The horn shark, Heterodontus francisci, is a bullhead shark. It can reach a size of 121 cm (4 ft) and weigh 10 kg (22 lb). It is brown with black spots. Its range is from central California to the Gulf of California, Mexico, and probably also in Ecuador and Peru. It is mostly nocturnal and appears sluggish in the daytime. It can bite if it is harassed.

Its habitat includes rocky reefs, kelp beds, sand flats, crevices, and caverns in a depth range from 2 to 150 m. Adults tend to return to the same resting spot every day. It feeds on invertebrates, primarily sea urchins, crabs, probably abalone, and fish.