Chordate

Any member of the phylum Chordata, which includes the most highly evolved animals, the vertebrates, as well as the marine invertebrate cephalochordates (&see; amphioxus) and tunicates. All chordates, at some time in their life cycle, possess a dorsal supporting rod (notochord), gill slits, and a dorsal nerve cord.

Unlike vertebrates, tunicates and cephalochordates lack any kind of brain or skeleton. Chordate bodies consist of a body wall encasing a gut, with a space between called the coelom. The body is usually long and bilaterally symmetrical, with the mouth and sense organs at the front end.