Subterranean fauna

Subterranean fauna is referred to animal species adapted to live in underground environment. Troglofauna and stygofauna are the two types of subterranean fauna. Both are associated with hypogean habitats – troglofauna is associated with terrestrial subterranean environment (caves and underground spaces above the water table), and stygofauna with all kind of subterranean waters (groundwater, aquifers, subterranean rivers, dripping bowls, gours, etc.).

Subterranean fauna is found worldwide and includes representatives of many animal groups, mostly arthropods and other invertebrates. However, there is a number of vertebrates (such as cavefishes and cave salamanders), 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 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, 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 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, that creates large invertebrate communities in such caves.

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