Start studying Cnidarians, Echinoderms, and Sponges. Learn vocabulary, terms, and more with flashcards, games, and other study tools. read more
Best Answer: Cnidarians are very primitive organisms, and echinoderms are much more derived. This is the simplest point of the problem. To get more advanced, the echinoderms have actually secondarily derived a radial symmetry from a bilateral one (their larvae are bilateral). read more