Endangered Species
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Rough Pigtoe (Pleurobema plenum)


photo of rough pigtoe mussel


The fish hosts for this mussel's parasitic larvae are thought to include rosefin shiners and bluegills.


Status: Endangered


Habitat: This mussel is found in a wide variety of streams from large to small. It buries itself in bottoms of firmly packed sand or gravel with its feeding siphons exposed.


Behavior: Reproduction requires a stable, undisturbed habitat and a sufficient population of host fish 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 larvae that manage to attach themselves to the gills of a host fish by means of tiny clasping valves, grow into juveniles with shells of their own. At that point they detach from the host fish and settle into the streambed, ready for a long (possibly up to 50 years) life as an adult mussel.


Why It's Endangered: Reasons for this mussel's decline are not fully known, but throughout all the drainages from which it is now absent, habitat has been severely altered or destroyed. Impacts include dams for power and navigation, siltation from agricultural run-off, chemical pollution from agricultural pesticides and industrial wastes, and effluent from strip-mining and coal-washing operations.


An added threat is now the zebra mussel, a fast-spreading exotic (non-native) species from the Caspian Sea area. These tiny mussels reproduce in enormous numbers which tend to cover and suffocate native mussels. They also often outcompete native mussels for food.


Back to Freshwater Mussels




Last updated: October 10, 2018