Epioblasma obliquata perobliqua
White catspaw

Key Characteristics

The white catspaw is a medium sized mussel (to 2 inches) with a thick shell and a heavy hinge with distinct teeth. Ridges are often present along the growth lines on the posterior of the shell. There is considerable sexual dimorphism in this species. The shell of the male is oval and elongate with a shallow sulcus whereas the female has a rectangular or quadrate shell with a deep sulcus. The shell is tan with many wavy green rays and the nacre color is white.

Status and Rank

  • State Status: E
  • US Status: LE
  • State Rank: SH
  • Global Rank: G1T1


County NameNumber of OccurrencesYear Last Observed
Distribution map for Epioblasma obliquata perobliqua

Updated 5/15/2018. 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.


Because the White catspaw is so rare, little is known of their required habitat. In Fish Creek where the only extant population exists, the species has been found in riffles or runs of high gradient streams. Coarse, stable substrates, such as gravel and pebble, are preferred. While the species has been found on the surface of the substrate (Clark 1977), the lack of marl or algae on freshly dead shells indicates that the white catspaw is typically buried in the substrate (USFWS1990). In Michigan, the White catspaw also has been collected in large rivers, such as the Detroit River, and in the nearshore areas of Lake Erie.

Specific Habitat Needs

Gravel, pebble substrate needed in Headwater Stream (1st-2nd order), Riffle, Headwater Stream (1st-2nd order), Run

Natural Community Types


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.


Maintain high water quality and protect the host fish fauna. Like all filter-feeding mussels, the white catspaw is sensitive to siltation, and efforts should be made to decrease surface run-off. Changes in river hydrology and morphology can also harm this riffle-dwelling species, and dredging, channelization and damming projects should be avoided. Maintenance or establishment of vegetated riparian buffers can help protect mussel habitats from many of their threats. Control of zebra mussels is critical to preserving native mussels. And as with all mussels, protection of their hosts habitat is also crucial.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed Sep 23, 2018]

More Information

See MNFI Species Abstract


Survey References

Technical References

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