Question

The derived characteristic of protostome development is found in which of the following phyla?

A. Sponges B. Roundworms C. Cnidarians D. Echinoderms

Answer 1

The answer is B. Roundworms. Protostome creatures are divided into three groups, and nematoda or roundworms are under the Ecdysozoa group, together with arthropods (spiders etc.)

Answer 2

The correct answer is roundworm.

The evolution of worm like aquatic animals led to the formation of protostome. During development the first opening develops into mouth and the anus forms secondarily. This kind of a structure is seen in the roundworm.The common ancestors was evidently worm like aquatic animals.The phylum such as nematoda, mollusca, annelida and arthopods have prostostome developed body.