Like Playing In The Snow Without A Jacket
The Importance of Fat as Insulation

Have you ever been in the snow without a jacket? You find out quickly that you need the insulation to stay warm.

To demonstrate how fat keeps sea mammals warm, students can test this for themselves "first-hand". (Read on and you'll see what we mean.) Try this experiment from Manatee expert Bob Bonde and Whale expert Ann Smrcina. It may be a bit messy, but the experience is worth it!

Materials Needed

  • Bucket
  • Ice and water
  • Rubber gloves
  • Crisco (vegetable shortening)
  • 2 Thermometers

1. Fill a large bucket with ice water (3/4 full).

2. Fill a plastic bag with Crisco.

3. Put a rubber glove on one hand. Now put that hand into the Crisco, so the glove is fully covered with Crisco.

4. Submerge both hands — one bare, and the other with the glove and Crisco — into the bucket of ice water.

  • How long can you keep your unprotected hand in the water?
  • How long does it take before you can feel the cold through the fat-insulated hand?
  • How long can you keep this hand in the water?

5. Thermometer Test

  • Submerge one thermometer into ice water and record the temperature of the water. How long does it take for the thermometer to drop to the temperature of the ice water?

  • Next, put a thermometer inside the Crisco-covered glove that you used in the first experiment. Before you submerge the thermometer, make a prediction of how long you think it will take before this thermometer registers the same temperature as the ice water. After you submerge the thermometer, record the temperature each minute.

National Science Education Standards

  • Objects have observable properties, including size, weight, shape, color, temperature, and the ability to react with other substances. Those properties can be measured using tools, such as rulers, balances, and thermometers.
  • All organisms must be able to obtain and use resources, grow, reproduce, and maintain stable internal conditions in a constantly changing external environment.

Special thanks to Bob Bonde & Cathy Beck, USGS Sirenia Project