Southern cavefish use touch and their thigmotaxic sense to maintain their position in the water column. Their use their sense of touch extensively to detect prey. Other sensory modalities are possible, but are unknown currently.
Perception Channels: tactile ; chemical
There are no known predators of southern cavefish.
Typhlichthys subterraneus is a small fish reaching a maximum length of 9 centimeters. Individuals have large broad heads with rudimentary eyes hidden under the skin. Normally there is no pigment on the body, although tests have shown that coloration does appear if a specimen is removed from its habitat and exposed to light. Southern cavefish do not have pelvic fins. There are 7-10 dorsal rays, 7-10 anal rays, and 10-15 caudal rays. The body, head, and caudal fin is covered by sensory papillae.
Range length: 9.0 (high) cm.
Average length: 8.6 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
The expected life span is four years in the wild.
Typical lifespan
Status: wild: 4.00 (high) years.
Average lifespan
Status: captivity: 4 years.
Southern cavefish inhabit subterranean waters and are troglobitic. They prefer caves that are near the watertable and have low energy flows. These caves have water temperatures of 10 to 15 degrees C. Southern cavefish have adapted to life in an extreme habitat that includes factors such as low food supply, seasonal water level changes, and an aphotic environment.
Habitat Regions: temperate
Typhlichthys subterraneus is restricted in its geographic range to the North American continent. Some scientists believe their range was continuous in the past and may still be, but it is difficult to determine. Many scientists agree the range is now disjunct, with species inhabiting specific cave systems in Tennessee, Alabama, Missouri, Arkansas, Oklahoma, and Kentucky, but always south of the limit of glaciation. Dispersal is presumed to be through underground water channels.
Biogeographic Regions: nearctic (Native )
Food is scarce. Typhlichthys subterraneus forages using its sensory papillae in midwater and on the substrate. When prey is within 10 mm of the mouth, capture movements are commenced. Southern cavefish have distance perception and spatial memory which aid in foraging behavior. Their diet consists mainly of copepods (60-90%, by volume).
Foods eaten include trichopteran larvae, tendepedid larvae, cladocerans, isopods, crayfish, and copepods.
Animal Foods: insects; aquatic crustaceans
Primary Diet: carnivore (Eats non-insect arthropods)
These animals are the top predators in the environments in which they live.
Southern cavefish are important members of their ecosystems and important research subjects for understanding evolution in extreme environments.
Positive Impacts: research and education
There are no adverse effects of southern cavefish for humans.
Eggs are held in the gills of females until they hatch. Otherwise, little is known of development in southern cavefish.
Because the habitat of southern cavefish is so unique and because population numbers are normally low, they are regarded as a vulnerable species. Any amount of habitat that is destroyed or altered would have a significant impact. However, many of the cave systems inhabited by Typhlichthys subterraneus are protected by govenmental regulation (e.g., Mammoth Cave in Kentucky).
US Federal List: no special status
IUCN Red List of Threatened Species: vulnerable
Southern cavefish are well-adapted for their environment. Low growth and metabolic rates as well as eye degeneration and pigment loss decrease the amounts of expended energy; parental care of young increases their chances of survival; and a well-developed sensory papillae network and spatial memory aids in navigation.
It has been suggested that the extent of eye and pigment degeneration may be a reflection of the length of isolation in caves and thus would be a helpful tool in determining the ancestral phylogenies of Typhlichthys subterraneus and other species within the family Ambloypsidae.
There is little known of mating behavior in southern cavefish.
Breeding is presumed to occur in the spring season when, unfortunately, the caves are inaccessible due to high water levels.The rise in the water table drives a temperature and alkalinity decrease and also results in an increase in food availability. In response to such stimuli, a hormone is released and the gonads complete their maturation. Females are low in fecundity, producing an average of 49 eggs per female that range from 2.0-2.3 millimeters in size. It is estimated that 50% of adult females breed each year. Because of this, population sizes are small, and as a result, mates are difficult to find. Therefore, a great amount of energy is put into the rearing of young.
Breeding interval: Breeding occurs each year.
Breeding season: Breeding is thought to occur in spring.
Average number of offspring: 49.
Range age at sexual or reproductive maturity (female): 2.0 (high) years.
Range age at sexual or reproductive maturity (male): 2.0 (high) years.
Key Reproductive Features: iteroparous ; seasonal breeding ; sexual
Eggs are incubated in the gill chambers of the parent female for an unspecified amount of time. Fry have been recorded in June and July.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
Typhlichthys subterraneus, the southern cavefish, is a species of cavefish in the family Amblyopsidae endemic to karst regions of the eastern United States.[1]
T. subterraneus is a one of five obligate troglobitic species in Amblyopsidae. T. subterraneus is currently the only member of the genus Typhlichthys,[2] but it may be a cryptic species complex.[3]
The southern cavefish was described by Charles Frédéric Girard in 1859 from a well near Bowling Green, Warren County, Kentucky.[4] Later, Eigenmann in 1905 described both T. osborni and T. wyandotte based on differences in head width and eye diameter.[5] Typhlichthys osborni was described from Horse Cave, Kentucky, whereas T. wyandotte was described from a well near Corydon, Indiana, that was later destroyed. In 2002, a well-like entrance into a cave on the property of a car dealership in Corydon was discovered and is believed to represent the type locality.[6] Regardless, this species is generally considered invalid and was not listed as a locality in a review of the genus in 1957. In this review, all Typhlichthys populations were included in T. subterraneus, as they were unable to find any clear geographic pattern in morphological variation.[7] Recent surveys in the vicinity of Corydon have failed to document T. subterraneus, finding only Amblyopsis spelaea. The most likely contender for recognition as a separate species is Typhlichthys eigenmanni Charlton, 1933, described from Camden County, Missouri. This name has often been considered invalid as a nomen nudum, but in 2006 it was shown that the name is available and a subjective synonym of T. subterraneus.[8] Although the various populations are very closely related, T. subterraneus was considered a cryptic species complex (rather than a single species) based on genetic evidence in 2011. Based on this study, the Ozark highland population should be recognized as the species T. eigenmanni.[3]
A population from Sloans Valley Cave, Pulaski County, Kentucky, differs in several ways from populations to the southwest in Tennessee along the Cumberland Plateau and might represent an undescribed species.[9]
This species is more commonly known as the Southern cavefish. This name is due to the southern states in which it is found, including Indiana, Alabama, Kentucky, Georgia, Missouri, Tennessee, Arkansas, and Oklahoma. The subterranean waters where the cavefish is found is divided by the Mississippi River. The regions that it occupies include the Ozark plateau of central and southeastern Missouri and northeastern Arkansas, the Cumberland and Interior low plateaus of northwest Alabama, northwest Georgia, central Tennessee and Kentucky, and southern Indiana. It has been observed that the species lives in solitary habitats and is mostly isolated.[10]
Tyhplicthys subterraneus is mostly lentic, but can also be found in pools of streams near water tables. The cavefish feeds mostly on aquatic arthropods, such as amphipods and isopods. However, their metabolic rates are depressed in order to survive food shortages.[11] The reproductive capabilities of this species is considerably low, with fewer than 50 eggs per female. This provides restrictions on its capabilities for recovering from an even minor population decline. When young are produced, they brood in the female's gill chamber. Sexual maturity requires approximately two years, and the life span is approximately four years.[12]
Typhlichthys subterraneus is listed as near threatened on the IUCN Red List.[1] Due to environmental threats, there has been a recent decline in geographical span and population density. This is perhaps due to pollution, lowering of the water table, flooding of reservoirs, or cave vandalism.[13] Throughout the range of occupation, the cavefish has been placed under various conservation categories. To reduce these detrimental effects, there are several things that can improve the Southern cavefish's status.[14]
{{cite journal}}: CS1 maint: uses authors parameter (link) Typhlichthys subterraneus, the southern cavefish, is a species of cavefish in the family Amblyopsidae endemic to karst regions of the eastern United States.
