Speoplatyrhinus

The Alabama cavefish (Speoplatyrhinus poulsoni), is a critically endangered species of amblyopsid cavefish found only in underground pools in Key Cave, located in northwestern Alabama, United States in the Key Cave National Wildlife Refuge. It was discovered underneath a colony of gray bats in 1967 and scientifically described in 1974. On any single visit to the cave, no more than 10 individuals of this fish have been observed, and scientists estimate fewer than 100 are left. This fish is believed to be the rarest species of cavefish in the United States and one of the rarest of all freshwater fish. It exists in a fragile ecosystem based on nutrient-rich guano of the gray bat. Researchers have failed to find the fish in any other location. The Alabama cavefish is one of the rarest cavefish species in North America. This species was discovered in 1967 by researcher John E. Cooper, and several specimens were observed over subsequent years. It was so unusual that he and co-author Robert A. Kuehne created a new genus for its description. The species is restricted to Key Cave in Lauderdale County, Alabama, with only 9 specimens having been collected (all before 1983). Because the underground water system in the area is so widespread, it was hoped that the cavefish had dispersed to other sites. However, studies of 120 other caves in the area, conducted since 1977, have failed to locate any other cavefish populations. No more than 10 individuals have been observed on any single visit to the Key Cave and in 36 visits from 1967 to 1998, the average was less than 4 per visit. The total number of individuals in the Key Cave population is estimated to be less than 100. Initially classified as vulnerable by the IUCN, its status has been gradually upgraded as its extreme rarity became apparent. It is currently considered critically endangered. Two reports of these fish in nearby Collier Cave are unconfirmed. Both caves are protected and inaccessible to the public. It is estimated that its longevity ranges from 5 to 10 years. Because its known range is limited to a single cave, the Alabama cavefish has an uncertain future, being threatened by changes in groundwater quality and level, changes in aquifer characteristics, and diminished organic input. It also may compete with the syntopic southern cavefish (Typhlichthys subterraneus), which is more abundant and aggressive. Cave crayfish sometimes feed on Alabama cavefish. The Alabama cavefish is up to 7.2 cm (2.8 in) long and has no eyes or discernible pigmentation, appearing semitransparent with a slight pink hue. Its large head makes up more than one-third of its length. It is the only species in its genus, and can be distinguished from other cavefish with its very elongated, flattened head with a laterally constricted snout and a terminal mouth. The cavefish lacks pelvic fins, and its fin rays are unbranched with the fin membranes deeply incised between the rays. It has an elaborate system of sensory papillae, arranged in ridges on the head and sides, an adaptation to the dark environment. Its diet of copepods, isopods, amphipods, and smaller cavefish is supported by the nutrient-filled bat guano. It can also survive on other small organisms such as mites, spiders, millipedes, and beetles and other insects. It may reproduce like northern cavefish, by carrying its young inside its mouth to be incubated. Since its reproductive cycle appears to be based on various environmental triggers, it does not reproduce every year. Its reproduction could be caused by seasonal flooding in the cave, which causes hormonal changes in the species.