin |editor-first=Lionel |title=Evolutionary relationships among bullhead sharks (Chondrichthyes, Heterodontiformes) |url=https://onlinelibrary.wiley.com/doi/10.1002/spp2.1299 |journal=Papers in Palaeontology |language=en |volume=6 |issue=3 |pages=425–437 |doi=10.1002/spp2.1299 |bibcode=2020PPal....6..425S |issn=2056-2799|hdl=10468/10339 |hdl-access=free }}</ref>

==Description==
Bullhead sharks have tapered bodies, with most species reaching around {{Convert|70-130|cm|ft}} in length. Their bodies vary in colour, including shades of grey, brown, and red and pale colours, and are covered in a variety of patterns, including spots and stripes.<ref name=":2">{{Cite book |last=Carvalho |first=Marcelo |url= |title=Grzimek's Animal Life Encyclopedia |date=2002 |chapter=Heterodontiformes (Bullhead or Horn Sharks) |chapter-url=https://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/heterodontiformes-bullhead-or-horn-sharks |via=Encyclopedia.com}}</ref> They have blunt, proportionally large heads with relatively small mouths and large nostrils, with pronounced ridges above their eyes. They have two dorsal fins, both substantial in size, the first larger than the second, each of which has a rigid fin spine at the front, along with an anal fin.<ref>{{Cite journal |last1=White |first1=William T. |last2=Mollen |first2=Frederik H. |last3=O’Neill |first3=Helen L. |last4=Yang |first4=Lei |last5=Naylor |first5=Gavin J. P. |date=2023-07-12 |title=Species in Disguise: A New Species of Hornshark from Northern Australia (Heterodontiformes: Heterodontidae) |journal=Diversity |language=en |volume=15 |issue=7 |pages=849 |doi=10.3390/d15070849 |doi-access=free |issn=1424-2818}}</ref><ref name=":2" /> The tail fin is also large, with upper and lower lobes separated by a notch.<ref name=":2" /> Bullhead sharks have differentiated teeth, with cusped grasping teeth at the front of the mouth, and flattened teeth at the back of the mouth.<ref name=":1" /> Their [[Egg case (Chondrichthyes)|egg cases]] have a spiral colarettes running along their length.<ref>{{Cite journal |last1=Fischer |first1=Jan |last2=Licht |first2=Martin |last3=Kriwet |first3=Jürgen |last4=Schneider |first4=Jörg W. |last5=Buchwitz |first5=Michael |last6=Bartsch |first6=Peter |date=2014-04-03 |title=Egg capsule morphology provides new information about the interrelationships of chondrichthyan fishes |url=http://www.tandfonline.com/doi/abs/10.1080/14772019.2012.762061 |journal=Journal of Systematic Palaeontology |language=en |volume=12 |issue=3 |pages=389–399 |doi=10.1080/14772019.2012.762061 |bibcode=2014JSPal..12..389F |issn=1477-2019}}</ref>

== Ecology ==
Bullhead sharks live in coastal [[Littoral zone|littoral]] environments,<ref name=":1" /> generally shallower than {{Convert|100|m|ft}}, and are usually primarily active at night.<ref name=":2" /> Bullhead sharks ingest prey via [[suction feeding]].<ref>{{Cite journal |last1=Edmonds |first1=Margaret A. |last2=Motta |first2=Philip J. |last3=Hueter |first3=Robert E. |date=December 2001 |title=Food capture kinematics of the suction feeding horn shark, Heterodontus francisci |url=http://link.springer.com/10.1023/A:1012205518704 |journal=Environmental Biology of Fishes |language=en |volume=62 |issue=4 |pages=415–427 |doi=10.1023/A:1012205518704 |bibcode=2001EnvBF..62..415E |issn=0378-1909}}</ref> They feed on invertebrate prey, including both hard prey such as [[Crustacean|crustaceans]] and [[Sea urchin|sea urchins]], and soft bodied prey such as [[Octopus|octopuses]], as well as predating on fish.<ref>{{Cite journal |last1=Cortés-Fuentes |first1=Christian |last2=Simental-Anguiano |first2=María del Rosario |last3=Galván-Magaña |first3=Felipe |last4=Medina-López |first4=Marco Antonio |date=April 2020 |title=Feeding habits of the horn shark Heterodontus francisci (Girard, 1855) in the northwest of Baja California Sur, Mexico |url=https://onlinelibrary.wiley.com/doi/10.1111/jai.14004 |journal=Journal of Applied Ichthyology |language=en |volume=36 |issue=2 |pages=197–202 |doi=10.1111/jai.14004 |bibcode=2020JApIc..36..197C |issn=0175-8659|doi-access=free }}</ref> They use their flattened teeth at the back of the mouth to [[Durophagy|crush hard-shelled prey]] and fish.<ref name=":1" /> Juveniles generally take softer prey than adults.<ref name=":2" /> The sharp fin spines provide a deterrent to being consumed by predators.<ref name=":2" />

Bullhead shark [[Egg case (Chondrichthyes)|egg cases]] are shaped like an [[Auger (drill)|auger]], with two spiral flanges. This allows the egg cases to become wedged in the crevices of rocky sea floors, where the eggs are protected from predators; however, some bullhead sharks deposit their eggs on sponges or seaweed.<ref>{{Cite web |last=Buch |first=Robert |title=Heterodontus francisci |url=https://www.floridamuseum.ufl.edu/fish/discover/species-profiles/heterodontus-francisci/ |website=Florida Museum}}</ref><ref name=":22">{{Cite journal |last=Compagno |first=Leonard |date=2002 |title=Sharks of the World |journal=FAO Species Catalogue for Fishery Purposes |volume=2 |pages=31–50}}</ref> Hatchlings are considered large for sharks, reaching over 14&nbsp;cm in length by the time they leave the egg case.<ref name=":22" /> Bullhead shark eggs typically hatch after 7 to 12 months, depending on the species.<ref name=":22" /> The female [[Japanese bullhead shark]] has been known to deposit their eggs in one location along with other females, called a "nest".<ref name=":22" /> The egg case of the [[Mexican hornshark]] features a tendril and more rigid flanges, suggesting that egg case design of this species primarily involves anchoring with tendrils rather than wedging into crevices.<ref name=":22" />[[File:Oeufs002b,55.png|thumb|upright=0.5|Bullhead shark [[Egg case (Chondrichthyes)|egg case]]]]

==Species==
Ten living species of bullhead shark have been described:
* ''[[Horn shark|Heterodontus francisci]]'' <small>([[Charles Frédéric Girard|Girard]], 1855)</small> (horn shark)
* ''[[Crested bullhead shark|Heterodontus galeatus]]'' <small>([[Albert Günther|Günther]], 1870)</small> (crested bullhead shark)
* ''[[Japanese bullhead shark|Heterodontus japonicus]]'' <small>([[Nicholas Miklouho-Maclay|Maclay]] & [[William John Macleay|W. J. Macleay]], 1884)</small> (Japanese bullhead shark)
* ''[[Painted hornshark|Heterodontus marshallae]]'' <small>White, Mollen, O'Neill, Yang & Naylor, 2023</small> (painted hornshark)
* ''[[Mexican hornshark|Heterodontus mexicanus]]'' <small>([[Leighton R. Taylor Jr.|L. R. Taylor]] & [[José Luis Castro-Aguirre|Castro-Aguirre]], 1972)</small> (Mexican hornshark)
* ''[[Oman bullhead shark|Heterodontus omanensis]]'' <small>([[Zachary Hayward Baldwin|Z. H. Baldwin]], 2005)</small> (Oman bullhead shark)
* ''[[Port Jackson shark|Heterodontus portusjacksoni]]'' <small>([[Friedrich Albrecht Anton Meyer|F. A. A. Meyer]], 1793)</small> (Port Jackson shark)
* ''[[Galapagos bullhead shark|Heterodontus quoyi]]'' <small>([[Christophe Paulin de la Poix de Fréminville|Fréminville]], 1840)</small> (Galapagos bullhead shark)
* ''[[Whitespotted bullhead shark|Heterodontus ramalheira]]'' <small>([[James Smith (ichthyologist)|J. L. B. Smith]], 1949)</small> (whitespotted bullhead shark)
* ''[[Zebra bullhead shark|Heterodontus zebra]]'' <small>([[John Edward Gray|J. E. Gray]], 1831)</small> (zebra bullhead shark)

<gallery widths=180>
File:Heterodontus philippi.jpg|A [[Port Jackson shark]], ''Heterodontus portusjacksoni''
File:Heterodontus portusjacksoni 1.jpg|[[Dentition]] and [[wikt:oronasal|oronasal]] grooves of a Port Jackson shark
File:Heterodontus zebra.jpg|[[Zebra bullhead shark]], ''Heterodontus zebra''
</gallery>

==See also==
{{Portal|Sharks}}
* [[List of prehistoric cartilaginous fish]]

==References==
{{Reflist}}

==Further reading==
* Compagno, Leonard (2002) [http://www.fao.org/docrep/009/x9293e/x9293e00.htm ''Sharks of the World: Bullhead, mackerel and carpet sharks''] Volume 2, FAO Species Catalogue, Rome. {{ISBN|92-5-104543-7}}.

{{Shark nav}}
{{Chondrichthyes}}
{{Selachimorpha|He.}}
{{Taxonbar|from=Q44511}}
{{Authority control}}

[[Category:Heterodontidae]]
[[Category:Toarcian first appearances]]
[[Category:Extant Early Jurassic first appearances]]
[[Category:Taxa named by Henri Marie Ducrotay de Blainville]]