The phylum of the animal kingdom that includes sea urchins is Echinodermata. They are marine animals that have a star-like characteristics. Sea urchins are described as spiny, globular echinoderms.
Porifera are sponges. Phylum Cnideria inlcudes the corals, hydras, and jelly fish. Mesozoa are worm-like parasites of marine invertebrates.
Answer - Option 3 - echinidermata