This lifeform is found east of the Continental Divide in North America. This lifeform is found in freshwater such as lakes or rivers.

Least Brook Lamprey (Lampetra aepyptera) is found in the eastern United States in some rivers that drain into the Atlantic and the Mississippi. Known populations exist in Pennsylvania, North Carolina, Georgia, Alabama, Arkansas, and Missouri. The two dorsal fins, non-parasitic nature, and extremely degenerate disk teeth help identify this species. Atlantic Coast specimens can be up to seven inches long, while the Mississippi drainage specimens are usually less than five inches in length.

Lampreys (Class Petromizontiformes) are a group of ancient boneless fish-like creatures with a cartilaginous skeleton, a spinal cord, and no jaws. Some species are totally freshwater, and others have life cycles that involve both marine and freshwater. Lampreys generally have eyes, seven external gill slits, and a funnel-like mouth. Many lampreys are parasitic on other fish, and some are free living. There are about forty species of lamprey found worldwide. About twenty species are found in North America. The Lampreys are found in both the northern and southern hemispheres in the Old and New World.  There are no tropical species.

Agnatha Class contains the lampreys and hagfish. They are characterized by having a sucking mouth and the lack of a lower jawbone. Although most older biology books separate the phylum chordata into five major classes (fish, amphibians, reptiles, birds, and mammals), recent thinking has been to divide the fish group into three separate classes (lamprey, sharks & rays, and normal bony fish).

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.