The Mexican hornshark (Heterodontus mexicanus) is a Bullhead shark belonging to the family Heterodontidae. This shark is grey-brown in color, with black spots dispersed on the fins and body. They are typically found from Mexico to Colombia. However, there are reports elsewhere north and south of this range.
Family: Heterodontidae – Bullhead Sharks
Genus: Heterodontus
Species: mexicanus
Phylum– Chordata
Class– Chondrichthyles
Subclass– Elasmobranchii
Infraclass– Euselachii
Superorder– Selachimorpha
Common Name– Bullhead Sharks
Family– Heterodontidae
Common Name– Bullhead Sharks
Genus– Heterodontus
Species– mexicanus
Status: IUCN Red List DATA DEFICIENT
Average Size and Length: They are born around 14 cm/ 5.5 inches. Mature males are between 1.3-1.6 feet. The maximum recorded length of a male is 1.8 feet. Females have been measured at 2.3 feet.
The egg case measures between 8-9 cm.
Teeth and Jaw: Their mouths open anteriorly. The teeth at the front of the jaws are small and pointed with a central cusp and two lateral cusplets, while those at the back of the jaws are wide and molar-like.
Head: The head of the Mexican hornshark is conical. The snout of the Mexican hornshark is very round and blunt. There are small spiracles behind the eyes. The supraorbital ridges are low which do not end abruptly behind the eyes.
Denticles: They have small denticles on their flank that are rough to the touch.
Tail: Their caudal fin is asymmetric.
Demographic, Distribution, Habitat, Environment and Range: The Mexican hornshark can be found in the east Pacific from Mexico to Colombia and possibly in Ecuador and Peru. They can be found in rock, coral reefs, sand and seamounts from close inshore to between 66-164 feet.
Diet: They more than likely feed on crabs and demersal fish.
Ram-Suction Index: This is not confirmed, but more than likely they have a combination of suction like their family members. The shape of their jaw would indicate that it may protrude to grab unknowing prey like its family members.
Aesthetic Identification: The Mexican hornshark is light grey-brown to dark grey. Ventrally they become almost white. They have large black spots that are greater than half of the eye diameter. There is a light bar between the eye ridges, there are 1 or 2 indistinct blotches under the eyes. They have five gill slits, the first of which is enlarged and the second and third of which are over their pectoral fins. The trunk is cylindrical in shape. It has fin spines in front of both of its dorsal fins. The origin of the first dorsal fin is over the pectoral fin bases. The second dorsal fin originates behind the pelvic fins. The pectoral fins are very large.
Biology and Reproduction: The Mexican hornshark is oviparous. Not much else is known about the specifics of their biology and reproduction in comparison to other members of its family.
The egg cases are auger-shaped and have long tendrils and rigid “T” shaped spiral flanges. There are 5 visible turns. The tendrils may aid in anchoring the egg cases. At first the case is soft and light brown, and over a few days it hardens and darkens in color.
Behavioral Traits, Sensing and Intelligence: Not much is known of their behavior, but they ma have similar characteristic like that of their family.
Speed: Their movement is not confirmed; however, they more than likely move similar to that of their family members. The large pectoral fins may aid in “walking” along the bottom, and they are more than likely slow, sluggish swimmers.
Mexican Hornshark Future and Conservation: There is not enough data to evaluate the Mexican hornshark. They are of very little interest to commercial fisheries. On occasion it is taken as bycatch. Sometimes it is released, and other times it is processed and used as fishmeal. This is a resilient shark, so typically when it is released back, its chance of survival is strong; however, many times it is found discarded on beaches left to die.
Mexican Hornshark Recorded Attacks on Humans: Harmless to humans (unless stressed), the Mexican hornshark poses no threat. Their spines can impose a painful wound if not careful.