HOME

TheInfoList



Click Here for Items Related To - subterranean fauna
OR:
subterranean fauna on:   [Wikipedia]   [Google]   [Amazon]

The endemic_of_Dinaric_Alps.html" ;"title="Endemism.html" ;"title="olm (''Proteus anguinus''), a typical cave dwelling chordate, Endemism">endemic of Dinaric Alps">Endemism.html" ;"title="olm (''Proteus anguinus''), a typical cave dwelling chordate, Endemism">endemic of Dinaric Alps. Subterranean fauna refers to Animal, animal species that are adaptation, adapted to live in an underground Natural environment, environment. Troglofauna and stygofauna are the two types of subterranean fauna. Both are associated with hypogean habitats – troglofauna is associated with terrestrial subterranean environment (
cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as se ...
s and underground spaces above the water table), and stygofauna with all kind of subterranean waters ( groundwater,
aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...
s, subterranean rivers, dripping bowls,
gours Rimstone, also called gours, is a type of speleothem (cave formation) in the form of a stone dam. Rimstone is made up of calcite and other minerals that build up in cave pools. The formation created, which looks like stairs, often extends into fl ...
, etc.).


Environment

Subterranean fauna is found worldwide and includes representatives of many animal groups, mostly
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, o ...
s and other invertebrates. However, there is a number of vertebrates (such as
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, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish and hypog ...
es and
cave salamander A cave salamander is a type of salamander that primarily or exclusively inhabits caves, a group that includes several species. Some of these animals have developed special, even extreme, adaptations to their subterranean environments. Some specie ...
s), although they are less common. Because of the complexity in exploring underground environments, many subterranean species are yet to be discovered and described. Peculiarities of underground habitat make it an
extreme environment An extreme environment is a habitat that is considered very hard to survive in due to its considerably extreme conditions such as temperature, accessibility to different energy sources or under high pressure. For an area to be considered an extrem ...
and, consequently, underground species are usually less than species living in epigean habitats. The main characteristic of underground environment is the lack of sunlight. Climatic values, like temperature and
relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depen ...
, are generally almost stable – temperature corresponds to annual mean temperature in the place where the cavity opens, relative humidity rarely drops below 90%.
Food sources Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...
are limited and localized. The lack of sunlight inhibits photosynthetic processes, so food comes only from epigean environment (through percolating water, gravity, or passive transport by animals). Important food sources in underground habitat are animals being decomposed and bat
guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. ...
, that creates large invertebrate
communities A community is a social unit (a group of living things) with commonality such as place, norms, religion, values, customs, or identity. Communities may share a sense of place situated in a given geographical area (e.g. a country, village, tow ...
in such caves.


Ecological classification

Cave dwelling animals show different levels of
adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
s to underground environment. According to a recent classification, animals living in terrestrial subterranean habitats can be classified into 3 categories, based on their ecology: * troglobionts (or
troglobites 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 u ...
): species strongly bound to subterranean habitats; *
troglophile Troglofauna are small cave-dwelling animals that have adapted to their dark surroundings. Troglofauna and stygofauna are the two types of subterranean fauna (based on life-history). Both are associated with subterranean environments – troglofaun ...
s: species living both in subterranean and in epigean habitats. Troglophiles are also divided in ''eutroglophiles'' (epigean species able to maintain a permanent subterranean population) and ''subtroglophiles'' (species inclined to perpetually or temporarily inhabit a subterranean habitat, but intimately associated with epigean habitats for some functions); *
trogloxene Trogloxenes or subtroglophiles, also called cave guests, are animal species which periodically live in underground habitats such as caves or at the very entrance, but cannot live exclusively in such habitats."Cave Plants and Animals". 9 December Am ...
s: species only occurring sporadically in a hypogean habitat and unable to establish a subterranean population. Regarding stygofauna, the corresponding words stygobionts (or stygobites), stygophiles and stygoxenes are used.


Biology

The cave beetle '' Leptodirus_hochenwartii''_(family_ Leptodirus_hochenwartii''_(family_Leiodidae).">Leiodidae.html"_;"title="Leptodirus_hochenwartii''_(family_Leiodidae">Leptodirus_hochenwartii''_(family_Leiodidae). Characteristics_of_underground_environment_caused_cave_dwelling_animals_to_evolve_a_number_of_adaptation_ In_biology,_adaptation_has_three_related_meanings._Firstly,_it_is_the_dynamic_evolutionary_process_of_natural_selection_that_fits_organisms_to_their_environment,_enhancing_their_evolutionary_fitness._Secondly,_it_is_a_state_reached_by_the_po_...
s,_both_
Leptodirus_hochenwartii''_(family_Leiodidae).">Leiodidae.html"_;"title="Leptodirus_hochenwartii''_(family_Leiodidae">Leptodirus_hochenwartii''_(family_Leiodidae). Characteristics_of_underground_environment_caused_cave_dwelling_animals_to_evolve_a_number_of_adaptation_ In_biology,_adaptation_has_three_related_meanings._Firstly,_it_is_the_dynamic_evolutionary_process_of_natural_selection_that_fits_organisms_to_their_environment,_enhancing_their_evolutionary_fitness._Secondly,_it_is_a_state_reached_by_the_po_...
s,_both_Morphology_(biology)">morphological_and_Physiology.html" "title="Morphology_(biology).html" ;"title="Leiodidae)..html" ;"title="Leiodidae.html" ;"title="Leptodirus hochenwartii'' (family Leiodidae">Leptodirus hochenwartii'' (family Leiodidae).">Leiodidae.html" ;"title="Leptodirus hochenwartii'' (family Leiodidae">Leptodirus hochenwartii'' (family Leiodidae). Characteristics of underground environment caused cave dwelling animals to evolve a number of
adaptation In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
s, both Morphology (biology)">morphological and Physiology">physiological Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
. Examples of morphological adaptations include depigmentation (loss of external pigmentation), a reduction of cuticle thickness and the often extreme decrease of eyesight culminating in anophthalmia (complete loss of eyes). Exceptions, however, are harvestmen (Opiliones) in New Zealand caves, which possess large, functional eyes, presumably because these spider-like chelicerates feed on cave-dwelling, light-emitting glowworm larvae ''
Arachnocampa ''Arachnocampa'' is a genus of nine fungus gnat species which have a bioluminescent larval stage, akin to the larval stage of glowworm beetles. The species of ''Arachnocampa'' are endemic to Australia and New Zealand, dwelling in caves and grott ...
'' which they detect visually. Other adaptations include the development and elongation of antennal and locomotory appendages, in order to better move around and respond to environmental stimuli. These structures are well endowed with chemical,
tactile Tactile may refer to: * Tactile, related to the sense of touch * Haptics (disambiguation) * Tactile (device), a text-to-braille translation device See also * Tangibility, in law * Somatosensory system In physiology, the somatosensory system ...
and humidity
receptors Receptor may refer to: * Sensory receptor, in physiology, any structure which, on receiving environmental stimuli, produces an informative nerve impulse *Receptor (biochemistry), in biochemistry, a protein molecule that receives and responds to a ...
(such as Hamann's organ in the cave
beetle Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...
''Leptodirus'' ''hochenwartii''). Physiological adaptations include slow metabolism and reduced energy consumption, due to limited food supply and low energy efficiency. This is likely to be realized through reducing movements, erasing aggressive interactions, improving feeding capability and food usage efficiency, and through
ectotherm An ectotherm (from the Greek () "outside" and () "heat") is an organism in which internal physiological sources of heat are of relatively small or of quite negligible importance in controlling body temperature.Davenport, John. Animal Life a ...
y. As a consequence, cave dwelling animals can resist without eating for long time, live more than comparable epigean species, reproduce late in their lifespan, and produce fewer and bigger
egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...
s.


Evolution and ecology

Subterranean fauna have evolved in isolation.
Stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers ( strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...
barriers, such as rock walls and layers, and fluvial barriers, such as rivers and streams, prevent or hinder the dispersal of these animals. Consequently, subterranean fauna habitat and food availability can be very disjunct and precludes the great range of observed diversity across landscapes.


Threats to subterranean fauna

Floodwaters can be detrimental to subterranean species, by dramatically changing the availability of habitat, food and connectivity to other habitats and oxygen. Many subterranean fauna are likely to be sensitive to changes in their environment and floods, which can accompany a drop in temperature, may adversely affect some animals. Humans also pose a threat to troglofauna. Mismanagement of contaminants (e.g. pesticides and sewage) may poison subterranean fauna communities and removal of habitat (e.g. rising/lowering of the watertable or various forms of mining) can also be a major threat.


See also

* Cave conservation * List of troglobites * Speleology * Subterranean river *
Trogloxene Trogloxenes or subtroglophiles, also called cave guests, are animal species which periodically live in underground habitats such as caves or at the very entrance, but cannot live exclusively in such habitats."Cave Plants and Animals". 9 December Am ...


References

{{reflist, 24em Cave animals Subterranea (geography) Animals by adaptation Animals by location Ecology