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.