Plants and Animals

Valvata winnebagoensis Flanged valvata

Key Characteristics

The flanged valvata is a freshwater snail characterized by a small shell (to .2 inches diameter), with 3 prominently ribbed and angled whorls resembling stacked cylinders when viewed from the side. The spire is low and the aperature wide, of a semicircular shape. The snail itself features a single feathery gill on the left side and a tentacle on the right.

Status and Rank

US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G2? - Imperiled (inexact)
State Rank: SNR - Not ranked


CountyNumber of OccurrencesYear Last Observed

Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


This species can be found in cold, clean lakes and ponds (Minton 2004, Burch 1988).

Specific Habitat Needs

Clear water needed in: Great lake, littoral, benthic; Inland lake, littoral, benthic; Inland lake, pelagic, benthic.

Natural Community Types

  • Great lake, littoral, benthic
  • Inland lake, littoral, benthic
  • Inland lake, pelagic, benthic

For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Management Recommendations

Major changes to aquatic environments through impoundment, dredging and channelization can negatively affect aquatic snails through the fragmentation of populations and increased sedimentation, which can physically bury individuals and eliminate sources of food (Johnson 2009). Acidification of waterbodies decreases available calcium, sometimes resulting in thin-shelled snails, increasing vulnerability to predation (Brown 1991). Waters with a pH below 5 have been found incapable of supporting snail life (Okland 1992).  Acid rain reduction efforts will therefore be a positive step toward aquatic snail management.  Heavy metal and chemical pollution from agricultural and urban runoff, industrial waste, and pesticide treatment is lethal to many snail species, even at low exposure levels (Besser et al. 2007, Johnson 2009, Kosanke et al 2004). Efforts to improve water quality will benefit this group.

Active Period

Active from first week of June to first week of October

Survey Methods

There are several effective methods for conducting aquatic snail surveys. Areas of coarse cobble substrate are best surveyed with a glass-bottomed bucket or scuba search, and hand collecting. Stones and sunken pieces of wood can be picked up, searched, and replaced. Dip net suveys are employed at soft substrate locations. Aquatic vegetation held over a bucket and vigorously shaken to remove individual snails is another technique (Groves 2007).

D-frame net, dip net

Survey Period: From first week of June to first week of October

Time of Day: Daytime

Glass-bottom bucket less than waist deep water

Survey Period: From first week of June to first week of October

Time of Day: Daytime

SCUBA greater than waist deep water

Survey Period: From first week of June to first week of October

Time of Day: Daytime

Shaking vegetation survey

Survey Period: From first week of June to first week of October

Time of Day: Daytime


Survey References

  • Groves, K. 2007. Aquatic Spring Snail Survey and Habitat Analysis. USDA Forest Service.

Technical References

  • Besser, J.M., D.L. Hardesty, I.E. Greer, C.A. Mebane, D.R. Mount, and C.G. Ingersoll. 2007. Sensitivity of freshwater snails to contaminants: chronic toxicity tests with endangered species and surrogates. U.S. Geological Survey.
  • Brown, K.M. 1991. Mollusca: Gastropoda. Pp 285-314. In: Thorp, J.H. and A.P. Covich (eds.). 1991. Ecology and Classification of North Amercian Freshwater Invertebrates. Academic Press, Inc., San Diego, CA.
  • Burch, J.B. 1982. North American Freshwater Snails. Walkerana 1(4).
  • Burch, J.B. 1988. North American Freshwater Snails. Walkerana 2(6)
  • Johnson, P.D. 2009. Sustaining America's Aquatic Biodiversity: Freshwater Snail Biodiversity and Conservation. Virginia Cooperative Extension Publication 420-530.
  • Kosanke, G.J., W.W. Schwippert, and T.W. Beneke. 1988. The impairment of mobility and development in freshwater snails (Physa fontinalis and Lymnaea stagnalis) caused by herbicides. Comparative Biochemistry and Physiology Part C: Comparative Pharmacology 90(2):373-79.
  • Minton, R. 2004. Valvatidae. Pp 30-31. In: Perez, K.E., S.A. Clark and C. Lydeard (eds.). 2004. FMCS Showing Your Shells: A Primer to Freshwater Gastropod Identification. University of Alabama, Tuscaloosa, AL.
  • Okland, J. 1992. Effects of acidic water on freshwater snails: results from a study of 1000 lakes throughout Norway. Environmental Pollution 78(1-3):127-30.