which of the phyla come under complete digestive system?
Phyla with a true coelom and digestive system are divided into two groups, the protostomes and the deuterostomes. As the hollow sphere of cells known as a blastula develops, an invagination produces an opening called the blastopore. In protostomes, the blastopore becomes the mouth. In deuterostomes, the blastopore becomes the anus, and only later does a new opening form the mouth. The coelom also develops differently in the two groups. In protostomes, the mesoderm arises from cells located near the embryonic blastopore, and a splitting occurs that produces the coelom, called a schizocoelom. In deuterostomes, the coelom arises as a pair of mesodermal pouches from the wall of the primitive gut. The pouches enlarge until they meet and fuse, forming an enterocoelom. Protostomes include the phyla Mollusca, Annelida and Arthropoda. Deterostomes include the phyla Echinodermata, Hemichordata and Chordata.