Missouri Cave Life

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Published on: Mar. 2, 2000

Last revision: Nov. 4, 2010

see mosquitoes, flies and midges resting on the cave walls. These flying insects are not restricted to the entrance zone of the cave; they might move deeper into the cave, particularly in winter months.

As we move deeper into the cave, the light diminishes quickly. We have reached what biospeleologists call the twilight zone. Few photosynthetic plants can exist in this dark zone and certainly none live deeper in the cave. We often see animals in this zone that we also saw in the entrance area of the cave. The twilight zone is usually not long. Turns in the cave passage tend to block penetration of light into the cave.

Bedrock fossils, such as fossil coral, crinoids (sea lilies) and brachiopods (shelled creatures), seen in the walls of our caves were once inhabitants of the oceans that extended through what we now call Missouri. In fact, crinoids are the official Missouri state fossil.

As these animals died and fell to the ocean floor they were covered by accumulated skeletons and shells of smaller organisms and eventually became part of the limestone or dolomite bedrock that is so common in Missouri. The fossils were more resistant to dissolving than the limestone, and we are now able to enjoy viewing them in many caves.

We often see evidence--bones, skulls or tracks--of past use of caves by organisms. Explorers have found skulls of extinct saber-toothed tigers or giant lions in Missouri caves. We might see claw marks or the bed of a bear that hibernated in the cave sometime in the past. As black bear numbers increase in Missouri, we might start seeing evidence of new cave use by bears.

If we look in out-of-the way places that haven't been trampled we might find tiny bat bones. Each species of bat has a distinctive skull, mandibles and teeth. We can identify and carbon-date these microfossils. Such studies can help us understand the severity of past glaciations, the habitat requirements of endangered gray bats, and Indiana bats, and the range of climate changes Missouri could expect in the future.

The majority of the area of most larger caves receives no light whatsoever. Some cave ecologists break this dark zone into two separate zones--dark zone with fluctuating temperature and dark zone with constant temperature. Some organisms seem more likely to live in one region or another.

Probably everyone knows bats love caves. Many bats also roost in forests, barns, homes and church

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