This lifeform is found widely in the Atlantic Ocean. This lifeform is found widely in the Pacific Ocean. This lifeform is very common in suitable environments.

Sand Tiger (Carcharius taurus = Odontaspis taurus = Eugomphodus taurus) is found on the Atlantic Coast from New England south to Argentina, near Europe, and also in the Pacific Ocean, especially near Australia. The two large dorsal fins are about the same size. The Sand Tiger can be up to ten feet in length. This species is locally common.

Sand Sharks (Family Odontaspidae) are found worldwide. These sharks have two dorsal fins of almost the same size and five gill slits. The following species are typical of the family:

   Odontaspis arenarius    Gray Nurse Shark    Warm Oceans
   Odontaspis taurus       Sand Tiger          Widespread
   Odontaspis ferox        Bumpy Tail          Widespread
   Odontaspis noronhai     Big Eye Sand Tiger  Widespread

There are contradictions regarding the placement of O. arenarius. There is also a difference of opinion as to the validity of various species.

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.