WILD THING

Cave Catfish

Rare aquifer-dwelling species discovered in Texas in 2015.

by Paula Levihn-Coon

Since 1992, Dean Hendrick­son, a fish expert at the University of Texas at Austin, has been studying Mexican blindcats (Prietella phreatophila), endangered aquifer-dwelling catfish that are about the size of a cheese stick.

His lab captives, collected from caving expeditions in Coahuila, Mexico, died for various reasons until only one remained. In 2015, with no funding for research, he gifted this 25-year-old fish to Andy Gluesenkamp, conservation director at the San Antonio Zoo, whose lab specializes in cave creatures.

A few months later, Mexican blindcats were discovered in the Amistad National Recreation Area near Del Rio.

“Bingo!” Hendrickson says. “They turned up in Texas, and I was like, ‘Game on!’”

Fueled by excitement about this discovery, the National Park Service started funding exploratory trips to find caves in the recreation area and inventory the animals, like blindcats, that live there with the goal of protecting them.

“We now have this fantastic federal partner,” says Gluesenkamp, who keeps blindcats in a specially designed lab at the zoo. “It’s a match made in heaven.”
The Mexican blindcat’s ancestors were surface-dwelling fish until about 30 million to 40 million years ago. Powerful geologic activity formed the Edwards-Trinity Aquifer, which extends from Arkansas through Texas to northern Mexico, giving these fish access to underground watery caves formed when water eroded limestone.

Imagine that you are a blindcat. You live in complete darkness in a pool of water in an underground cave with a constant temperature of 76 degrees. Then, one day, during a desert storm, a massive amount of water gushes into the aquifer and inundates the pool you call home. You — and the crickets and worms swept into the aquifer by the storm — are carried away in a powerful river. For a while, the eating is good. Then the water subsides, and you’re marooned in a new pool. You eat the critters in it and then you have no food. And the cycle repeats itself.

The catfish adapted to this unusual environment.

No longer needing to see, they are blind. Instead of fleeing from vibrations in the water, fearing a predator, blindcats swim toward the commotion, hoping for a tasty cricket to eat. Blindcats don’t school for protection because there are no predators.

“They are the great white sharks of their environment,” Gluesenkamp says.

Instead of sleeping at night, blindcats take catnaps 24/7, sometimes sleeping sideways or upside-down because there is no need for a quick escape. They memorize and repeatedly search every crevice and surface in their pool because that’s where their dinner lives. They can live without food for extended periods of time; one in Hendrickson’s lab survived 44 months without food.

With myriad pressures on the Edwards-Trinity Aquifer, from population growth, industry and agriculture on both sides of the border, Hendrickson and Gluesenkamp worry about the health of the aquifer upon which millions of people — and Mexican blindcats — depend for life-sustaining water.

Hendrickson and Gluesenkamp are also studying two blindcat species that live about 1,000 feet beneath downtown San Antonio — the widemouth blindcat (Satan eurystomus) and the toothless blindcat (Trogloglanis pattersoni). Because these fish are almost impossible to acquire, knowledge gained from studying the Mexican blindcat is important.

“There’s great value in having a captive colony of this other blindcat that we can rigorously study,” Hendrickson says. “Then we can make inferences about the deep aquifer ones under San Antonio.”