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