Phylactolaemata, the freshwater bryozoans, is one of the three classes of the phylum Bryozoa. Representing small percentage of the bryozoan diversity, this group is made up of 74 described species, 59 of which belong to family Plumatellidae. All Phylactolaemata species live only in fresh water, in sessile colonies of genetically identical individuals called zooids. Although bryozoans in other classes have colonies comprised of different types of zooids, all Phylactolaemata species have only the feeding autozooids, and they are characterized by an un-mineralized, gelatinous or protinaceous exoskeleton (Hartikainen et al. 2013). Colonies, which can be encrusting or branched, usually attach to surfaces in still or running waters. While they reproduce sexually, genetic individuals can persist in non-ideal environmental conditions such as freezing or desiccation by producing dormant “statoblasts,” masses of cells generated asexually, often in huge numbers, and protected with chitinous shells. Statoblasts can disperse long distances and develop into a colony-forming zooid in more favorable conditions (Ruppert et al. 2004; Wikipedia 2013). Many freshwater bryozoan species grow rapidly, so are often found in large abundance. Species of phylactolaemata have been studied as important in nutrient cycling, as agents causing biofouling problems, as creators of habitats for other species, and as a hosts for a parasite destructive to salmonid fish (Hartikainen et al. 2013 and references therein).
- Hartikainen, H., A. Waeschenbach, E. Wöss, T. Wood, and B. Okamura 2013. Divergence and species discrimination in freshwater bryozoans (Bryozoa: Phylactolaemata). Zoological Journal of the Linnean Society 168(1):61–80.
- Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004). "Lophoporata". Invertebrate Zoology (7 ed.). Brooks / Cole. pp. 829–845. ISBN 0-03-025982-7.
- Wikipedia, The Free Encyclopedia. 24 March 2013. Phylactolaemata. Retrieved August 1, 2013 from http://en.wikipedia.org/w/index.php?title=Phylactolaemata&oldid=546736021