|Scientific field drawing|
L. R. Taylor & Castro-Aguirre, 1972
|Range of Mexican bullhead shark (in blue)|
The Mexican hornshark, Heterodontus mexicanus, is a bullhead shark of the family Heterodontidae. This shark is grey-brown in color, with black spots scattered on the fins and body. It has a cylindral trunk, conical head, and small spiracles behind the eyes. The snout of the Mexican hornshark is very round and blunt. Like all members of the order Heterodontiformes, this shark has fin spines in front of both of its dorsal fins. The first dorsal fin originates before the pectoral fins, while the second dorsal fin originates behind the pelvic fins. The Mexican hornshark reaches a maximum length of around 70 cm, but usually reaches between 50 and 60 cm on average. Young hornsharks hatch at around 14 cm. 
Habitat and Range
Mexican hornsharks are distributed throughout the coast of the Eastern Pacific, mainly around southern Baja California, and possibly as south as Peru. The rocky bottoms, coral reefs, and sandy areas of the littoral zone create the habitat of this hornshark. The Mexican hornshark can be found at a maximum depth of 50 meters, but are usually found down to 20 meters.
Like all members of the order Heterodontiformes, the Mexican hornshark is oviparous. After an unknown gestation period, the female attaches an unknown number of spiral-shaped egg cases to rocks on the sea floor. The length of the incubation period of these egg cases is also unknown. Not much about the feeding habits of the Mexican hornshark is known, but it is very likely they feed on shelled invertebrates. Because of its size, this shark poses no danger to humans.
Because of its recent discovery and lack of research, the Mexican hornshark is listed as Data Deficient by the IUCN Red List. This shark is not considered to have commercial value, but it is at risk nonetheless because it is taken as by-catch by fishing operations that use bottom gillnets. Mexican hornsharks caught as by-catch are either discarded or used in fishmeal. If released back into the water, these sharks are hardy enough to survive, but unfortunately many discarded hornsharks are left on beaches to die. Overall, the threat to Mexican hornsharks is considerable, as their range is restricted and they are frequently caught as by-catch. 
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Heterodontus mexicanus" in FishBase. May 2006 version.