Cave Biology Photo Index

Cave Biology Photo Index

Caves are of great interest to biologists because they are generally isolated from the main nutrient source of the surface world - the sunlight that provides the energy for the surface plants to grow. Since the animals on the surface ultimately depend on the plants for nutrition, neither plants nor animals are found in profusion in caves, like they are on the surface. Even the "cave mud" is (nearly) sterile, unlike surface soil which swarms with microorganisms.

The result of this scarcity of resources is that the community of creatures that do inhabit the caves form relatively simple ecosystems, compared to the surface world. This makes these ecosystems interesting, because the important relationships, like "who eats what", and "where does the waste go", have much simpler answers than they normally do on the surface.

Recent discoveries in the extremely low energy caves of the Southwestern USA have extended these ideas to the world of bacteria. A large number of new species, some with potential medical benefits, have been discovered living in extremely nutrient-poor cave environments.

Most cavers don't notice the microorganisms, or even the small insects and springtails in the cave pools and the mud banks. They do notice, however, the larger visitors that use the cave as a temporary dwelling place or refuge from the surface world. Many a caver has unexpectedly encountered a snake hiding in an entrance passage, a pack rat who has chewed partway through his favorite rope, or a porcupine den with a pile of scat obscuring a passage that needs surveying.

However, the various species of bats are the most common type of mammal found in caves of the USA. Some caves are host to hundreds or thousands of individuals. In fact, the largest concentration of mammals known in the entire world is a bat colony in a Texas cave. Unfortunately, careless behavior of cavers in past decades, and even deliberate mass slaughter, had brought the population of these interesting, beneficial animals to dangerously low levels.

Strong conservation efforts are now taken to protect bats in their most vulnerable environments, such as seasonal prohibitions on visiting caves known to house hibernating bats or maternity colonies. These efforts are beginning to show encouraging results, and novice cavers are now trained to respect and avoid disturbing all cave creatures, whose lives are tough enough without our interference!

You might also want to check out the Biospeleology web site at UTexas, which has quite a few cute pictures of cave life.
photo of two bats on a cave wall These fellows are just sleeping during the day, in preparation for an evening meal of several hundred flying insects each.
closeup photo of a bat that got into the house This confused young bat accidently found its way into the house during its nightly insect hunt and couldn't find its way out again. Fortunately, the house's owner knew enough to kindly escort the bat outside (by allowing it to climb onto a laundry basket) rather than trying to kill it with a broom.
photo of Of course, some bats are just party animals, and are now too fat to fly!
Mushroom spores don't need light to grow, but they don't live very long. Usually a mushroom indicates some recent contamination from the surface, possibly brought in by a caver or recent flood.

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