Discuss in detail the major changes in body plan & major organ systems & include any intermediate phyla that occurred as the invertebrates evolved into protostomes (Spiralia & Ecdysozoa) and deuterostomes (the Echinodermata, Hemichordata and the Chordata).

Discuss in detail the major changes in body plan & major organ systems & include any intermediate phyla that occurred as the invertebrates evolved into protostomes (Spiralia & Ecdysozoa) and deuterostomes (the Echinodermata, Hemichordata and the Chordata).