Percina tanasiSnail Darter
Geographic Range
Once limited to the Tennessee River and tributaries, the darter now also lives in connected reservoirs. In 1975 and 1976, a population was transplanted to the Hiwassee River, and is doing well.
Habitat
Moderately flowing, vegetated streams with sandy bottoms and wide shoals for spawning.
- Aquatic Biomes
- rivers and streams
Physical Description
- Other Physical Features
- bilateral symmetry
Reproduction
Between January and mid-March, adult snail darters spawn on river shoals. Eggs deposited in gravel or on rocks hatch in 15 to 20 days.
Lifespan/Longevity
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- Average lifespan
Status: captivity - 4 years
- AnAge
- Average lifespan
Behavior
Newly hatched snail darters drift downstream, later returning to the shoal areas. They are short-lived, with a maximum age of five or six years.
- Key Behaviors
- natatorial
- motile
Communication and Perception
Food Habits
The snail darter eats small invertebrates, with aquatic snails making up about 60 percent of the darter's food, with some variation among seasons.
Economic Importance for Humans: Positive
By traditional economics, the snail darter has no significant positive economic importance. However, when listed as an Endangered Species in 1975, it was the focus of a Supreme Court case that set the precedent for protecting endangered species, regardless of cost.
Economic Importance for Humans: Negative
The snail darter case caused the Tellico Dam project to be halted. In response, Congress amended the Endangered Species Act to include a "God Squad", which could overrule protecting a species under enormous economic sacrifice. The committee got its name because it can play "God" and allow species to go extinct for economic reasons.
Conservation Status
Originally classified as Endangered on October 9, 1975. Reclassified as Threatened on July 5, 1984. A number of new populations have been found, increasing the number of known individuals.
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- IUCN Red List
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Vulnerable
More information
Other Comments
The snail darter has become a symbol for conservationists and anti-environmentalists alike. Eventually, an act was passed by Congress requiring completion of the Tellico Dam. The act went on record as being the first offical U.S. government decision to extirpate a species. Only because of a successful transplant by the Fish and Wildlife Service does the snail darter still exist. The animal is a reminder of the relative importance of conserving biodiversity compared to development in the eyes of the United States government.
Contributors
Noah Hall (author), University of Michigan-Ann Arbor.
Glossary
- Nearctic
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living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- chemical
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uses smells or other chemicals to communicate
- motile
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having the capacity to move from one place to another.
- natatorial
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specialized for swimming
- native range
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the area in which the animal is naturally found, the region in which it is endemic.
- tactile
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uses touch to communicate
References
Lowe, David W., John R. Matthews. and Charles J. Moseley. The Official WWF Guide to Endangered Species of North America. Volume 2. Washington, D.C.: Beacham Publishing, Inc., 1990. 921- 923.