The Alabama cave shrimp, Palaemonias alabamae, is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of shrimp

Shrimp

Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...

 in the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Atyidae

Atyidae

Atyidae is a family of shrimp, present in all tropical and most temperate waters of the world. Adults of this family are almost always confined to fresh water...

, found only in caves in the state of 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...

.

Conservation status

Palaemonias alabamae is listed as an endangered species

Endangered species

An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 both 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 since September 7, 1988 under the U.S. 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...

.

Distribution

The Alabama cave shrimp is only known from five cave

Cave

A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...

s, all in Madison County

Madison County, Alabama

Madison County is a county of the U.S. state of Alabama, and is a major part of the Huntsville Metropolitan Area.It is also included in the merged Huntsville-Decatur Combined Statistical Area. The county is named in honor of James Madison, fourth President of the United States of America, and the...

, 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...

. Shelta Cave

Shelta Cave

Shelta Cave is a long underground cave and lake located in Huntsville, Madison County, Alabama. It is described as one of the most biodiverse caves within the Appalachian Mountains. The cave is currently owned and managed as a nature preserve by the National Speleological Society, with their main...

 is the species' type locality, but viable populations have only been confirmed in Bobcat Cave and the complex comprising Hering Cave, Glover Cave and Brazelton Cave.

Ecology

P. alabamae occurs in cave pools with silt

Silt

Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...

y bottoms. Predators of the Alabama cave shrimp include the southern cavefish Typhlichthys subterraneus

Typhlichthys subterraneus

Typhlichthys subterraneus is a species of fish in the Amblyopsidae family. It is endemic to karst regions of the eastern United States.-Taxonomy:...

, the Tennessee cave salamander

Tennessee Cave Salamander

The Tennessee Cave Salamander is a species of salamander in the Plethodontidae family.It is endemic to the United States.Its natural habitats are inland karsts and caves.It is threatened by habitat loss.-References:...

 Gyrinophilus palleucus, various crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 species, bullfrog

Bullfrog

The American bullfrog , often simply known as the bullfrog in Canada and the United States, is an aquatic frog, a member of the family Ranidae, or “true frogs”, native to much of North America. This is a frog of larger, permanent water bodies, swamps, ponds, and lakes, where it is usually found...

s and raccoon

Raccoon

Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...

s.

Taxonomy

The closest relative of the Alabama cave shrimp is the Kentucky cave shrimp

Kentucky cave shrimp

The Kentucky cave shrimp, Palaemonias ganteri, is an eyeless, troglobite shrimp. It lives in caves in Barren County, Edmonson County, Hart County and Warren County, Kentucky...

, Palaemonias ganteri, which lives in Mammoth Cave National Park

Mammoth Cave National Park

Mammoth Cave National Park is a U.S. National Park in central Kentucky, encompassing portions of Mammoth Cave, the longest cave system known in the world. The official name of the system is the Mammoth-Flint Ridge Cave System for the ridge under which the cave has formed. The park was established...

, Kentucky

Kentucky

The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...

. The two species can be distinguished by size (P. alabamae being larger than P. ganteri), the longer rostrum

Rostrum (anatomy)

The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....

in P. alabmae, and the greater number of spines on the rostrum of P. alabamae.