Plants and Animals

Ptychobranchus fasciolaris Kidney shell

Key Characteristics

The kidney shell is a medium to large (to 6 inches), elongate, and heavy mussel with a low and wide beak, straight to moderately curved ventral margin and well developed teeth. Shell is typically light in color, ranging from yellowish-tan to light brown, often with thick, broken green rays.  There is often a wrinkle on the inside surface of the shell.

Status and Rank

US Status: No Status/Not Listed
State Status: SC - Special Concern (rare or uncertain; not legally protected)
Global Rank: G4G5 - Rank is uncertain, ranging from apparently secure to secure
State Rank: S2 - Imperiled


CountyNumber of OccurrencesYear Last Observed
Alpena 2 1971
Barry 1 2010
Berrien 1 Historical
Branch 1 1927
Cheboygan 2 2018
Clinton 1 2010
Gladwin 2 2020
Gratiot 5 2020
Hillsdale 2 2019
Isabella 1 2020
Lenawee 1 1931
Livingston 8 2019
Macomb 12 2017
Midland 4 2020
Monroe 3 2018
Montcalm 1 2015
Oakland 6 2020
Saginaw 8 2011
Sanilac 2 2010
Shiawassee 2 1937
St. Clair 12 2020
Tuscola 4 2004
Washtenaw 10 2020
Wayne 23 2019

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 kidney shell occurs in high water quality creeks, rivers and lakes with moderate to swift currents and a sand or gravel substrate (Watters et al. 2009).

Natural Community Types

  • Great lake, littoral, benthic
  • Great lake, pelagic, benthic
  • Inland lake, littoral, benthic
  • Inland lake, pelagic, benthic
  • Mainstem stream (3rd-4th order), pool
  • Mainstem stream (3rd-4th order), run
  • Mainstem stream (3rd-4th order), riffle
  • 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

The kidney shell experiences an especially high mortality rate in low dissolved oxygen conditions (Teztloff 2001). Limiting agricultural and urban runoff, wastewater treatment discharge, and other sources of point and non-point source pollution which contribute to such conditions will benefit this species. As zebra mussel infestation has lead to the extirpation of many native mussel communities, boat hulls and trailers, fishing gear and scuba equipment should be thoroughly cleaned before moving between waterbodies, in order to prevent the spread of zebra mussel larvae and adults. Construction projects such as bridge replacements and dam removals should plan for monitoring and mitigation measures to limit the impacts on mussel poplutions. A number of different fish species serve as hosts to Kidney shell glochidia. Healthy populations of host fish, as well as open water systems that allow for their movement,  must be maintained.

Active Period

Gravid from first week of August to fourth week of May

Survey Methods

Visual and tactile search using scuba or glass-bottom buckets. Tactile search (by hand) is especially important where water turbidity and pebbles/rocks make visual detection difficult. After identification, live mussels should be planted back into the substrate anterior end down. Surveys should not take place after heavy rains or during periods of high water as these conditions can make detection much more difficult. Methods of documenting survey effort include: searching a large measured area, e.g. 128m2; taking multiple quadrat samples; and recording search time (person hours). For all methods, at least some excavation of substrate (by hand, 5-10cm down) should be done to detect buried mussels. Searching a large measured area or timed searches are generally better for detecting rare species and generating a species list than quadrat sampling. These two methods allow more types of microhabitats and a larger area to be covered. Quadrat sampling is better suited for documenting changes in density and other statistical analyses at the site level (Strayer and Smith 2003).

Glass-bottom bucket less than waist deep water

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

Time of Day: Daytime
Water Level: Low Water Levels
Water Turbidity: Low Turbidity

SCUBA greater than waist deep water

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

Time of Day: Daytime


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.

Technical References

  • Bogan, A.E. 1993. Freshwater Bivalve Extinctions (Mollusca: Unionida): A Search for Causes.
  • Bringolf, R.B., W.G. Cope, C.B. Eads, P.R. Lazaro, M.C. Barnhart, and D. Shea. 2007. Acute and chronic toxicity of technical-grade pesticides to glochidia and juveniles of freshwater mussels (Unionidae). Environmental Toxicology and Chemistry 26(10):2086-2093.
  • Grabarkiewicz, J. and W. Davis. 2008. An introduction to freshwater mussels as biological indicators. EPA-260-R-08-015. U.S. Environmental Protection Agency, Office of Environmental Information, Washington, DC.
  • Minnesota Pollution Control Agency. 2009. Low Dissolved Oxygen in Water: Causes, Impact on Aquatic Life - An Overview. Water Quality/Impaired Waters 3.24.
  • Sethi, Suresh A., Andrew R. Selle, Martin W. Doyle, Emily H. Stanley, and Helen E. Kitchel. 2004. Response of unionid mussels to dam removal in Koshkonong Creek, Wisconsin (USA). Hydrobiologia 525:157-165.
  • Strayer, D.L. and D.R. Smith. 2003. A Guide to Sampling Freshwater Mussel Populations. American Fisheries Society Monograph 8, Bethesda. 103pp.
  • Teztloff, J. 2001. Survival Rates of Unionid Species Following a Low Oxygen Event in Big Darby Creek, Ohio. Ellipsaria 3(3):18-19.
  • Watters, G. Thomas, Michael A. Hoggarth, and David H. Stansbery. 2009. The Freshwater Mussels of Ohio. The Ohio State University Press, Columbus. 421 pp.