Widemouth Blindcat

There are no known predators of Satan eurystomus.

Widemouth blindcats generally have similar physical characteristics to other members of the Family Ictaluridae. The most notable difference being that they have no eyes. They are white or pink in color because they lack skin pigmentation. The head is wide and flat and they have barbels. The lips thicken at the corners and the mouth appears as if they have a slight overbite. The gills have separate membranes and contain strong folds. The adipose fin is high and long while the anal fin is rounded and short, with approximately 20 rays. The caudal fin is either slightly notched or straight.

Range length: 30 to 117 mm.

Average length: 70 mm.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Little is known about the lifespan and longevity in Satan eurystomus. Slower growth and longer life than related species has been seen in similar troglobitic fish species.

Widemouth blindcats live in the fresh waters of the subterranean Edwards Aquifer. These waters ranges from 305 to 582 m below the surface.

Range depth: -305 to -582 m.

Habitat Regions: temperate ; freshwater

Aquatic Biomes: rivers and streams

Other Habitat Features: caves

Satan eurystomas is an odd name. The Latin name is translated as "widemouth prince of darkness". Carl Hubbs, who named this species, seemed to have an affinity for giving diabolical names to cave fishes. His reasoning for this was that Hell was underground. Considering that widemouth blindcats live exclusively in darkness and may be the apex predator in this habitat, the name "widemouth prince of darkness" may turn out to be more accurate than first imagined.

Little is known about communication and perception in Satan eurystomus. The species is only observed when specimens emerge from artesian wells and are caught in nets. Most that are caught are already dead by the time they are observed by scientists. Widemouth blindcats lack eyes, however, most ictalurid catfishes have well developed olfactory and tactile senses (including their barbels) that widemouth blindcats may also use to navigate their subterranean environment. There are also lateral-line canals and pores on the head, suggesting they use this mode of perception.

Perception Channels: tactile ; acoustic ; vibrations ; chemical

Widemouth blindcats are considered vunerable due to their extreme endemicity and the threat of pollution from agricultural and industrial runoff into the Edwards Aquifer.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: vulnerable

The life cycle is similar to that of other ictalurids. They reproduce sexually. Similar troglobitic fish species have fewer, larger eggs. Some of these species have a low proportion of reproductive females per reproductive event and slower growth rates.

There are no known adverse effects of Satan eurystomus on humans.

Satan eurystomus provides no positive economic importance for humans directly, although they are important members of a unique and amazing subterranean ecosystem. Cave fishes are important in the study of evolution.

Widemouth blindcats are possibly the top predators of the San Antonio pools of the Edwards Aquifer.

Widemouth blindcats are carnivores and detritivores. Upon examining the stomach contents of a few specimens, a mudlike substance was observed, as well as the exoskeletons of crustaceans. There are several known species of crustaceans found in the waters of the Edwards Aquifer, such as Stygobromus russelli. Widemouth blindcats are also able to store extra fat due to a reduced gas bladder. This helps the fish to store more energy when food is scarce. Widemouth blindcats may be top predators in the Edwards Aquifer.

Animal Foods: aquatic crustaceans

Other Foods: detritus

Primary Diet: carnivore (Eats non-insect arthropods); detritivore

Satan eurystomus is known only from the Edwards Aquifer in Bexar County near San Antonio, Texas.

Biogeographic Regions: nearctic (Native )

Little is known about the mating system of widemouth blindcats. It has not been studied in the natural habitat. Specimens which have been studied appeared to be juveniles, having not reached sexual maturity. Among ictalurids, both monogamy and polygamy have been observed. Spawning season usually varies by habitat.

Little is known about the reproduction of widemouth blindcats.

Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous

Little is known about parental investment in widemouth blindcats. In most ictalurid species, parental care has been seen, although it varies among species and sexes.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female)

Due to the inaccessibility of its habitat, little is known about the widemouth blindcat. It is known to eat shrimp, amphipods, and isopods, and may also prey on the toothless blindcat, Trogloglanis pattersoni (5). The widemouth blindcat possesses a well-developed lateral line (a row of receptors that can detect movement via vibrations in water), which is thought to be the primary sense with which it locates prey (6). It is this, along with the frequent presence of crustacean skeletons in its gut, and its muscular stomach, that suggests that the widemouth blindcat may be the top carnivore in the Edwards Aquifer system (6).

In addition to the IUCN classifying the widemouth blindcat as Vulnerable (1), the Texas Parks and Wildlife Department consider this species to be Threatened (9). Controls are placed on water extraction from the Edwards Aquifer by federal and state authorities, offering the toothless blindcat a little protection (8). However, to fully protect this little-known species and the unique aquatic ecosystem it inhabits, further studies and long-term monitoring are required to inform conservation actions (8).

A bizarre looking fish, the appearance of the widemouth blindcat reflects the unique habitat it occupies. Living in dark, underground waters, the widemouth blindcat lacks eyes and its smooth, scaleless skin possesses no dark pigments and so appears white or pink in colour (3) (4). The head and snout are broad and flat (3), with long, whisker-like barbels (fleshy projections) around the mouth (4). It has a long, high adipose fin on the back, and a strong spine in front of the dorsal and pectoral fins (4). It occupies the same underground pools as the toothless blindcat, but can be easily distinguished by its well developed jaw teeth (3).

The widemouth blindcat is a subterranean freshwater fish, inhabiting underground pools at depths of 305 to 582 meters (5).

Occurs only in the San Antonio Pool of the Edwards Aquifer, in and near San Antonio in Bexar County, Texas (3).

Classified as Vulnerable (VU) on the IUCN Red List 2007 (1).

As the widemouth blindcat occurs only in one underground pool, any change in the pool environment could rapidly impact the entire population, making this species very vulnerable to extinction. The widemouth blindcat inhabits water that is removed for human use (7), particularly for the enormous city of San Antonio. As San Antonio continues to grow at a rapid rate, ground water extraction has an increasing impact on the blindcat's habitat (8). In addition, as human populations rise, so does the probability of contamination of the Edwards Aquifer from agricultural and industrial runoff, such as fertilisers, pesticides and heavy metals (5) (7).

Occurs in subterranean waters. Threatened by groundwater pollution (Ref. 10172).

Occurs in subterranean waters. Threatened by groundwater pollution (Ref. 10172).

fisheries: of no interest

The widemouth blindcat (Satan eurystomus) is a species of North American freshwater catfish endemic to Texas in the United States. It is the only species in the genus Satan.