A coelom is a true body cavity. An acoelomate body plan lacks a body cavity. An example of a coelomate body plan is seen in an earthworm. It has a digestive tract located inside a body cavity. However, a tapeworm has no body cavity. Radial symmetry is a body plan organized around a circle as seen in slices of a pie. Each slice is pretty similar to the next. An example is the symmetry seen in starfish. Their arms or rays resembles spokes on a wheel and they have a round symmetry. A person exhibits bilateral symmetry. The left side of the body resembles the right side like a mirror image. A protostome is an animal whose mouth is formed from the blastopore in the embryo and includes most invertebrates. A deuterostome is an animal whose anus is formed from the blastopore and includes Echinoderms and all vertebrates.