A phylum of aquatic, mainly marine, invertebrates comprising the moss animals and sea mats. Bryozoans live in colonies, 50 cm or more across, which are attached to rocks, seaweeds, or shells. The individuals (zooids) making up the colonies are about 1 mm long and superficially resemble cnidarian polyps, with a mouth surrounded by ciliated tentacles of the lophophore that trap minute particles of organic matter in the water. Some have a horny or calcareous outer skeleton into which the body can be withdrawn. Bryozoans are placed in the clade of protostome animals called the Lophotrochozoa. Compare Entoprocta.
Subjects: Biological Sciences.