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