Image from Indexes to Bryozoan Taxa.

The Phylum Bryozoa (“moss animals”) is a group of minute (μm-mm) colonial tentacle-feeders found predominantly in marine habitats, but the taxon is also found in fresh waters. Of the c. 4000 global species, about 90 are found in inland habitats. The majority of these belong to the Phylactolaemata, a strictly freshwater class (Massard & Geimer, 2008). Thirty two species are known from North America.

Bryozoans, also known as ectoprocts, are zoologically significant for their phylogenetic affinities. The phylum belongs to a larger group diagnosed by the possession of a lophophore -- a distinctive, U-shaped arrangement of anterior tentacles. Lophophorates also have a U-shaped gut, with the mouth surrounded by the lophophore and the anus outside the tentacles. (There are no other U-shaped organs.) The lophophorate phyla had traditionally been regarded as deuterostomes (the only freshwater invertebrate representatives) based on their patterns of early development. However, modern phylogenetic work places these taxa, including the bryozoans, among the protostomes.

In fresh waters, phylactolaemate bryozoans are distinctive for their large gelatinous colonies and the asexual production of over-wintering stages called statoblasts.

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Bibliography

• Bock, P.E. & D.P. Gordon. 2013. Phylum Bryozoa Ehrenberg, 1831. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) . Zootaxa 3703(1): 067–074. [Available online]
• Zhang, Z.-Q. 2011. Animal biodiversity: An introduction to higher-level classification and taxonomic richness. Zootaxa 3148: 7-12. [Available online]
• Wood, T.S. 2010. Bryozoans. [in] J.H. Thorp & A.P. Covich (eds.). Ecology and Classification of North American Freshwater Invertebrates, 3rd edition: 437-454.
• Massard, J.A. & G. Geimer. 2008. Global diversity of bryozoans (Bryozoa or Ectoprocta) in freshwater. Hydrobiologia 595: 93-99. [Available online]
• Smith, D.G. 2001. Ectoprocta (Moss animals). Pennak's Freshwater Invertebrates of the United States, 4th edition: 249-268.
• Underhill, J.C., W.D. Schmid & D.E. Gilbertson. 1982. Taxonomic Keys to the Common Animals of the North Central States, exclusive of the parasitic worms, terrestrial insects, and birds, 4th edition. 205 pp.
• Rogick, M.D. 1959. Bryozoa. [in] W.T. Edmondson (ed.). Ward & Whipple Fresh-Water Biology, 2nd edition: 495-507.

Student Essays

• "Factors Affecting the Viability of Bryozoan Statoblasts" by Anna G. Radke (BIOL/WATR 361, Spring 2015 )

Web Pages

• Animal Diversity Web
• Dutch freshwater bryozoans (moss animals)
• Indexes to Bryozoan Taxa
• Integrated Taxonomic Information System
• Recent and Fossil Bryozoa
• Tree of Life
• WikiSpecies
• Wikipedia
• World Register of Marine Species