Into which subphyla are the protochordates divided? What are some representatives of each protochordate subphylum?
Cephalochordates and Urochordates (or tunicates) are the two subphyla into which protochordates are divided.
Ascidians, sessile animals similar to sponges, are instance of tunicates. The amphioxus, well-studied in Embryology, is an instance of cephalochordate.