Cave

There are three main groups of animals that inhabit caves. These animals are classified by their degree of dependence on specific cave conditions such as amount of light, temperature, atmospheric conditions, and water. Animals that commonly use caves but depend on the outside world for survival, are called trogloxenes. The best known trogloxenes are bats.

Other examples include birds, bears, and crickets. Troglophiles are species that live their entire life cycle within a cave, generally near the entrance, but are also found living outside caves. Cockroaches, beetles, and millipedes are some examples of troglophiles. Certain fungi and algae are also classified as troglophiles. The third classification are troglobites. Troglobites are permanent cave dwellers found deep within the cave system in total darkness, and consequently lack color. These species are either white, transparent, or slightly pinkish. Troglobites have no need for eyes. Accordingly, groups of organisms that once could see, have evolved into eyeless creatures, although some species have retained eye sockets. They rely on their sense of touch to get around. Some examples of troglobites are fish, shrimp, crayfish, salamanders, worms, snails, insects, bacteria, fungi, and algae. Each cave has a self-contained ecosystem, and it is thought that some have not changed for millions of years. As new caves are discovered, speleobiologists regularly find new species of animals.