What are Bryozoans?
Bryozoans, also known as moss animals or sea mats, are encrusting colonial animals found throughout the world’s oceans. They prefer warm, tropical water. Bryozoans have their own phylum, Bryozoa, which is a member of the superphylum Lophotrochozoa, the lophophorates. What all members of this group have in common is that they use a characteristic horseshoe-shaped, cylinder-shaped, or coiled ciliated feeding organ called a lophophore. Lophophores are used for filter feeding and evolved from a simple ring of cilia around the mouth. Most bryozoans are stationary, though some colonies can creep around, and at least one species is free-floating. To protect themselves, most bryozoans surround their soft parts with a stony calcium carbonate exoskeleton, like coral does. This skeleton can often be found encrusting mollusk shells found on a beach, and can be scraped off by rubbing the shell with a finger under running water. Some species of bryozoan don’t build skeletons, and are instead held to
Bryozoans are also known as moss animals for their superficial resemblance to mosses. What we see as a bryozoan is really a colony made of many little units, each made up of the animal and its house. Bryozoans are closely related to the brachiopods. Both groups possess a unique feeding and respiratory organ called a lophophore, which looks a bit like a rubber band covered with tiny hairs. By moving the hairs, they generate a current that brings water and food particles to the animal. Most bryozoans live attached to a hard surface, such as mussels, rocks, wood, sea turtle shells, or large algae. Many Paleozoic bryozoans built strong colony skeletons of calcium carbonate and are common fossils. First known fossil occurrence: Ordovician.Last known fossil occurrence: Quaternary. This group has living relatives.
