Cave fauna

The Characteristics of Cave Animals

The subterranean animals used to live as above-ground animals. Throughout the years they adapted to cave habitats and developed or acquired some new characteristics, but simultaneously they lost many features in the process of the so-called regressive evolution. This phenomenon implies the reduction of some acquired features, that is, the development of morphologically simpler forms from morphologically more complex forms. Some of the main adaptations to the underground include the following:

  • Reduction of organs of vision
  • A loss of pigment
  • Elongation of body parts and development of other senses
  • Slower metabolism
  • Longevity
  • Low reproduction level
  • Accumulation of fat reserves
  • Reduction of aggressiveness
  • Discontinuation of day/night activities
  • Discontinuation of seasonal changes and activities
The animals that live in caves are partially or completely adapted to demanding living conditions and they enter the cave or live in it for different reasons. In general, the animals that can be encountered in caves can be divided into the following categories:
  1. Genuine inhabitants of cave habitats (terrestrial troglobionts and aquatic stygobionts)
  2. Partially adapted inhabitants of cave habitats (terrestrial troglophiles and aquatic stygophiles)
  3. Occasional inhabitants of cave habitats (terrestrial subtroglophiles and aquatic substygophiles) due to:
    • Hibernation
    • Reproduction
    • Offspring raising
    • Seeking shelter from unfavourableconditions.
  4. Occasional inhabitants of cave habitats (terrestrial trogloxenes and aquatic stygoxenes)
In contrast with above-ground ecosystems, there are not any plants in the underground and hence non of the primary producers, with the exception of some bacteria. The subterranean organic matter comes from above-ground ecosystems. Therefore, the first level in the underground food pyramid includes different forms of decomposers or “detritophagous” animals, that is, animals that feed on dead organic matter in contrast with the above-ground plant-based ecosystems. The subterranean ecosystems have better energy efficiency, which implies that due to different adaptations animals can use food inputs more efficiently.

Bedek, J., Bilandžija, H., Hamidović, D., Cvitanović, H., Dražina, T., Jalžić, B., Jalžić, V., Kovač konrad, P., Lukić, M., Miculinić, K., Ozimec, R. & Pavlek, M., 2009: Svijet ispod svijeta (World under World), Zagreb, p. 1-79.