Plants and Animals

Alasmidonta viridis Slippershell

Key Characteristics

The slippershell is a small (to 1.5 inches) mussel with a straight ventral margin. Beak sculpture has three to four ridges or loops. The lateral teeth are irregular and poorly developed; where as the cardinal teeth are triangular with one in the right valve and two in the left valve. The shell is yellowish-brown and marked with fine green rays with a square posterior end and a rounded anterior end. The nacre is white and often iridescent towards the posterior end of the shell.

Status and Rank

US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G4G5 - Rank is uncertain, ranging from apparently secure to secure
State Rank: S2S3 - Rank is uncertain, ranging from imperiled to vulnerable


CountyNumber of OccurrencesYear Last Observed
Alcona 2 1925
Allegan 2 2013
Alpena 3 1932
Barry 4 2013
Bay 1 Historical
Benzie 1 1925
Berrien 5 2009
Branch 3 2000
Calhoun 5 2018
Cass 3 1940
Cheboygan 1 2019
Chippewa 2 2007
Clare 4 2018
Clinton 6 2019
Crawford 4 1934
Delta 1 1930
Dickinson 6 2019
Eaton 6 2018
Emmet 1 2011
Genesee 2 2001
Gladwin 7 1981
Gratiot 2 2015
Hillsdale 23 2018
Huron 5 1942
Ingham 9 2018
Ionia 5 2016
Iosco 2 1937
Iron 1 Historical
Isabella 4 2019
Jackson 11 2017
Kalamazoo 1
Kent 15 2017
Lake 1 Historical
Lapeer 7 2016
Lenawee 14 2016
Livingston 12 2018
Luce 1
Mackinac 2 2007
Macomb 14 2007
Mecosta 2 1934
Menominee 11 2010
Midland 3 2012
Missaukee 5 2002
Monroe 10 2017
Montcalm 10 2015
Montmorency 3 1944
Muskegon 2 1936
Newaygo 3 1949
Oakland 18 2007
Oceana 1 1934
Ogemaw 6 2003
Osceola 9 2002
Oscoda 2 2016
Ottawa 1 Historical
Presque Isle 2 1940
Roscommon 3 1934
Saginaw 1 2011
Sanilac 5 2010
Schoolcraft 2 2018
Shiawassee 3 2001
St. Clair 11 2019
St. Joseph 5 2016
Tuscola 6 2011
Van Buren 8 2009
Washtenaw 18 2018
Wayne 8 1933
Wexford 2 1926

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.


The slippershell typically occurs in creeks and headwaters of rivers in sand or gravel substrates. Occasionally, they occur in larger rivers and lakes and in mud substrates.

Specific Habitat Needs

Sand, gravel substrates needed in: Headwater stream (1st-2nd order), riffle; Headwater stream (1st-2nd order), run; Inland lake, littoral, benthic; Mainstem stream (3rd-4th order), run; Mainstem stream (3rd-4th order), riffle.

Natural Community Types

  • Headwater stream (1st-2nd order), riffle
  • Headwater stream (1st-2nd order), run
  • Inland lake, littoral, benthic
  • Mainstem stream (3rd-4th order), run
  • Mainstem stream (3rd-4th 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

The slippershell requires clear, clean water and substrates for survival. Like other mussels, threats include: siltation, poor water quality, point and non-point source pollution, and alteration of natural flow regimes. Maintenance or establishment of vegetated riparian buffers can help protect mussel habitats from these threats. Additionally, zebra mussels and other exotic species are a major threat to all mussels. Hence, control and management of exotic species also help protect native mussel species. And as with all mussels, protection of their hosts habitat is also crucial.

Survey Methods

Glass-bottom bucket less than waist deep water

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

SCUBA searches

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

Snorkeling searches

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


Survey References

  • Cummings, K.S. and C.A. Mayer. 1992. Field Guide to Freshwater Mussels of the Midwest. Illinois Natural History Survey Manual 5, Champaign. 194pp.
  • Strayer, D.L. and D.R. Smith. 2003. A Guide to Sampling Freshwater Mussel Populations. American Fisheries Society Monograph 8, Bethesda. 103pp.

Technical References

  • Carman, S.M. 2002. Special Animal Abstract for Alasmidonta viridis (Slippershell mussel). Michigan Natural Features Inventory, Lansing, MI. 3pp.
  • Clarke, A.H. 1981. The Freshwater Molluscs of Canada. National Museum of Natural Science, National Museums of Canada, Ottawa. 446pp.
  • Cummings, K.S. and C.A. Mayer. 1992. Field Guide to Freshwater Mussels of the Midwest. Illinois Natural History Survey Manual 5, Champaign. 194pp.
  • Dillon, R.T. Jr. 2000. The Ecology of Freshwater Molluscs. Cambridge University Press, Cambridge, UK. 509pp.
  • Oesch, R.D. 1984. Missouri Naiades: a Guide to the Mussels of Missouri. Conservation Commision of the State of Missouri, Jefferson City. 270pp.