Sub-phylum Urochordata are known as sea-squirts, adults are mostly marine and fixed, body is covered by test/tunic, notochord & nerve cord are found in the larvae and are lost and reduced to a ganglion in the adult.
Example: Herdmania.
Sub -phylum cephalochordata have fish like body, notochord and nerve cord are present throughout, eyes, nose, ears and jaws are absent, butarimal represents the fundamental plan of the chordate body in a simple form. Example: Amphioxus.
