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===Life history===
[[File:Horn shark egg morro bay.jpg|thumb|left|The spiral-flanged egg case of a horn shark<ref>{{Cite book |last=Freeborn |first=Michelle |url=https://www.wikidata.org/wiki/Q58012425 |title=The fishes of New Zealand |date=2015-01-01 |publisher=Te Papa Press |isbn=978-0-9941041-6-8 |editor-last=Roberts |editor-first=Clive Douglas |volume=2 |pages=54 |editor-last2=Stewart |editor-first2=Andrew L. |editor-last3=Struthers |editor-first3=Carl D.}}</ref>; the shape allows the egg to be secured within crevices.]]
Mating in the horn shark occurs in December or January, on a possibly annual reproductive cycle.<ref name="fowler et al"/> The male chases the female to indicate interest; once she is ready both sharks settle on the bottom, where the male grips the female's pectoral fin in his teeth and inserts one of his [[clasper]]s into her [[cloaca]]. After 30–40 minutes of [[copulation (zoology)|copulation]], the pair disengages and the female spins with her snout in the sand for another 30 minutes.<ref name="martin"/> From February to April, the females lay a maximum of 24 eggs two at a time once every 11–14 days, in water {{convert|2|-|13|m|ft|abbr=on}} deep.<ref name="iucn status 19 November 2021" /> The egg case has two flanges spiraling around it, and thus may take the female several hours to deposit.<ref name="Ref_">Martin, R.A. [http://elasmo-research.org/education/shark_profiles/heterodontiformes.htm Heterodontiformes: Bullhead Sharks]. ReefQuest Centre for Shark Research. Retrieved on June 19, 2009.</ref> At first the case is soft and light brown, and over a few days it hardens and darkens in color. Not including the flanges, the case measures {{convert|10|-|12|cm|in|abbr=on}} long and {{convert|3|-|4|cm|in|abbr=on}} wide; sharks from the Channel Islands produce longer egg cases than those from mainland California, suggesting that they are separate populations.<ref name="compagno"/><ref name="ebert"/>
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==Human interactions==
[[File:Diver and Horn Shark.jpg|thumb|Horn sharks are innocuous towards humans.]]
Under normal circumstances, horn sharks are harmless to humans and can readily be approached underwater.<ref name="ebert"/> However, they can be provoked into biting, and some pugnacious individuals have been known to chase and bite divers after being harassed.<ref name="martin"/> These sharks should be handled with care as their fin spines can inflict a painful wound.<ref name="ebert"/> The horn shark adapts well to captivity and has been maintained and bred in many [[public aquarium]]s across the United States.<ref name="compagno"/> In July 2018, three people were arrested after stealing a juvenile horn shark from the [[San Antonio]] Aquarium. The shark was smuggled out of the aquarium in a stroller under a blanket. It was returned unharmed two days later.<ref>{{Cite web|url=https://abcnews.go.com/US/shark-returned-san-antonio-aquarium-video-shows-brazen/story?id=56929004|title = Shark returned to San Antonio aquarium after being stolen in baby stroller| website=[[ABC News (United States)|ABC News]] }}</ref>
The horn shark has no commercial value in California, where it is captured unintentionally in traps and trawls and by [[recreational fishing|recreational anglers]]. The shark's hardiness ensures that it can often be returned to the water alive.<ref name="iucn status 19 November 2021" /> This species benefits from general restrictions placed on coastal fishing gear by the State of California. The average annual [[bycatch]] off California is {{convert|1800|kg|lb|abbr=on}}, though historically it has varied from {{convert|2.5|kg|lb|abbr=on}} in 1976 to {{convert|9500|kg|lb|abbr=on}} in 1979.<ref name="fowler et al">{{cite book |author=Fowler, S.L., Cavanagh, R.D., Camhi, M., Burgess, G.H., Cailliet, G.M., Fordham, S.V., Simpfendorfer, C.A. and Musick, J.A. |title=Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes |publisher=International Union for Conservation of Nature and Natural Resources |year=2005 |isbn=978-2-8317-0700-6 |pages=237–238}}</ref> Divers sometimes kill them for sport or to make jewelry out of their fin spines, which may be the cause of a decline in the numbers of horn sharks in the most intensely dived areas of southern California. Off Mexico, this species is caught incidentally in shrimp trawls and demersal [[gillnet]]s, and used for human consumption and fishmeal. The expansion of Mexican gillnet fisheries may pose a conservation concern in the future. At present, the [[International Union for Conservation of Nature]] (IUCN) does not have sufficient information to assess the overall conservation status of this species; its status in United States waters is likely [[Least Concern]].<ref name="iucn status 19 November 2021" />
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