Plants and Animals

Helisoma anceps royalense Lake Superior ramshorn

Key Characteristics

The Lake Superior ramshorn shell is discoidal and concave on both sides with 2-3 finely striated whorls, semi-glossy and light brown in color, and up to about .4 inches in diameter. The aperature is large and semicircular and the spire is inverted.

Status and Rank

US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G5T2T3
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 is found among dense vegetation in large lakes and rivers with sand or gravel substrates (O'neal and Soulliere 2006).

Specific Habitat Needs

Aquatic vegetation needed in: Great lake, littoral, benthic; Great lake, pelagic, benthic; Inland lake, littoral, benthic; Inland lake, pelagic, benthic; River (5th-6th order), pool; River (5th-6th order), run; River (5th-6th order), riffle.

Natural Community Types

  • Great lake, littoral, benthic
  • Great lake, pelagic, benthic
  • Inland lake, littoral, benthic
  • Inland lake, pelagic, benthic
  • River (5th-6th order), pool
  • River (5th-6th order), run
  • River (5th-6th order), riffle

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

74% of North American freshwater snail species are either extinct, endangered, threatened or vulnerable (Johnson et al. 2008). Major threats include habitat loss, sedimentation, and population fragmentation from dredging, channelization, impoundments and other construction projects on or near waterways. Lakes and rivers with increased pH levels from acid rain are incapable of supporting healthy snail populations (Okland 1992, Shaw and Mackie 2011). Additionally, contaminated water from agricultural and urban runoff, industrial waste, pesticide application and other forms of point and non-point source pollution can be fatal to adult snails and prevent reproduction (Besser et al. 2007, Johnson 2009). Efforts to protect this imperiled group should therefore center around the preservation and restoration of aquatic habitats as well as pollution reduction.

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.
  • Burch, J.B. 1982. Freshwater Snails (Mollusca: Gastropoda) of North America. EPA Report 600/3-82-026. Environmental Monitoring and Support Laboratory, Office of Research and Development, Enviornmental Protection Agency, Cincinnati. 294 pp.
  • Johnson, P.D. 2009. Sustaining America's Aquatic Biodiversity: Freshwater Snail Biodiversity and Conservation. Virginia Cooperative Extension Publication 420-530.
  • Johnson, P.D., A.E. Bogan, K.M. Brown, J. Garner, P.D. Hartfield, E.E. Strong, and J.R. Cordeiro. 2008. Finalizing a Conservation Assessment for North American Freshwater Gastropods. In: Anderson, F.E., M. Coppolino, and S. Clutts (eds.). 2008. Program and Abstracts, 74th Annual Meeting , American Malacological Society, Carbondale, Illinois. 105 pp.
  • O’Neal, R. P., and G. J. Soulliere. 2006. Conservation guidelines for Michigan lakes and associated natural resources. Michigan Department of Natural Resources, Fisheries Special Report 38, Ann Arbor.
  • 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.
  • Shaw, M.A. and G.L. Mackie. 1990. Effects of Calcium and pH on the Reproductive Success of Amnicola limosa (Gastropoda). Canadian Journal of Fisheries and Aquatic Sciences 47:1694-99.