[Photo: Texas State University at San Marcos]

Widemouth Blindcat
Satan eurystomus

Description: The widemouth blindcat, of the family Ictaluridae, is 1 of 2 cave-dwelling (troglobotic) catfish in North America. The widemouth blindcat is the only member of the Satan genus, distinguished from the rest of the Ictalurids by its many distinctive cave-adapted features. The widemouth blindcat can grow up to 5.4 inches (13.7 cm) long with a weight of 0.95 ounces (27 grams). This catfish has a broad flat head and snout, small nostrils, well-developed teeth, strong jaws of normal shape and size, and thick lips. It has well-developed barbels (larger than toothless blindcat) which it uses for taste and touch. This catfish has many cave-adapted features. These include its lack of eyes, pale white or pinkish body, a very well-developed lateral line, and lack of an air bladder. The absence of an air bladder, which is present in most fish, makes the widemouth blindcat able to withstand the great pressure in the deep caves it inhabits. This bladder has been replaced by an abundance of fatty tissue for buoyancy.

Life History: The widemouth blindcat is an opportunistic predator and the top carnivore in the subterranean Edwards Aquifer ecosystem. It is believed that it will eat anything that comes into contact with its mouth and finds food using vibrations detected by its lateral line. This is in addition to the touch and taste sensations provided by its over-developed barbels. Its diet consists of detritus, crustaceans, and possibly the toothless blindcat.

Habitat: The widemouth blindcat lives in the subterranean waters of the Edwards Aquifer at depths of 1000-1900 feet (305-582 m) and temperatures of 80 degrees F (27 deg C). This fish lives in habitats under great hydrostatic pressure.

Distribution: Satan eurystomus is restricted to the San Antonio Pool of Edwards Aquifer in Bexar County, TX (256,000 acres [103,600 ha]). The fish has been collected at five artesian wells in the Southern part of Bexar County.

The map below depicts the area where this species has been reported (according to literature review).

Reported Species Distribution of the Widemouth Blindcat (Satan eurystomus) [Figure: Houston Advanced Research Center]

Status: The widemouth blindcat is a state listed threatened species. The population is abundant within its range although, due to the depth of its habitat within the aquifer, it is difficult to sample for them. This population is sensitive due to its restricted range (San Antonio pool), thus a drop in groundwater could pose a risk to this population. This catfish is the top predator in the Edwards Aquifer ecosystem; which makes it useful as an indicator of water quality. This is especially true for the widemouth blindcat because it collects toxins in its extensive fatty deposits.

Resources:

Edwards Aquifer Research and Data Center, Widemouth Blindcat Status

Texas State University at San Marcos, Biology Department, Texas Freshwater Fishes, Widemouth Blindcat Species Profile