Fish with no eyes spotted in Texas cave

Scientists thought this rare eyeless catfish only lived in Mexico. Now they’ve spotted one in Texas.

They found it in a deep limestone cave at Amistad National Recreation Area near Del Rio, Texas, and identified it as the endangered Mexican blindcat (Prietella phreatophila).

“Since the 1960s there have been rumors of sightings of blind, white catfishes in that area, but this is the first confirmation.”

The Mexican blindcat, a species that grows to no more than 3 inches in length, is known to dwell only in areas supported by the Edwards-Trinity Aquifer that underlies the Rio Grande basin in Texas and Coahuila.

Discovery of the fish in Texas adds weight to the theory that water-filled caves below the Rio Grande may connect the Texas and Mexico portions of the aquifer.

“Since the 1960s there have been rumors of sightings of blind, white catfishes in that area, but this is the first confirmation,” says Dean Hendrickson, curator of ichthyology at the University of Texas at Austin. “I’ve seen more of these things than anybody, and these specimens look just like the ones from Mexico.”

Life in total darkness

Jack Johnson, a caver and National Park Service resource manager at Amistad, first spotted some of the slow-moving, pinkish-white fish with no eyes in April 2015. After several attempts to relocate the species, he and biologist Peter Sprouse of Zara Environmental LLC found the fish again last month.

Mexican blindcats are a pale pink color because their blood can be seen through their translucent skin and they dwell exclusively in groundwater.

How life in the dark changed crustacean brains

“Cave-dwelling animals are fascinating in that they have lost many of the characteristics we are familiar with in surface animals, such as eyes, pigmentation for camouflage, and speed,” Sprouse says. “They have found an ecological niche where none of those things are needed, and in there they have evolved extra-sensory abilities to succeed in total darkness.”

The Mexican blindcat was originally described in 1954 when found in wells and springs near Melchor Múzquiz in the northern Mexican state of Coahuila. It was subsequently listed as an endangered species by the Mexican government, and as a foreign endangered species by the US Fish and Wildlife Service. Hendrickson led efforts to locate additional blindcat sites in Mexico and Texas for years but only located them in Mexico on previous expeditions.

“Aquifer systems like the one that supports this rare fish are also the lifeblood of human populations and face threats from contamination and over-pumping of groundwater,” Johnson says. “The health of rare and endangered species like this fish at Amistad can help indicate the overall health of the aquifer and water resources upon which many people depend.”

The finding brings the number of blind catfish species within the US to three, all found only in Texas. The two other species of blind catfish in Texas, the toothless blindcat (Trogloglanis pattersoni) and the widemouth blindcat (Satan eurystomus), live in part of the Edwards Aquifer complex, the deep Edwards pool below the city of San Antonio.

Source: University of Texas at Austin

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Source: Futurity