Image from Teichlebewesen.

Gastrotrichs were once treated as a primarily freshwater taxon, but they are now know to be well represented in marine habitats as well. There are around 700 species, ca. 320 of which occur in fresh waters. In North America, there are about 70 species in three families, but these have been poorly studied (Balsamo et al., 2008).

The Phylum Gastrotricha are members of the now-useless phylum group of “pseudocoelomates.” These are minute animals (μm-mm) associated with benthic freshwater habitats. Like their better-known miniature cousins, the Rotifera, the gastrotrichs are typically parthenogenetic.

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Bibliography

• Balsamo, M., L. Guidi & J.-L. d'Hondt. 2013. Phylum Gastrotricha. In: Zhang, Z.-Q. (Ed.) Animal Biodiversity: An Outline of Higher-level Classification and Survey of Taxonomic Richness (Addenda 2013) . Zootaxa 3703(1): 079–082. [Available online]
• Zhang, Z.-Q. 2011. Animal biodiversity: An introduction to higher-level classification and taxonomic richness. Zootaxa 3148: 7-12. [Available online]
• Strayer, D.L., W.D. Hummon & R. Hochberg. 2010. Gastrotricha. [in] J.H. Thorp & A.P. Covich (eds.). Ecology and Classification of North American Freshwater Invertebrates, 3rd edition: 163-172.
• Balsamo, M., J.-L. d'Hondt, J. Kisielewski & L. Pierboni. 2008. Global diversity of gastrotrichs (Gastrotricha) in fresh waters. Hydrobiologia 595: 85-91. [Available online]
• Brusca, R.C. & G.J. Brusca. 2003. Invertebrates, 2nd edition. Sinauer Associates, Inc., Sunderland, Massachusetts. 936 pp.
• Smith. D.G. 2001. Gastrotricha. Pennak's Freshwater Invertebrates of the United States, 4th edition: 117-128.
• 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.
• Zakarija, J.L. 1980. Gastrotricha of Central Wisconsin. M.S. Thesis, Loyola University, Chicago. 85 pp.
• Rossino, G. 1979. Gastrotricha of Kettle Moraine State Park. M.S. Thesis, Loyola University, Chicago. 70 pp.
• Brunson, R.B. 1959. Gastrotricha. [in] W.T. Edmondson (ed.). Ward & Whipple Fresh-Water Biology, 2nd edition: 406-419.
• Pennak, R.W. 1940. Ecology of the microscopic Metazoa inhabiting the sandy beaches of some Wisconsin lakes. Ecological Monographs 10(4): 537-615. [Available online]

Student Essays

• "Weird Worms and The Tree of Life: The Relationship of Gastrotricha to Other Metazoan Phyla" by Madalyn Zimbric (BIOL/WATR 361, Fall 2012 )

Web Pages

• Animal Diversity Web
• Gastrotricha Overview
• Integrated Taxonomic Information System
• Micrographia Gallery
• Synopsis of the Described Gastrotricha of the World
• Systema Naturae 2000
• Tree of Life
• WikiSpecies
• Wikipedia
• World Register of Marine Species