Become jaws, inner ear, and tonsils in terrestrial chordates. A tail located posterior to the anal opening. The Phylum Chordata includes all of the vertebrates, as well as two groups of marine animals that lack backbones and are therefore invertebrates. They retain the notochord, dorsal nerve chord, pharyngeal pouches, and postanal tail throughout their life. They are also known as sea squirts because they shoot out a stream of water when touched.
Most tunicates are sessile, barrel-shaped, filter feeding animals that live on the sea bottom.
Adult tunicates have a pouch-like pharynx with slits, but they do not have a notochord, dorsal nerve cord, or postanal tail. These chordate characteristics are lost during metamorphosis. The phylum is named for the vertebrae. Skull - bones protecting the brain. Backbone - bones protecting the nerve cord and supporting the body.