A wide variety of living beings inhabit the caves. Amazingly, some organisms can spend their entire lives without leaving a cave, finding there the conditions necessary for their survival and reproduction. But most of the animals that we normally associate with caves, such as bats, use them as temporary shelters and at some point have to go out and get food on the surface.
Those animals that develop their entire life cycle within the cave often have very special adaptations to survive in the peculiar cave environment. The complete absence of sunlight is probably the most notable feature in this context. To compensate for the futility of vision, many animals have not only lost their coloration and ability to see, but have also used other forms of guidance, using hearing, smell, and even the ability to perceive electric fields as ways to locate their animals. Food sources, escape from predators and find your mates.
On the other hand, the cave, being a very isolated environment, is also a stable environment, where temperature, humidity and other physical factors vary slightly. Many organisms exploit stability in their favor, such as fungi and bacteria. Others take advantage of the darkness and difficult access to protect themselves from predators, to have their young safe, or, in the case of caves located in temperate regions, to quietly hibernate.
Bats, crickets, owls, spiders, amblyglers, swallows, beetles, cockroaches, as well as various species of fish, shrimps and mollusks, in those caves where there is a perennial river or lake, are examples of the animals we most easily find when visiting a cave. . In Brazil, some species unique to the cave environment have been described, such as the blind catfish in the state of São Paulo. However, there is still much to discover about the caves and their inhabitants.
Caves are very peculiar ecosystems due to their isolation from the surrounding environment. Because sunlight penetration is limited, the cycling patterns of matter and energy differ from those of other terrestrial ecosystems. The most striking feature is the absence of superior vegetables and, consequently, the absence of photosynthesis.
The first or producer level of the food chain of these ecosystems may be restricted to certain types of chemosynthetic bacteria that live in hot springs but, more often, are completely absent. Nevertheless, a great diversity of organisms can be found inhabiting caves. Representatives of all five kingdoms of living things, including various invertebrate phyla and classes of vertebrate animals, have already been registered by science as temporary or permanent occupants of caves.
We can classify cave dwellers according to their degree of dependence on the cave environment in: (i) trogloxenes – depend on the external environment at some stage of their life cycle (bats, owls, frogs, snakes, the jaguar); (ii) troglophils – may develop their life cycle inside or outside the cave (spiders, scorpions, amblypses, opilions) and; (iii) Troglobes – complete their life cycle entirely within the cave (fish, crickets and other insects).
Despite the lack of sunlight, all this biodiversity is sustained by the organic material brought in by the watercourses and / or the accumulating bat feces.
Another important feature of cave ecology is stability. Physical parameters such as temperature and humidity vary very little throughout the day and throughout the year.
Several animal species have specific adaptations to life in these environments. The reduction of vision and the improvement of other senses; reduction of pigmentation of skin thickening; The reduction or disappearance of wings in insects are some examples of adaptations found in many groups of troglobite organisms.