A state wildlife grant is providing UA researchers funding to search for cave crayfish – eyeless, small, white, almost transparent animals – within 10 Alabama caves.

These long-antennaed creatures spend their lives underground and have diets that, seemingly, are mud-centered. Some have contended a species of cave crayfish is among the Earth’s longest living organisms, with a possible life span of well over 150 years.

Dr. Bernard Kuhajda, left, escorts a visitor out the mouth of Hering Cave southeast of Huntsville following a multi-hour search for crayfish. (Photos by Zach Riggins)

One species of cave crayfish, Orconectes a. australis – a relative of the above ground crustaceans sometimes called crawdads or mudbugs – is the focus of a project UA researchers hope to expand into a broad-based look into the relationships between caves and the organisms that live within them. The project involves the capturing, measuring, tagging, releasing and, subsequent re-capturing of hundreds of cave crayfish over a three-year period. It is designed to reveal more about the crayfish’s population size, individual growth rates and longevity. The search is not an easy one.

“Crayfish can go a lot of places we can’t,” said Dr. Alex Huryn, a UA freshwater ecologist leading the project. And their homes are places few biologists have explored.

“It’s the final frontier,” said Dr. Bernard Kuhajda of caves. “It’s the great unknown.”

In some ways, caves are the near perfect settings in which to study organisms, said Michael Venarsky, a doctoral student in the UA’s biological sciences department. “They are these nice, little, perfectly replicated laboratory systems all over the world that have similar environmental characteristics. That opens the door for unbelievable comparison studies.”

In other ways, they’re not so ideal.

“Working in surface streams is difficult enough,” Venarsky said, “but working in cave streams is exacerbated by space. There are a lot of caves you have to swim through, that you have to pull your equipment through.” Many cave species are imperiled, so non-lethal means must be developed for sampling efforts. Some cave passages are so cramped explorers must crawl along the caves’ floors, while others require rappelling into 60-foot sink holes. “It’s facing these challenges and difficulties that most people have avoided,” said the College of Arts and Sciences’ doctoral student.

And there’s that small matter of looking for a 2-4 inch creature in the complete absence of all natural light. “What we’re starting to realize,” Venarsky says, “is that these populations appear to be much bigger than initially anticipated.”

Seven of Alabama’s 89 known species of crayfish are cave dwellers. “This is a real hotspot for crayfish diversity, worldwide,” Venarsky said. “These cave crayfish are an important, unique part of that diversity.” Six of the cave species are considered imperiled, and the seventh is believed to be extinct.

“From a conservation point of view,” Kuhajda said, “we always talk a lot about the rain forests – half a world away – and how many species are going extinct. And, we have the same thing happening right here in Alabama.”

Caves have much less variation than most environments, so animals that inhabit them are particularly susceptible to change, said Kuhajda, who recently discovered a previously unknown species of cave shrimp. Cave temperatures, for example, fluctuate little regardless of the season. “As we continue to grow as a population, all creatures are going to have a more difficult time finding an acceptable place to live,” said Kuhajda. “We’ve got a lot of diversity here, but we’ve got a lot to lose. I realize that growth has to occur, but we can do it in an intelligent way.”

This exploration is taking the UA scientists deep underneath Alabama’s soils and may eventually take them beyond the crayfish.

“We are using this as a portal to burst into bigger questions about cave ecology,” Huryn said. “We’re focusing on crayfish. We think it’s an important element in the food webs, but we’re interested in taking this beyond the crayfish. We want to look at the whole cave food webs and look at energy sources in the different groups of caves.”

For more information about cave ecology research, visit UA’s Research Magazine Online at http://research.ua.edu/archive2007/crayfish.htm.

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This story was originally published in Dialog, the official faculty & staff newsletter of The University of Alabama. For more stories, please visit Dialog Online at http://dialog.ua.edu, or the Crimson Spotlight Index.