This lifeform is found in the Pacific Ocean near Mexico.

Mexican Horn Shark (Heterodontus mexicanus) is found in the Gulf of Mexico which lays between Baja California and Mexico. This species is also found in the eastern Pacific Ocean from Mexico south to Colombia.

Bullhead Sharks (Family Heterodontidae) are found in the Indian and Pacific Oceans and appear to be absent from the Atlantic Ocean. This is a ancient family of sharks. There are only about nine or ten species remaining. The two dorsal fins, each with a leading spike, helps identify these sharks.

Heterodonitformes order (Bullhead sharks) now contains a single family. This is an ancient order with many known fossil species.

Sharks and rays (Elasmobranchi), cartilaginous fishes, deserve to be a class separate from the normal fish, in that they do not have a bone skeleton but rather a cartilage skeleton.

Fertilization is internal in this class which also separates them from the bony fish class. Although there are a few fresh water species, the majority of the species in this class are found in salt water. As of 2005, there were about 500 known species of sharks and about 600 known species of rays.

David Ebert, author of a recent book on sharks, rays, and chimaeras of California, counts a total of 988 described species in the class with about 150 additional species awaiting scientific description. He breaks down the described species to 410 species of sharks, 543 species of rays, and 35 species of chimaeras.

Backboned Animals (Phylum Chordata) are the most advanced group of animals on earth. These animals are characterized by having a spinal cord or backbone. Most members have a clearly defined brain that controls the organism through a spinal cord. Fish, amphibians, reptiles, birds, and mammals are in this phylum.

Currently, some taxonomists believe that the fish should be divided into two groups (sharks and regular fishes) and that there are some other primitive groups in the phylum such as hagfish or lampreys.

Animal Kingdom contains numerous organisms that feed on other animals or plants. Included in the animal kingdom are the lower marine invertebrates such as sponges and corals, the jointed legged animals such as insects and spiders, and the backboned animals such as fish, amphibians, reptiles, birds, and mammals.