The widemouth blindcat (''Satan eurystomus'') is a
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
North American freshwater catfish
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography.
Etymology
The word ''north'' is ...
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to
Texas
Texas ( , ; or ) is the most populous U.S. state, state in the South Central United States, South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the we ...
in the United States. It is the
only species in the genus ''Satan''.
Description
It was first discovered inhabiting a well, and is adapted for a lightless underground environment. Like other
cavefish
Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, Troglomorphism, troglomorphic fish, troglobitic fish, stygobitic fish, phreat ...
, the widemouth blindcat lacks pigmentation and has no externally visible eyes. The eye remnants are
extremely reduced in size with very little or no trace of a
retina
The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...
or
lens
A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...
; the
optic tract
In neuroanatomy, the optic tract () is a part of the visual system in the brain. It is a continuation of the optic nerve that relays information from the optic chiasm to the ipsilateral lateral geniculate nucleus (LGN), pretectal nuclei, and su ...
is present, but always regresses before reaching the brain. The
swim bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ (anatomy), organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift ...
in these fish is reduced, and the skull is mostly
cartilaginous
Cartilage is a resilient and smooth type of connective tissue. Semi-transparent and non-porous, it is usually covered by a tough and fibrous membrane called perichondrium. In tetrapods, it covers and protects the ends of long bones at the joints ...
and not well-
ossified
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
, unlike the adults of most larger ictalurids. The
lateral line
The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...
is fragmentary and never reaches past the anterior part of the
anal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...
. This species also has a few
paedomorphic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny in modern humans is more signi ...
traits (indicated by small size, kidney morphology, and weak ossification of the skeleton).
This species grows to about
TL.
Taxonomy
The widemouth blindcat's closest relative is the much larger
flathead catfish
The flathead catfish (''Pylodictis olivaris''), also called by several common names including mudcat or shovelhead cat, is a large species of North American freshwater catfish in the family Ictaluridae. It is the only species of the genus ''Py ...
(''Pylodictis olivaris'').
Distribution and habitat
Along with the related
toothless blindcat (''Trogloglanis pattersoni''), this species is distributed in five
artesian wells penetrating the San Antonio Pool of the
Edwards Aquifer
The Edwards Aquifer is one of the most prolific artesian aquifers in the world. Located on the eastern edge of the Edwards Plateau in the U.S. state of Texas, it is the source of drinking water for two million people, and is the primary water su ...
in and near
San Antonio
San Antonio ( ; Spanish for " Saint Anthony") is a city in the U.S. state of Texas and the most populous city in Greater San Antonio. San Antonio is the third-largest metropolitan area in Texas and the 24th-largest metropolitan area in the ...
, Texas.
[ These fish have been found with ]crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
exoskeleton
An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the internal organs, in contrast to an internal endoskeleton (e.g. human skeleton, that ...
s in their stomachs, and may be the top carnivore in their habitat.
Conservation
The widemouth blindcat is a vulnerable species
A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...
, and is threatened by groundwater pollution
Groundwater pollution (also called groundwater contamination) occurs when pollutants are released to the ground and make their way into groundwater. This type of water pollution can also occur naturally due to the presence of a minor and unwant ...
.[ In 2023, the U.S. Fish and Wildlife Service proposed to list the species as endangered under the ]Endangered Species Act of 1973
The Endangered Species Act of 1973 (ESA; 16 U.S.C. ยง 1531 et seq.) is the primary law in the United States for protecting and conserving imperiled species. Designed to protect critically imperiled species from extinction as a "consequence of e ...
along with the sympatric toothless blindcat.
See also
* Blindness in animals
References
{{Taxonbar, from=Q3760645
Ictaluridae
Cave fish
Endemic fauna of Texas
Freshwater fish of the United States
Fish described in 1947
Taxa named by Carl Leavitt Hubbs