Subterranean fauna are animals that have adapted to live underground. Troglofauna and stygofauna are the two types or groups of subterranean fauna (based on life-history). Both are associated with subterranean environments – troglofauna are associated with caves and spaces above the water table and stygofauna with groundwater or aquifers. Adaptations to the subterranean environment include a heightened sense of hearing, touch and smell or swimming-like appendages for aquatic animals and loss of under-used or unnecessary senses, apparent in the lack of pigmentation and eyesight of most subterranean fauna.
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Environment
Subterranean fauna are found worldwide and include representatives of many animal groups, namely invertebrates. However, there are a number of vertebrates although they are less common.
Approximately 90% of caves worldwide remain undiscovered due to lack of visible entrances and more habitat exists in fissures, vugs and other spaces. Consequently, many species are yet to be discovered.
Biology
Subterranean fauna have likely adapted to limited food supply and are extremely energy efficient. Reproduction is likely to vary by species, but very little is known.
Evolution and ecology
Subterranean fauna have evolved in isolation. Stratigraphic 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.