This lifeform is widespread, but not common.

Bonnethead Shark(Sphyrna tiburo) is found in the Atlantic Ocean from New England to Argentina. The Bonnethead is also found in the eastern Pacific Ocean. This small species is less than five feet in length.

Hammerhead Sharks (Family Sphyrnidae) are a group of marine sharks that prefer warmer waters. The unusual head shape of the Hammerheads has side lobes where the eyes are mounted. There are eight living species of Hammerheads. The following species are typical of the family:

    Scalloped Hammerhead   Sphyrna lewini    Worldwide
    Great Hammerhead       Sphyrna mokarran  Worldwide
    Bonnethead             Sphyrna tiburo    Atlantic & Pacific
    Smalleye Hammerhead    Sphyrna tudes     Atlantic & Pacific
    Smooth Hammerhead      Sphyrna zygaena   Worldwide

Scalloped Hammerheads can be found as far north as New Jersey; the Great Hammerhead as far north as the Carolinas; the Bonnethead as far north as New England; the Smalleye into the Gulf of Mexico, and the Smooth Hammerhead as far north as New England.

True Shark group (Order Lamniformes) contains the majority of the world's species of living sharks. They are characterized by  having five gill slits. Some taxonomists recognize over fifteen families in this order.

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.