FWS Focus

Overview

Characteristics
Overview

The purple cat's paw pearlymussel is one of our rarest freshwater mussels and it was truly on the brink of extinction when listed in 1990. At the time of listing, a few live adults could be found but they were too old to reproduce. We thought that the species was functionally extinct. In 1994, surveyors found a reproducing population in Killbuck Creek, Ohio. Since that time, successful captive propagation efforts have lead to multiple reintroductions of the species into streams where it historically occurred.

Scientific Name

Epioblasma obliquata obliquata
Common Name
purple cat's paw pearly mussel
catspaw
Purple Cat's paw (=Purple Cat's paw pearlymussel)
FWS Category
Clams
Kingdom

Location in Taxonomic Tree

Identification Numbers

TSN:

Characteristics

Characteristic category

Habitat

Characteristics
Habitat

This mussel lives in medium to large rivers of the Ohio River Basin. It prefers shallow water and requires a swift current to avoid being buried in silt. It is found on bottom substrates ranging from sand to boulders.

River or Stream

A natural body of running water.

Characteristic category

Food

Characteristics
Food

This mussel lives in medium to large rivers of the Ohio River Basin. It prefers shallow water and requires a swift current to avoid being buried in silt. It is found on substrates ranging from sand to boulders.

Characteristic category

Physical Characteristics

Characteristics
Physical Characteristics

Purple cat’s paw pearlymussels spend most of their life in a small area of the stream bed. They are typically completely or partially buried in the substrate.  They are relatively sedentary, though they do have the ability to move around with the use of their muscular foot.  Mussels insert their "foot" into the sand or gravel and pull themselves forward, inching their way along the bottom.

Size & Shape

The purple cat’s paw pearlymussel has a medium-sized shell that is squarish with rounded edges. The species is sexually dimorphic, meaning males and females differ in appearance. The shell of the male has a narrow, shallow central depression or groove and the edge of the female's shell extends outward at one end. Males can grow to 70 mm with females being considerably smaller.

Color & Pattern

The shell’s outside surface has numerous distinct growth lines. It is yellowish-green, yellow, or brownish in color and has fine, faint, wavy green rays with a smooth and shiny surface. The shells of the young often have a satin-like surface. The inside of the shell is purplish to deep purple.

Characteristic category

Life Cycle

Characteristics
Life Span

The purple cat’s paw may live up to 25 years. They reach sexual maturity at around age 3.

Reproduction

Reproduction requires a stable, undisturbed habitat and a sufficient population of fish hosts to complete the mussel's larval development. When the male discharges sperm into the current, females downstream siphon in the sperm in order to fertilize their eggs, which they store in their gill pouches until the larvae hatch. The females then expel the larvae. Those that manage to attach themselves to the gills of a host fish grow into juveniles with shells of their own. At that point they detach from the host fish and settle into the streambed, ready for life as an adult mussel.

Life Cycle

The purple cat’s paw pearly mussel has a complicated life history that is tightly linked to freshwater fishes. Fertilized eggs develop into larvae, called glochidia, in the female mussels. Glochidia, when released from the female, must come in contact with a passing fish and attach to the gills, fins, or body of that fish. During this parasitic stage, the mussel glochidia are relatively harmless to their fish host. Purple cat’s paws are "host specific" in that their glochidia can only survive on a specific species of fish. If a glochidium attaches to a fish that is not a suitable host species, it will not survive. After several weeks, the glochidia free themselves from the host, drift to the substrate and begin their lives as juvenile mussels. The mussel-host fish relationship helps disperse a basically immobile creature (the mussel), within and between bodies of water.

Characteristic category

Behavior

Characteristics
Behavior

The purple cat’s paw pearly mussel feeds by using a siphon to filter small organic particles, such as bacteria, algae, and detritus, out of the water column.

Geography

Characteristics
Range

The purple cat’s paw pearlymussel was historically distributed in the Ohio, Cumberland, and Tennessee River systems in Ohio, Illinois, Indiana, Kentucky, Tennessee, and Alabama.  Currently, the subspecies occurs in the Ohio River and four of its tributaries (Killbuck Creek (OH), Walhonding River (OH), Green River (KY), Licking River (KY)) and one Tennessee River tributary (Duck River (TN)). With the exception of the Killbuck Creek population, all of these populations were reintroduced into these streams in 2017. 

Launch Interactive Map

Timeline

Explore the information available for this taxon's timeline. You can select an event on the timeline to view more information, or cycle through the content available in the carousel below.

12 Items

Listing

Listing

Experimental Pop Designation (10j)

Experimental Pop Designation (10j)

Experimental Pop Designation (10j)

Experimental Pop Designation (10j)

Experimental Pop Designation (10j)

Correction

Five Year Review

Five Year Review

Five Year Review

Technical Correction

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Listing

Jul 27, 1989

Jul 27, 1989 Listing (Endangered)
ETWP; Proposal to List Purple Cat's Paw Pearly Mussel as an Endangered Species; 54 FR 31209 312…
  • Publication type: Proposed
Item 1

Listing

Jul 10, 1990

Jul 10, 1990 Listing (Endangered)
ETWP; Purple Cat's Paw Pearly mussel Determined to be an Endangered Species; 55 FR 28209 28213
  • Publication type: Final
Item 2

Experimental Pop Designation (10j)

May 27, 1999

May 27, 1999 Experimental Pop Designation (10j) (Non-essential)
ETWP; Proposed Establishment of Nonessential Experimental Population Status for Sixteen Freshwater M…
  • Publication type: Proposed
Item 3

Experimental Pop Designation (10j)

May 27, 1999

May 27, 1999 Experimental Pop Designation (10j) (Non-essential)
ETWP; Proposed Establishment of Nonessential Experimental Population Status for Sixteen Freshwater M…
  • Publication type: Final
Item 4

Experimental Pop Designation (10j)

May 27, 1999

May 27, 1999 Experimental Pop Designation (10j) (Non-essential)
ETWP; Proposed Establishment of Nonessential Experimental Population Status for Sixteen Freshwater M…
  • Publication type: Proposed
Item 5

Experimental Pop Designation (10j)

Jun 14, 2001

Jun 14, 2001 Experimental Pop Designation (10j) (Non-essential)
ETWP; Establishment of Nonessential Experimental Population Status for 16 Freshwater Mussels and 1…
  • Publication type: Final
Item 6

Experimental Pop Designation (10j)

Jun 14, 2001

Jun 14, 2001 Experimental Pop Designation (10j) (Non-essential)
ETWP; Establishment of Nonessential Experimental Population Status for 16 Freshwater Mussels and 1…
  • Publication type: Final
Item 7

Correction

Aug 21, 2001

Aug 21, 2001 Correction
ETWP; Establishment of Nonessential Experimental Population Status for 16 Freshwater Mussels and 1…
  • Publication type: Notice
Item 8

Five Year Review

Mar 18, 2009

Mar 18, 2009 Five Year Review (Information Solicitation)
Notice of initiation of review; request for information on nine listed Midwestern species
  • Publication type: Notice
Item 9

Five Year Review

Jul 8, 2014

Jul 8, 2014 Five Year Review (Information Solicitation)
Initiation of 5-Year Status Reviews of Nine Listed Animal and Two Listed Plant Species
  • Publication type: Notice
Item 10

Five Year Review

Apr 26, 2019

Apr 26, 2019 Five Year Review (Information Solicitation)
Initiation of 5- Year Status Reviews of Six Listed Animal and Plant Species; request for information
  • Publication type: Notice
Item 11

Technical Correction

Mar 17, 2022

Mar 17, 2022 Technical Correction
Endangered and Threatened Wildlife and Plants;
  • Publication type: Direct Final
Item 12