Speoplatyrhinus poulsoni
Alabama cavefish

Speoplatyrhinus poulsoni is a cavefish whose range is limited solely to Key Cave, Lauderdale County, Alabama, north of the Tennessee River. (Kuhajda and Mayden, 2001)

Key cave, the single locale of S. poulsoni, is a large underground multi-level structure that has thousands of meters of mapped area. The pools of water in the cave in which the fish dwell are typically 5 to 10 feet deep. Seasonal flooding within the cave fluctuates this depth. Far within the cave are very deep pools of unknown depth. However no evidence exists that S. poulsoni can be found in these deep pools. Above the pools are bat roosts which, via guano droppings, supply the pools with nutrients and have established small, flourishing ecosystems. The water in the pools is groundwater with a constant temperature of about 16 C and dissolved oxygen concentrations between 7 and 9.8 ppm. The pools receive no natural light. (Kuhajda and Mayden, 2001; Romero, 1998)

Speoplatyrhinus poulsoni is a troglobitic fish of the family Amblyopsidae. They have no eyes and almost no pigment, making them nearly transparent. On average members of this species have a length close to 50 mm, ranging from 30-58 mm. They have an elongated, flattened head with a laterally constricted snout and a terminal mouth. Speoplatyrhinus poulsoni has no pelvic fins, a relatively high dorsal fin that mirrors the anal fin in size and shape, and a rounded paddle-shaped homocercal tail. Embedded cycloid scales cover the body and bifurcate fin rays are absent in all fins. Alabama cavefish have an elaborate system of sensory papillae on the sides and head and a hypertrophied lateral-line. The major distinguishing feature between it, and the only other cavefish in Alabama, Typhlichthys subterraneus, are the three nonpapilliferous fin rays between the medial-most rows of caudal sensory papillae (whereas T. subterraneus has 5). (Romero, 1998)

The lifespan of Speoplatyrhinus poulsoni is estimated at 5 to 10 years if they survive to adult size. (Kuhajda and Mayden, 2001; Romero, 1998)

There is little to nothing known about behavior in Alabama cavefish. They are likely to be active at any time of the day or night since there is no difference between day and night in these environments.

Speoplatyrhinus poulsoni is blind and therefore must rely on other senses to navigate its environment. The lateral line-system is hypertrophied, sensory papillae on the caudal fin are greatly developed, and visible ridges of neuromasts (tactile sensory organs) are present on the head and body. These are all adaptations to using primarily tactile cues in a pitch-black environment. Tactile and electroperceptile senses have replaced the sense of sight. (Romero, 1998)

No invasive studies have been done due to the species extremely endangered status and the fragility of their cave habitat. It is thought that the diet consists of copepods, isopods, amphipods, and small cavefish. In any case S. poulsoni sits at the top of a food chain that begins with incident grey bat (Myotis grisescens) droppings, or guano. ("Species accounts- Alabama Cavefish", 1991)

These fish have few or no predators because they live in caves with an impoverished fauna. They are top predators in this enclosed ecosystem.

Speoplatyrhinus poulsoni is the top predator in the aquatic environment of Key Cave. (Kuhajda and Mayden, 2001)

There are no negative effects of Alabama cavefish on humans.

Alabama cavefish are a fascinating example of isolated cave evolution.

Speoplatyrhinus poulsoni is the rarest of all American cavefish and is likely one of the rarest of all freshwater fish. There are only an estimated 100 of these fish that live in Key Cave and their population is threatened by groundwater pollution due to the agriculture industry above the cave. Also, local bat populations around the cave have recently been threatened which puts strain on the lowest link in the food chain for S. poulsoni. Low population size and low reproductive potential make S. poulsoni extremely vulnerable. ("Species accounts- Alabama Cavefish", 1991; Kuhajda and Mayden, 2001)