Animals can be classified by three types of body plan symmetry: radial symmetry, bilateral symmetry, and asymmetry. Animals with radial symmetry have no right or left sides, only a top or bottom; these species are usually marine organisms like jellyfish and corals. Most animals are bilaterally symmetrical with a line of symmetry dividing their body into left and right sides along with a "head" and "tail" in addition to a top and bottom. Only sponges (phylum Porifera) have asymmetrical body plans. Some animals start life with one type of body symmetry, but develop a different type as adults; for example, sea stars are classified as bilaterally symmetrical even though their adult forms are radially symmetrical (3).