Alabama cave shrimp
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| Alabama cave shrimp | ||||||||||||||||||
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| Palaemonias alabamae (Smalley, 1961) |
The Alabama cave shrimp (Palaemonias alabamae) is species of albinistic, obligate cave shrimp. The species was first collected in 1958 by Thomas Poulson. They are found only in two caves in the state of Alabama. Due to its small population and limited range, it is considered an endangered species.
After a search of nearly 200 caves in northern Alabama, the shrimp have only been spotted in two, Shelta and Bobcat Caves, both in Madison County, Alabama. Only about 25 members of the species have been spotted between the two caves since its being listed as endangered in 1988. One reasoning for such a small sighting number may be because of the shrimp's coloring, or the lack thereof. The species is nearly transparent and closely resembles its nearest relative, the Kentucky cave shrimp, only smaller. Some researchers believe the lack of pigmentation indicates that it has probably survived underground without light for thousands of years.
The typical size of the shrimp is about 20 mm or 0.8 inches long. The female of the species tends to be about 0.05 inches longer than the male, and has a longer rostrum. Characteristics that tell the Alabama cave shrimp from the Kentucky cave shrimp are that it usually lacks abdominal scales, with fewer scales on the back. It also has unfaceted eyes that are unpigmented. The species is a nonselective grazer, feeding on protozoans, fungi, and algae that normally enter the caves through groundwater.
The Alabama cave shrimp has a global status of critically imperiled, due to its being found in five or fewer areas. For this same reason, or for some factor making it exceptible to extinction, it has an Alabama state ranking of critically imperiled. Because of these factors, the Alabama cave shrimp has been listed as an endangered species. This was made effective October 7, 1988, by the United States Fish and Wildlife Service.
This species became endangered because of habitat degeneration and contamination. High levels of the pesticide DDT were found in Shelta Cave and Bobcat Cave, apparently leakage from drainage ditches. In addition, the decrease in the population of gray bats contributed to the decline of the shrimp. The shrimp feed on bat excrement, but now the bat population has decreased since the gray bat also has a low reproductive rate.
[edit] References
- Inland Water Crustacean Specialist Group (1996). Palaemonias alabamae. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Listed as Endangered (EN B1+2c v2.3)
