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Cooling Off: How Do Elephants Use Their Ears to Cool Their Bodies?

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Author: Janice VanCleave

Problem: How do elephants use their ears to cool their bodies?

Materials

  • 3 × 5-inch (7.5 × 12.5-cm) index card
  • Paper towel
  • Water

Procedure

Cooling Off

Cooling Off

  1. Hold the index card about 4 inches (10 cm) above the skin on your arm.
  2. Quickly fan the index card back and forth about 10 times.
  3. Observe any cooling of your skin due to the fanning paper.
  4. Wet the paper towel with water.
  5. Rub the wet towel over the surface of your arm.
  6. Hold the index card about 4 inches (10 cm) above your wet arm.
  7. Quickly fan the index card back and forth about 10 times.
  8. Again observe any cooling effect on the skin.

Results

The wet skin feels cooler when fanned than does the dry skin.

Why?

The cooling effect is due to the evaporation of the water from the skin. Evaporation occurs when a liquid absorbs enough heat energy to change from a liquid to a gas. The water takes energy away from the skin when it evaporates, causing the skin to cool. Elephants use their trunks to spray themselves with water; then they fan their bodies with their large ears. The fanning of their ears, like the index card, increases the flow of air across the skin. The moving air speeds the evaporation of the water and, thus, aids in the cooling of the skin.

Let's Explore

Would an elephant with bigger ears keep cooler? Determine the cooling effect of larger ears by repeating the experiment three times. Each time, increase the size of the index card or other piece of paper. Science Fair Hint: The different sizes of papers and their results can be used as part of a project display.

Cooling Off

Show Time!

  1. Is it the moving air or the evaporation of the water that cools the skin? Demonstrate the cooling effect of evaporation by placing two thermometers on a table. Record the temperature shown on each thermometer. Wet a paper towel with water and place it over the bulb of one of the thermometers. Place a fan so that it blows across the bulbs of both thermometers. Record the temperature shown on each thermometer after five minutes. Photographs of this experiment with the results can be displayed.
  2. Dogs do not have sweat glands in their skin to bring moisture to the surface to evaporate. They stick out their long, moist tongues and quickly draw air in through their noses and out their mouths. This is called panting. How does panting cool their bodies?
  3. Polar bears and humans have about the same body temperature of 98.6 degrees Fahrenheit (37 degrees Celsius), but polar bears often overheat because of their thick fur, skin, and fatty blubber. When a bear's body temperature begins to rise, the bear cools off by turning its face or its rear end into the wind. This cooling method is an example of conductive heat loss. In what other ways is heat lost from the bear's body by conduction?

Cooling Off

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