Image from Biopix.

The Gastropoda (snails and slugs) is the most species-rich class of the Phylum Mollusca. Although estimates vary, some number (much) greater than 40,000 species in marine, terrestrial, and freshwater environments is appropriate. About 4000 species of snails are found in the fresh and “freshened” waters of the world. Of these, 585 are reported from North America (Strong et al., 2008).

Gastropods possess radulae and coiled calcium carbonate shells, in addition to “torsion” during development. The freshwater snails represent two major radiations. The caenogastropods are operculate snails typically found in rivers as well as lakes. Multiple families have invaded fresh waters from estuarine and marine habitats. In contrast, the pulmonate pond snails are air-breathers that invaded lakes and rivers from terrestrial habitats.

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Bibliography

• Johnson, P.D., A.E. Bogan, K.M. Brown, N.M. Burkhead, J.R. Cordeiro, J.T. Garner, P.D. Hartfield, D.A.W. Lepitzki, G.L. Mackie, E. Pip, T.A. Tarpley, J.S. Tiemann, N.V. Whelan & E.E. Strong. 2013. Conservation Status of Freshwater Gastropods of Canada and the United States. Fisheries 38(6): 247-282.
• Brown, K.M. & C. Lydeard. 2010. Mollusca: Gastropoda. [in] J.H. Thorp & A.P. Covich (eds.). Ecology and Classification of North American Freshwater Invertebrates, 3rd edition: 277-307.
• Strong, E.E., O. Gargominy, W.F. Ponder & P. Bouchet. 2008. Global diversity of gastropods (Gastropoda; Mollusca) in freshwater. Hydrobiologia 595: 149-166. [Available online]
• Smith, D.G. 2001. Mollusca (Gastropods, pelecypods). Pennak's Freshwater Invertebrates of the United States, 4th edition: 327-400.
• 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.
• Clench, W.J. & S.L.H. Fuller. 1965. The genus Viviparus (Viviparidae) in North America. Occasional Papers on Mollusks 2(32): 385-412. [Available online]
• Clench, W.J. 1962. A catalogue of the Viviparidae of North America with notes on the distribution of Viviparus georgianus Lea. Occasional Papers on Mollusks 2(27): 261-287. [Available online]
• Clench, W.J. 1959. Mollusca. [in] W.T. Edmondson (ed.). Ward & Whipple Fresh-Water Biology, 2nd edition: 1117-1160.
• Baker, F.C. 1928. The fresh water Mollusca of Wisconsin. Part I. Gastropoda. Bulletin of the Wisconsin Geological and Natural History Survey 70(1): i-xx, 1-507.

Student Essays

• "Freshwater Pulmonate (Mollusca: Gastropoda) Reproduction" by Rachel Sommer (BIOL/WATR 361, Fall 2013 )
• "Parthenogenesis in populations of Campeloma decisum" by Caitlin M. Luebke (BIOL/WATR 361, Fall 2013 )
• "Eradicating Schistosomiasis at a Snail’s Pace" by Gloria Lorenz (BIOL 490, Fall 2014 )

Web Pages

• A Wisconsin Bestiary
• Animal Diversity Web
• Integrated Taxonomic Information System
• Tree of Life
• WikiSpecies
• Wikipedia
• Wisconsin's Rare Aquatic and Terrestrial Snails
• World Register of Marine Species