The shiny pigtoe (Fusconaia cor) is a freshwater mussel native to the southeastern United States. An individual pigtoe grows to around 2 inches in length and lives in a smooth, yellow-brown shell. The shiny pigtoe is a filter feeder, highly sensitive to pollution and industrial runoff. Cumulative degradation of water quality has decimated shiny pigtoe populations; the species is critically endangered as a result.
Historically, the shiny pigtoe was common in the Tennessee River and at least 10 of its tributaries that flowed through Tennessee, Virginia and Alabama. Today the species occurs in isolated populations across approximately 20 percent of the creature's historic range. Populations can be found in the Clinch and Powell rivers of Virginia and Tennessee, Virginia's North Fork Holston River, Tennessee's Elk River and the Paint Rock River in Alabama.
Shiny pigtoes require fast-flowing, shallow streams and rivers with stable sand or gravel substrate where they can bury themselves. They've never lived in deep water and disappear from reservoirs and lakes that result when a river is dammed. The rivers of their historic range have been exploited for industry and have become polluted by chemical waste and runoff from strip-mining, making the water unsuitable for shiny pigtoes. The mussels have also lost habitat to invasive species such as the Asian clam and the zebra mussel, which outcompete shiny pigtoes for resources.
Reproduction and Development
Shiny pigtoes reproduce similarly to other freshwater mussels. The males release sperm into the water column, and the females absorb it as they breathe and feed. They then retain the fertilized eggs in their gills and release them into the water column when they've become larvae. The larvae attach themselves to host fish, such as whitetail and common shiners, until they've developed into juveniles. Because they depend on these host fish, the survival of the species depends on the health and distribution of host fish populations.
The U.S. federal government listed the shiny pigtoe species as endangered in 1976, and the Fish & Wildlife Service created and implemented a recovery plan for the species in 1984. Experimental populations have been cultivated to adulthood in controlled environments and then introduced into rivers in the shiny pigtoe's historic range. Many of the rivers in the species' historic range are no longer suitable for re-establishing populations as a result of dam construction and water pollution. A shiny pigtoe population living in the portion of the Clinch River around Pendleton Island is part of a nature preserve maintained by the Nature Conservancy, but this is the only population living in a protected area.
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