A freshwater Bryozoan, species unknown.
  • Bryozoa
  • Name Meaning: Moss animals
  • English Common Name: Moss animals, sea mats, bryozoans
  • Major distinguishing characteristics: Lophophore, no pedicle, ciliated tentacles
  • Approximate number of species described: about 5,000 living species

Natural History


All bryozoans are aquatic filter feeders. They are usually sessile, attaching themselves to rocks or plants. All but one genus is colonial. Most bryozoans are marine, only one Class has freshwater species.



There are three Classes currently recognized within the Phylum Bryozoa.

  • Phylactolaemata
  • Stenolaemata
  • Gymnolaemata



Bryozoans are soft-bodied invertebrates. They possess a lophophore surrounding the mouth. Several short tentacles with cilia are on the lophophore, which save in the water to direct water into the mouth for feeding.

The Fossil Record


Bryozoans do not appear in the fossil record until the Ordovician (488.3 - 443.7 million years ago). They are soft-bodied and fossils are rare. It's possible they live prior to that time.



References and Further Reading

  • Bryozoa on Wikipedia
  • Bryozoa at the University of California Museum of Paleontology
  • Bryozoa from Encyclopedia of Life
  • Bryozoa at Tree of Life