Bryozoa (Ectoprocta; moss-animals) A phylum of small, aquatic, colonial animals, related to the Brachiopoda, many of which possess a well-developed, calcite skeleton which comprises microscopic, box-like divisions each housing an individual animal possessing ciliated tentacles and a coelom. Food is collected by the tentacles which surround the mouth and are borne on the lophophore. Reproduction takes place by asexual budding, and by the release of larvae which give rise to new colonies. Bryozoans have occurred from the Ordovician to the present day. Fossilized branched colonies are common in some rocks. They were important reef builders in the Phanerozoic, and underwent several great adaptive radiations.

Bryozoa (moss-animals) Phylum of small, aquatic, colonial animals, related to the Brachiopoda; many colonies possess a well-developed, calcite skeleton which comprises microscopic, box-like divisions, each housing an individual animal possessing ciliated tentacles and a coelom. Food is collected by the tentacles which surround the mouth and are borne on a ridge called the ‘lophophore’. Reproduction takes place by (a) asexual budding, and (b) the release of larvae which give rise to new colonies. There is a possible bryozoan fossil from the Late Cambrian, and bryozoans have occurred abundantly from the Ordovician to the present day. Branched colonies are common fossils in some rocks. They were important reef builders and binders in the Phanerozoic, and underwent several great radiations. See ECTOPROCTA

Bryozoa(Ectoprocta; moss animals) A phylum of small, aquatic, colonial animals, related to the brachiopods, many of which possess a well-developed, calcite skeleton which comprises microscopic, box-like divisions, each housing an individual animal possessing ciliated tentacles and a body cavity (coelom). Food is collected by the tentacles which surround the mouth. Reproduction takes place by asexual budding and by the release of larvae which give rise to new colonies. Bryozoans have occurred from the Ordovician to the present day. Fossilized branched colonies are common in some rocks. They were important reef-builders in the Phanerozoic, and underwent several great adaptive radiations.

Bryozoa (Ectoprocta) 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. Compare Entoprocta.

Bry·o·zo·a / ˌbrīəˈzōə/ Zool. a phylum of sedentary aquatic invertebrates that comprises the moss animals. DERIVATIVES: bry·o·zo·an n. & adj.