PLANULA

plural Planulae, free-swimming or crawling larval type common in many species of the phylum Cnidaria (e.g., jellyfish, corals, and sea anemones). The planula body is more or less cylindrical or egg-shaped and bears numerous cilia (tiny hairlike projections), which are used for locomotion. Planulae are produced by both of the basic body forms found in cnidarianspolyps, the stalklike, attached adult forms, and medusae, the bell- or umbrella-shaped, free-swimming adult forms. See also polyp (zoology); medusa.