When you think of cave animals, you may think of bats or bears but cave life is much more diversified. When I speak of cave animals, I am referring to various groups in the animal kingdom, including mammals, fish, insects and crustaceans.
Many animals use cave entrances as shelters for sleeping, hibernation, safety and reproduction but are not true cave dwellers. The animals that only use the area of a cave near the entrance can be referred to as troglophiles.
These might be smaller mammals like:
Or larger mammals like bears, sheep, cattle, and even elephants in some African caves.
Reptiles such as salamanders, frogs and snakes can be found near cave entrances escaping the heat.
Birds such as swifts, swallows, owls and vultures sometimes use cave entrances for nesting.
An animal that only lives in caves and does not venture out is called a troglobiont or stygobiont for aquatic species but they are both usually referred to as troglobites.
True troglobites often have physical adaptations to cave life such as reduced or no vision, elongated appendages and loss of pigment (no color). For example:
- Snails that live in caves often have thin white shells and smaller eyes.
- Blind cave fish often have no eyes at all and no color.
- The Kauai Cave Wolf Spider also has no eyes.
These adaptations most likely evolved over several million years.
Bats are not true troglobites because they only use caves for sleep and reproduction. Many people assume that they are blind because they use echolocation (sonar) to find their prey when they go out to feed but they actually can see.
Salamanders are common in the southern USA, especially Texas. The troglobiontic species are all lungless and breath with gills.
A very interesting animal, similar to a salamander and sometimes called a “white salamander” is Proteus anguinus or “Human Fish”.
Cave fish mostly live in cave streams and probably got there from surface streams that are swallowed by caves.
Crustaceans, including crabs, shrimp and crayfish are often the largest animals in a cave. But even then, the endangered Alabama cave shrimp is less than an inch long.
The smallest kind of cave animal is a microbe. One cave microbe is Epsilonproteobacteria. That’s a big name for a tiny animal but it plays a big role. It actually plays a part in the formation of the cave itself by dissolving calcium carbonate. The gypsum that is left behind is easily dissolved by water. About 10% of the world’s caves may be formed in this way.
Another microorganism that is more common and more easily seen in caves is abacteria called actinomycete. Their colonies form fluorescent white dots on moist rock. They play a critical role in the processing and breakdown of organic matter.
It is estimated that there are around 50,000 different species of troglobites worldwide if all were accounted for but we will probably never discover them all. Still, new species are being discovered all the time.