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 a lack of wings and longer appendages. Xenofauna Xenofauna, theoretically, are alien organisms that can be described as animal analogues. While no alien life forms, animal-like or otherwise, are known definitively, the concept of alien life remains a subject of great interest in fields like astronomy, astrobiology, biochemistry, evolutionary biology, science fiction, and philosophy. Other Other terms include avifauna, which means "bird fauna" and piscifauna (or ichthyofauna), which means "fish fauna". Treatises Classic faunas Linnaeus, Carolus. Fauna Suecica. 1746 See also Biodiversity Biome Ecology Ecosystem Environmental movement Fauna and Flora Preservation Society Gene pool Genetic erosion Genetic pollution Natural environment Soil zoology References External links "Biodiversity of Collembola and their functional role in the ecosystem" (by Josef Rusek; September 1998) Animal ecology Ecology terminology Organisms