Investigating Cave Crayfish

May/June 2011

Cave CrayfishFreshwater crayfish, also called crawfish or crawdads, resemble small lobsters. Perhaps best known for their place in Cajun culture, they are also commonly found in Florida. The crayfish many people recognize make their homes in bodies of water, including lakes, streams, rivers, marshes, and ponds. A rarely seen relative also dwells in fresh water, but only that beneath the earth's surface. More species of cave crayfish live in Florida than in any other state; currently, 14 species have been found in the state's subterranean areas. Despite sharing some physical features with their surface-dwelling relatives, crayfish that live in the depths of the Sunshine State's caves have some key differences. For example, unlike surface-dwelling crayfish, cave crayfish lack pigment. Cave crayfish are troglobitic, meaning they can survive only in a cave environment. Their adaptations include heightened senses of hearing, smell, and touch, but they lack eyesight. Though it is easy to distinguish them from their relatives on the surface, it is difficult to spot differences between cave crayfish species because they share necessary adaptations to their dark, underground environments.

To confirm that those adaptations are indeed just similarities and not indications that all cave crayfish are the same species, Wildlife Research biologists in 2007 began a study of Florida's cave crayfish. In addition to verifying the existence of the 14 recognized species in the state, FWRI biologists - in partnership with researchers from Brigham Young University in Utah - set out to investigate the possible existence of unrecorded species that appear identical but are genetically distinct, called cryptic species. Project biologists also aimed to compile records that better defined the population distribution of cave crayfish, and they visited caves and springs throughout the state to collect samples. Researchers then conducted genetic analysis of the samples to assess relationships among the species.

The research will increase understanding of cave crayfish, boosting knowledge about the number of species and where each species lives. That knowledge is essential when it comes time to evaluate each species' conservation status and population management needs. The project is part of a broader genetic assessment of all crayfish in Florida, cave and otherwise. The overarching study is set for completion by May 2012.



FWC Facts:
The bowfin, or mudfish, is a ‘living fossil’ and is the only freshwater fish with a gular bone, a bony plate on the exterior of the lower jaw between the two jawbones.

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