A FISH WE RARELY SEE NEVER SEES US

by Whit Gibbons

September 13, 2009

I was recently asked if any cave fish live in the Southeast. The following column, which first appeared 10 years ago, answers the question.

"It's a fish!" That seemingly innocuous declaration was the most exciting statement I had heard in months. A few minutes after this announcement was made, I was sitting in mud and water, and I was enveloped by darkness blacker than the deepest night. My companions and I were alone in the inky blackness; out of touch with the rest of the world--no phone, no radio, no other means of communication. We were having a great time. All this fun came from being an ecologist in search of hidden treasure in a cave.

Tom and Huck found gold; what we found was equally exciting to us. Kurt Buhlmann of the Savannah River Ecology Laboratory had just sighted and was about to catch the first southern cavefish discovered in Georgia in decades. In this particular cave in northern Georgia, a group of spelunkers, or cave explorers, had caught the first, and until now the last, of these little white fish in 1969.

Cavefish live beneath the earth in parts of the United States and the world, but due to their unusual lifestyle in waters of perpetual darkness, few scientists ever see them. Perhaps they are more common than we think, for our interface with cavefish habitat is superficial. We can find them only at the limited points at which underground lakes and rivers can be reached through caves, our only windows to an environment no one has ever seen in its entirety. But as this is the only place to look, that's what some spelunkers do.

Many scientists spend years in search of rare cavefish. When we found this one, we had been peering into the crystal clear edges of an underground river, looking for life. We had been underground for an hour and had come to the end of a winding, narrow tunnel of water, hundreds of feet from the entrance.

The water was moving slightly, enough to change the muddy cloud left by our feet back to bathtub clear in a couple of minutes. I noted this with mild alarm, as it was raining hard outside. Wouldn't that mean the water was rising? Now, seasoned spelunkers like these guys I was with would probably say the water was rising imperceptibly. But I was remembering a narrow squeeze I had, with my face just above the water's surface, to get to the spot where we were. I also noticed that a little line I had drawn a few inches from the water's edge 10 minutes earlier was now submerged.

But rising water or not, I was not about to leave now. For I was sitting at the edge of a deep pool as we watched a southern cavefish flit around a series of tunnels on the far side. Kurt was up to his neck in the water, holding a small dip net, waiting for the fish to move closer. We had tried coaxing it toward us by several means, such as wiggling fingers in the water, turning all lights off for five minutes (an experience bordering on eerie), and talking to the fish the way I do to my dog.

The fish paid about as much attention to us as my dog does to me when I explain things to him. Our idea of cutting the lights off was futile, as we soon learned. Cavefish, it turns out, are blind. And by that, I don't mean they have small eyes with poor vision. They have no eyes. Wiggling our fingers didn't work either, but at least this kept us occupied (although that submerged mark in the mud did come to my mind from time to time).

But a cavefish was worth waiting for, and after 30 minutes, Kurt was able to net the fish and get a closer look at this biological treasure. Along with uncovering a biological mystery about a plant or animal, finding a rare species is one of the most stimulating field experiences a naturalist can have.

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