Subterranean fauna

The lack of sunlight inhibits photosynthetic processes, so food comes only from epigean environment (through percolating water, gravity, or passive transport by animals).

[1][2] Other important food sources in underground habitats are animals being decomposed and bat guano,[3][4][5] that creates large invertebrate communities in such caves.

According to a recent classification, animals living in terrestrial subterranean habitats can be classified into 3 categories, based on their ecology: Regarding stygofauna, the corresponding words stygobionts (or stygobites), stygophiles and stygoxenes are used.

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 which they detect visually.

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 eggs.

Mismanagement of contaminants (e.g. pesticides and sewage) may poison subterranean fauna communities[13] and removal of habitat (e.g. rising/lowering of the watertable or various forms of mining) can also be a major threat.