A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live underground (eutroglophiles), and species that are only cave visitors (subtroglophiles and trogloxenes). [1] Land-dwelling troglobites may be referred to as troglofauna, while aquatic species may be called stygofauna, although for these animals the term stygobite is preferable.
Troglobites typically have evolutionary adaptations to cave life. Examples of such adaptations include slow metabolism, reduced energy consumption, better food usage efficiency, decrease or loss of eyesight (anophthalmia), and depigmentation (absence of pigment in the integument). Conversely, as opposed to lost or reduced functions, many species have evolved elongated antenna and locomotory appendages, in order to better move around and respond to environmental stimuli. These structures are also full of chemical, tactile, and humidity receptors. Troglobites commonly do not survive well outside caves and therefore cannot travel between separate cave systems. As a result, many troglobiotic species are endemic to a single cave or system of caves. [2] [3] [4] [5]
Not all cave dwelling species are considered to be troglobites. An animal found in an underground environment may be a troglophile (a species living both in subterranean and in epigean habitats, e.g. bats and cave swallows) or a trogloxene (a species only occurring sporadically in a hypogean habitat and unable to establish a subterranean population). [1]
No known mammals live exclusively in caves. Most bats sleep in caves during the day and hunt at night, but they are considered troglophiles or trogloxenes. However some fossorials which spend their whole lives underground might be considered subterranean fauna, although they are not true troglofauna as they do not live in caves.
Cambarus is a large and diverse genus of crayfish from the United States and Canada. The adults range in size from about 5 cm (2.0 in) up to approximately 15 cm (5.9 in).
Stygofauna are any fauna that live in groundwater systems or aquifers, such as caves, fissures and vugs. Stygofauna and troglofauna are the two types of subterranean fauna. Both are associated with subterranean environments – stygofauna are associated with water, and troglofauna with caves and spaces above the water table. Stygofauna can live within freshwater aquifers and within the pore spaces of limestone, calcrete or laterite, whilst larger animals can be found in cave waters and wells. Stygofaunal animals, like troglofauna, are divided into three groups based on their life history - stygophiles, stygoxenes, and stygobites.
Troglofauna are small cave-dwelling animals that have adapted to their dark surroundings. Troglofauna and stygofauna are the two types of subterranean fauna. Both are associated with subterranean environments – troglofauna are associated with caves and spaces above the water table and stygofauna with water. Troglofaunal species include spiders, insects, myriapods and others. Some troglofauna live permanently underground and cannot survive outside the cave environment. Troglofauna adaptations and characteristics include a heightened sense of hearing, touch and smell. Loss of under-used senses is apparent in the lack of pigmentation as well as eyesight in most troglofauna. Troglofauna insects may exhibit a lack of wings and longer appendages.
Cave-dwelling insects are among the most widespread and prominent troglofauna, including troglobites, troglophiles, and trogloxenes. As a category of ecological adaptations, such insects are significant in many senses, ecological, evolutionary, and physiological.
Orconectes is a genus of cave dwelling freshwater crayfish, endemic to suitable habitats in the eastern United States. Surface dwelling species, formerly categorised here, were moved to Faxonius in 2017.
Cambarus zophonastes, also known as the Hell Creek Cave crayfish, is named for its original location of discovery, Hell Creek Cave. It is also found in other similar habitats in Stone County and Marion County, Arkansas. These habitats include springs and caves such as Nesbitt Spring Cave in Stone County. C. zophanastes is critically endangered according to the IUCN. C. zophanastes is also protected by the ESA as an endangered species. Currently conservation efforts focus on monitoring populations, reducing disturbances, and monitoring water quality. More research has to be conducted to better understand and conserve the species.
Procambarus is a genus of crayfish in the family Cambaridae, all native to North and Central America. It includes a number of troglobitic species, and the marbled crayfish (marmorkrebs), which is parthenogenetic. Originally described as a subgenus for four species, it now contains around 161 species.
Procambarus leitheuseri, sometimes called the Coastal Lowland cave crayfish, is a species of troglobite crayfish in the family Cambaridae. It is endemic to Hernando and Pasco counties, Florida and is listed as an endangered species on the IUCN Red List.
Stygobromus pecki, the Peck's cave amphipod, is a rare species of crustacean found in four cavern areas of southwestern Texas in the United States. It is a federally listed endangered species in the United States and is also listed as Endangered on the IUCN Red List. Because of the species' limited geographical distribution, not much information on S. pecki is known. As of April 2022, there is no available 5-year review, Species Status Assessment, or recovery plan for the species. However, the Edwards' Aquifer Habitat Conservation Program (EAHCP), with the support of the U.S. Fish and Wildlife Service (UFWS), has been attempting to further study and promote conservation of S. pecki.
Subterranean fauna refers to animal species that are adapted to live in an underground environment. Troglofauna and stygofauna are the two types of subterranean fauna. Both are associated with hypogeal habitats – troglofauna is associated with terrestrial subterranean environment, and stygofauna with all kind of subterranean waters.
Procambarus lucifugus, the Florida cave crayfish, vampire crayfish, or light-fleeing cave crayfish, is a troglomorphic freshwater crayfish endemic to 20–25 occurrences in an arc of caves 80 km long in 6 Florida counties.
Parobisium yosemite, or the Yosemite cave pseudoscorpion, is a species of pseudoscorpion in the family Neobisiidae. A troglobite, the pseudoscorpion inhabits talus caves, formed by voids between boulders, in Yosemite National Park.