troglofauna

thumb|The microscopic cave snail Zospeum tholussum|Zospeum tholussum, found at depths of in the Lukina Jama–Trojama cave system of [[Croatia, is completely blind with a translucent shell]] 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 – 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 longer appendages and a lack of wings.

==Ecological categories== Troglofauna are divided into three main categories based on their ecology: Troglobionts (or troglobites): species, or populations of species, strictly bound to subterranean habitats. Troglophiles: species living mainly aboveground but also in subterranean habitats. These are further divided into eutroglophiles (aboveground species also able to maintain a permanent subterranean population) and subtroglophiles (species inclined to perpetually or temporarily inhabit a subterranean habitat, but strongly associated with aboveground habitats for some functions). Trogloxenes: species only occurring sporadically in an underground habitat and unable to establish a subterranean population.