AP BIOLOGY

Detailed explanation-1: -In protostomes, the site of gastrulation is said to give rise to the mouth, while in deuterostomes it forms the anus with the mouth arising from a second opening distant to the site of gastrulation. (A) Phylogenetic relationship of major metazoan groups.

Detailed explanation-2: -Protostomes include arthropods, mollusks, and annelids.

Detailed explanation-3: -The mouth of the Protostomia (proto, “first”; stoma, “mouth”) develops from the first opening into the embryonic gut (blastopore). The coelom (body cavity) forms from a split in the embryonic mesoderm (middle tissue).

Detailed explanation-4: -Protostome and deuterostome are terms for members of major taxonomic groups of animals categorized by how they develop as embryos. In protostomes, the first opening in the embryo becomes the mouth. In deuterostomes, the first opening in the embryo becomes the anus, and the mouth develops later.