Caecidotea nickajackensis
Encyclopedia
Caecidotea nickajackensis is a species of isopod
Isopoda
Isopods are an order of peracarid crustaceans, including familiar animals such as woodlice and pill bugs. The name Isopoda derives from the Greek roots and...

 crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

 in the family Asellidae
Asellidae
Asellidae is a family of isopod crustaceans. It is one of the largest families of freshwater isopods, living in both epigean and hypogean habitats in North America and Europe...

. It was endemic to a single cave in Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

, and is thought to have been exterminated when that cave was flooded in 1967 by the building of the Nickajack Dam
Nickajack Dam
Nickajack Dam is a hydroelectric dam in Marion County in the U.S. state of Tennessee. It is one of nine dams on the Tennessee River owned and operated by the Tennessee Valley Authority, which built the dam in the mid-1960s to replace the outdated Hales Bar Dam upstream. The dam impounds the ...

.

Distribution

Caecidotea nickajackensis is only known to have occurred in Nickajack Cave
Nickajack Cave
Nickajack Cave is a large, partially flooded cave in Marion County, Tennessee. It was partially flooded by the Tennessee Valley Authority's Nickajack Lake, created by the construction of Nickajack Dam in 1967. The entrance was originally 140 feet wide and 50 feet high...

, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

, before the building of the Nickajack Dam
Nickajack Dam
Nickajack Dam is a hydroelectric dam in Marion County in the U.S. state of Tennessee. It is one of nine dams on the Tennessee River owned and operated by the Tennessee Valley Authority, which built the dam in the mid-1960s to replace the outdated Hales Bar Dam upstream. The dam impounds the ...

 by the Tennessee Valley Authority
Tennessee Valley Authority
The Tennessee Valley Authority is a federally owned corporation in the United States created by congressional charter in May 1933 to provide navigation, flood control, electricity generation, fertilizer manufacturing, and economic development in the Tennessee Valley, a region particularly affected...

 in 1967. Two other obligate stygobionts were exterminated in the same action – the pseudoscorpion
Pseudoscorpion
A pseudoscorpion, , is an arachnid belonging to the order Pseudoscorpionida, also known as Pseudoscorpiones or Chelonethida....

 Microcreagris nickajackensis and the ground beetle
Ground beetle
Ground beetles are a large, cosmopolitan family of beetles, Carabidae, with more than 40,000 species worldwide, approximately 2,000 of which are found in North America and 2,700 in Europe.-Description and ecology:...

 Pseudanophthalmus nickajackensis.

Conservation

C. nickajackensis is listed as a vulnerable species
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...

 on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

, and as a "species of concern" under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

. It was extirpated from Nickajack Cave in 1967, and is now thought to be extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

.

Taxonomy

Caecidotea nickajackensis was first described by Alpheus Spring Packard
Alpheus Spring Packard
Alpheus Spring Packard, LL.D. was an American entomologist and palaeontologist. He was the son of Alpheus Spring Packard, Sr. and the brother of William Alfred Packard. He was born in Brunswick, Maine and was Professor of Zoology and Geology at Brown University in Providence, Rhode Island from...

, in an 1881 publication by Edward Drinker Cope
Edward Drinker Cope
Edward Drinker Cope was an American paleontologist and comparative anatomist, as well as a noted herpetologist and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested in science; he published his first scientific paper at the age of nineteen...

 and himself, titled The Fauna of Nickajack Cave. A second species, C. richardsonae, was described from the same cave by William Perry Hay
William Perry Hay
William Perry Hay was an American zoologist known for work on crayfish and reptiles. He was the son of Oliver Perry Hay.- References :...

 in 1901, and was thought to be a junior synonym of C. nickajackensis for a long time. It is now recognised as a separate species distributed from Alabama
Alabama
Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

 to Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

.
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