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The bright purple interior of two purple cat’s paw mussels on a leaf strewn bank
Information icon Purple cat’s paw mussels. Photo by USFWS.

Purple cat’s paw

Epioblasma obliquata obliquata

The Purple cat’s paw (Epioblasma obliquata obliquata) is one of the rarest freshwater mussels and was considered to be on the brink of extinction. It was listed as endangered in 1990 when some live adults were found but were too old to reproduce. In 1994, surveyors found a reproducing population in Killbuck Creek, Ohio. Currently more studies are needed to determine whether any additional populations of this species survive and to also monitor the known populations. More research also needs to be done into the life history.

Appearance

Purple cat’s paws are medium-sized mussels that are roughly rectangular. The outside surface had distinct growth lines, fine wavy green rays, smooth and shiny surface and is a yellowish-green, yellow or brownish color. The inside of the shell is a lustrous purple to deep purple.

The bright purple interior of the purple cats paw mussel on display sitting in shallow water
Purple cat’s paw mussels. Photo by Angie Boyer, USFWS.

Habitat

The purple cat’s paw inhabits large rivers with sandy gravel substrates. It occurs in water of shallow to moderate depth with a swift current.

Diet

Purple cat’s paw mussels are filter-feeders. They feed on organic detritus, phytoplankton, and tiny zooplankton.

Historic range

Alabama, Illinois, Indiana, Kentucky, Ohio, and Tennessee.

Current range

A small breeding population was located in Killbuck Creek, Ohio, in 1994. Currently the purple cat’s paw that have been released after captive propagation have been released back to Killbuck Creek until other sites are deemed suitable.

Conservation challenges

Similar to many other freshwater mussels, conservation challenges are due to industrial and agricultural developments which result in environmental changes. Mussels are a known water quality indicator and are fairly sensitive to major changes. Construction of dams can not only cause isolation of populations by blocking host fish migration routes, but also cause changes in water temperature, especially around the base of the dam. This causes colder water, which alters mussels’ natural biological timers.

A biologist's hand holding a half dozen medium-sized mussels with bright orange identifying numbers
Purple cat’s paws mussels, tagged and ready to be placed in Killbuck Creek, Ohio. Photo by USFWS.

Siltation caused by activities such as logging and mining increases the amount of sediment flowing in river systems, burying the mussels and eventually leading to suffocation. Mussels, particularly juveniles or small adult mussels, aren’t able to dig themselves out.

Another challenge comes from water pollution, either agricultural runoff or industrial pollution. Although mussels do filter out river systems to help rid it of pollutants, excess amounts of toxins will result in death. Pollutants that contribute to algal blooms are also detrimental as they can use up more oxygen and prevent water flow.

Recovery plan

Download the 1992 recovery plan.

Partnerships, research and projects

The Kentucky Department of Fish and Wildlife Resources Center for Mollusk Conservation culture the purple cat’s paw at their facility in Frankfort, Kentucky. Once they have grown for a few weeks they are brought to Wolf Creek National Fish Hatchery, where they are placed into cages built specifically for mussel propagation. These cages are placed in floating racks in Lake Cumberland where they will reside for one to two growing seasons, from April to October. Staff at Wolf Creek monitor cages weekly, brushing off excess algae to allow optimal food flow through. Once the juveniles have been deemed big enough they are released back to their natural habitat.

How you can help

  • Protect waterways, keep clean of garbage and other liquid pollutants.
  • Volunteer time to various organizations aimed at habitat restoration projects, i.e Kentucky Wild programs.

Subject matter experts

  • Kentucky Department of Fish & Wildlife Center for Mollusk Conservation

Federal Register notices

The following Federal Register documents were automatically gathered by searching the Federal Register Official API with this species’ scientific name ordered by relevance. You can conduct your own search on the Federal Register website.

  • We're sorry but an error occurred. Visit the Federal Register to conduct your own search.

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