What Lives In Caves?

Lots of creatures live in caves, even though most people just think "bats". There are the organisms that just visit or live there part of the time (trogloxenes - Latin for "cave" and "guests"), like some types of bats. There are those that live in caves and are specifically adapted to that particular environment (troglobites - cave life), like blind cave fish. And of course, there are those that can live there full time perfectly OK, but that have not developed specific adaptations to the environment, and could easily live outside the cave. Many salamanders fall into this category. Members of this group are called troglophiles (cave lovers).

Of course, living in a cave full time is tricky. There has to be a source of energy, and the sun don't shine there, as the saying goes. Almost all troglobites need energy to be supplied from outside the cave. This can take the form of leaves or carcasses or whatever that wash or fall in (detritus). Decomposers break the bat poop (guano) or detritus down, and act as food for the larger organisms further up the food chain. (Click here for an overhead of a cave food pyramid.) Or, on the other hand, the forms of energy can walk or fly in under their own power. In Borneo, there's a snake (photo at right) that hangs from the ceiling and snags the bats that fly past. And that's not all that uncommon. Other types of snakes in the United States do the same thing (we tell everyone the hard hats are to protect our heads from rocks, but . . .).

There is the tricky question of why organisms often lose their pigmentation (turn clear or white) and their eyes after many generations in a cave. Scientists have shown that traits that go unused for many generations can simply gradually fade out of the gene pool. I'd like to know more about this, if anyone runs across anything. Heck, eyes and pigments do require a lot of upkeep, energy-wise, but to just "pass away . . "? I like the idea that a fish with big bulging eyes is not going to live as long in a pitch black pool full of pointy rocks (and thusly reproduce less) than a fish with smaller eyes (you know, natural selection), but its probably crudola. Sure is fun to careen around the classroom with my hands held in front of my face like huge bulging eyes, though