Background for Teachers - Life in a Cave - Part 1

Cover-Cave Creatures

Life in a Cave - Part 1

Some general cave characteristics to know about SOLUTION CAVES (the most common caves) are:

  • High humidity...(normally 80-100%)
  • Wet and slippery....
  • Some caves also contain gaseous air...(for example sometimes the caves at Colorado Bend State Park are closed to cave crawling because of poisonous air)

CAVE ZONES

The adaptations cave-dwellers have depend on the part of the cave they live in. Each part – or zone – of a cave is very different.

Entrance Zone

Here the cave temperature will have its greatest variation. The temperatures of the entrance zone will be moderated by the meeting of the cave temperature and the outside temperature.

In wintertime, the entrance zone receives warming benefits from the stable cave temperature, while in the summertime, it receives cooling benefits from a constant cave temperature that's lower than the exterior air.

Pack Rat Midden

Packrats are a common "cave visitor," or "trogloxene." Here, we see a huge packrat midden at an entrance zone.

WHAT LIVES HERE?

  • Trogloxenes - "Cave visitors"
    AND...Stygoxenes – aquatic trogloxenes

Twilight Zone

Temperatures in the twilight zone will vary a bit, too, but not as much as the entrance zone. Here you'll find a mix of cave-adapted species and surface-adapted species living together.

WHAT LIVES HERE?

  • Troglophiles "Cave lovers"
    AND...Stygophiles – aquatic troglophiles

Dark Zone

Before you discuss the dark zone with your students, help them paint a picture of it in their minds by writing these phrases on the board:

  • Constant darkness...
  • Completely silent...
  • Stillness to the air...
  • Barren...
  • Stable temperature....(Explain that because of this many troglobites have evolved so that they cannot regulate their own body temperatures – they don't need to. ) Temperatures in dark zones will be stable and the air will be still. The diversity of animal life in the dark zone is low since such special adaptations are needed to survive. Total darkness makes it impossible for your eyes to ever adjust, so nature figured that for some creatures, who even needs eyes? That’s why a common dark zone adaptation is a complete lack of eyes.

WHAT LIVES HERE?

  • Troglobites "Cave dwellers"
  • AND...Stygobites – aquatic troglobites

Adaptations

Adaptations are a huge part of what makes troglobites able to live in caves and their weird (um...unique) adaptations are what make troglobites the most interesting cave creatures of all!

Check out this fascinating video – about 3 minutes long – geared toward educators (it's a bit advanced for the kids) titled, "Levels of Cave Adaptation": http://www.cavebiota.com/media/jeankrejca4.wmv.

What kinds of adaptations do troglobites have that make them so suited to dark cave living? Here are just some examples:

  • The reduction (or lack of) eyes
  • The reduction (or loss of) pigmentation
  • The reduction (or loss of) body size
  • The reduction (or loss of) aggression
  • Extra sensitive sense of smell
  • Some troglobites also exhibit increased lifespans
  • Inability to regulate body temperature

 <== Cave or Cavern ?  |  Life in a Cave, Part 2 ==>


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