Plants and Animals

Pleurobema clava Clubshell

Key Characteristics

The clubshell is a medium sized (to 3.5 inches), wedge-shaped mussel tapering towards the posterior end. The beak is located close to the anterior end of the shell. Beak sculpture consists of a few small bumps or loops or is absent. The lateral and cardinal teeth are well developed. The shell is tan or yellow with broad, dark green rays that are almost always present and are interrupted at the growth rings. There is often a crease or groove near the center of the shell running perpendicular to the annular growth rings. The nacre is white.

Status and Rank

US Status: LE - Listed Endangered
State Status: E - Endangered (legally protected)
Global Rank: G1G2 - Rank is uncertain, ranging from critically imperiled to imperiled
State Rank: S1 - Critically imperiled


CountyNumber of OccurrencesYear Last Observed
Hillsdale 13 2022

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 Clubshell is found in small to medium streams with gravel/sand substrate and relatively little silt. It occurs most often in runs with laminar flow (0.06-0.25 m/sec). Mean summer chemical measures from clubshell habitat in the St. Joseph River, Michigan were as follows: pH (8.1), conductivity (478 mS), and dissolved oxygen (8.6 mg/liter).

Specific Habitat Needs

Coarse sand and gravel substrates needed in: Mainstem stream (3rd-4th order), run; Mainstem stream (3rd-4th order), riffle; River (5th-6th order), run; River (5th-6th order), riffle.

Natural Community Types

  • Mainstem stream (3rd-4th order), run
  • Mainstem stream (3rd-4th order), riffle
  • 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

The clubshell is extirpated from most of its range and is now restricted mainly to headwater stretches of its former habitat. In 1993, the USFWS determined that the clubshell’s range had been reduced by 95%. The decline has been mainly due to pollution from agricultural runoff and alteration of natural flows. In addition, this species is especially sensitive to siltation. Maintenance or establishment of vegetated riparian buffers can help protect mussel habitats from many of their threats. However, a watershed approach is needed to help conserve this 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

  • Badra, P.J. 2001. Special Animal Abstract for Pleurobema clava (Northern clubshell). Michigan Natural Features Inventory, Lansing, MI. 4pp.
  • Badra, P.J. and R.R. Goforth. 2002. Surveys of Native Freshwater Mussels in the Lower Reaches of Great Lakes Tributary Rivers in Michigan. Report number MNFI 2002-03. Report to Michigan Department Of Environmental Quality, Coastal Zone Management Unit, Lansing, MI. 39pp.
  • Box, J.B. and J. Mossa. 1999. Sediment, land use, and freshwater mussels: prospects and problems. Journal of the North American Benthological Society 18:99-117.
  • Burch, J.B. 1994. Mollusk: Species Accounts. Pages 395-410 in D.C. Evers, ed. Endangered and Threatened Wildlife of Michigan. University of Michigan Press, Ann Arbor.
  • 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.
  • Evers, D.C. 1994. Endangered and Threatened Wildlife of Michigan. The University of Michigan Press, Ann Arbor. 412pp.

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