Crayfish, Hell Creek Cave

Cambarus zophonastes

phylum: Arthropoda

class: Crustacea

order: Decapoda

family: Cambaridae

status: Critically endangered, IUCN Endangered, ESA

range: USA (Arkansas)

Description and biology

The Hell Creek Cave crayfish is colorless. It has small eyes that lack any pigment (color) and a spined rostrum (snout). An average adult measures 2.6 inches (6.6 centimeters) long. Like other crayfish, it feeds on both plants and animals, including algae, snails, insects, worms, and mussels.

Although appearing similar to lobsters (their salt water cousins), crayfish have a different life cycle. They do not pass through any larval stages, but go directly from an egg to a miniature adult form. Hell Creek Cave crayfish reproduce very slowly. Biologists (people specializing in the study of living organisms) believe they lay eggs once every five years, on average. As in other crayfish species, the female Hell Creek Cave crayfish shelters her fertilized eggs by carrying them attached to her abdomen. After the eggs hatch, the young crayfish cling to that spot on the mother's body for several weeks before letting go.

Crayfish are preyed on by bass, sunfish, raccoons, otters, herons, and kingfishers.

Habitat and current distribution

The Hell Creek Cave crayfish is found only in a deep pool in Hell Creek Cave, which is located in the Ozark Mountains in Stone County, Arkansas. Surveys conducted in the mid- 1980s recorded less than 50 crayfish at this site and the population has remained near that figure into the 2000s.

Hell Creek Cave is mostly wet and muddy throughout the year. Many of its passages are flooded during the rainy seasons and after storms. A narrow, shallow stream leads to the pool inhabited by the crayfish. The pool is approximately 150 feet (46 meters) away from the cave entrance.

History and conservation measures

There are about 330 known species of crayfish, which are also known as crawfish or crawdads. Although nearly half of those species are endangered or imperiled, only four species have been placed on the U.S. Endangered Species List. The Hell Creek Cave crayfish is one of those four.

This species of crayfish faces a number of threats. A surface stream supplies water to the cave's pool. This stream can easily become polluted with wastes from nearly industries. Once polluted, the stream will in turn contaminate the pool, destroying the crayfish's fragile habitat.

Biologists believe the Hell Creek Cave crayfish reproduces so slowly because it does not get enough nourishment. The cave has a shortage of organic matter for the crayfish to use as energy. In the past, most of this organic matter came from the guano (feces) of gray bats (Myotis grisescens). However, the gray bat is now an endangered species. It has disappeared from Hell Creek Cave as well as from many other caves.

Finally, the Hell Creek Cave crayfish is threatened by human collectors who venture into the cave to capture specimens. The removal of any adult crayfish, especially reproducing females, can have a dramatic effect on the future population of the species.

A tract of land that includes the entrance to Hell Creek Cave has recently been placed under protection. This act should limit the number of humans entering the cave and disturbing its ecosystem (an ecological system including all of its living things and their environment). Conservationists (people protecting the natural world) hope it will also allow gray bats to return to the cave, which will greatly benefit the Hell Creek Cave crayfish.