Ever wanted to meet Satan?
You can - 1,200 feet (365m) below the surface of San Antonio, Texas. Satan lives in the rocks, or more specifically, in the long and dark crevasses, rivers, and caves carved out of the rocks the rocks. In those crevasses lays the Edwards Aquifer [top image]. This aquifer is split into two biomes - the “Good Water” zone, where there is low salinity and high oxygenation, and the “Bad Water” zone, which has water which is brackish, sulfuric, and anaerobic (lacks oxygen).
These two zones meet at a steep drop off, which runs close to Interstate 35, where the aquifer plunges down to 3,000 feet (915m) below the surface, and this mixing zone is where the Widemouth blindcat (Satan eurystomas) is king - the top predator of its biome.
Despite extensive work being done to preserve the habitat of several endangered species known to exist in the aquifer and headwaters, such as the Texas blind salamander (Eurcea rathbuni) and fountain darter (Etheostoma fonticola), very little is known about the Widemouth blindcat, due to its extreme depth and generally inaccessible habitat. Despite having few specimens to work from, we do know that this species is probably most closely related to the flathead catfish [bottom image] (Pylodictis olivaris), and has the strong jaw, well-developed teeth, and barbels of its nearest relative. Unlike the often-massive flathead, the maximum size of the blindfish is estimated to be around 6 inches (14 cm).
Like most animals adapted to cave life, Satan eurystomas has no pigment in its skin, no eyes (its optic tract is present in the brain, but never forms eyeballs), and is partially neotenous. In addition to these adaptations, this fish also has a reduced swim bladder that is largely composed of fatty tissue, probably as a result of the great pressure it lives under.
While current populations are believed to be relatively stable, the conservation efforts to save the more charismatic Texas blind salamander have also been helping the blindcat. Because they have such a limited range, depletion of the aquifer or introduction of pollution into their habitat could easily lead to extinction.