With the exception of a few bats near the natural entrance, moss growing around the electric lights, and bacteria in the underground stream, there is little animal or plant life in Howe Caverns. However, in many caves the food cycle approaches what is known as a closed ecologic system. In a completely closed system, every organism feeds on and is eventually fed upon by still other organisms within the system. Even though the cave environment shows a higher degree of efficiency than most, cave animals still need help from the outside to survive.
All life depends on sunlight even in the darkest areas of a cave.
In sunlight, green plants make food. Leaves, twigs and plant debris are carried into the cave by rainwater. Inside the cave, bacteria and fungi decompose these materials into simple foods and nutrients. Fungus-eating creatures such as flatworms, isopods and other small animals within the cave system feed on the molds and bacteria. These animals then become food for the larger predators in the cave, including salamanders, crayfish and blind cave fish.