Fat Insulation: How Do Animals Keep Warm?

Materials

• 2 cups of shortening
• 2 clear plastic cups
• Two thermometers
• Two plastic gloves
• Ice cubes
• Cold water
• 2 large bowls 

Procedure

1. First, fill up one cup with shortening and the other cup with water. Make sure that both the shortening and water are at room temperature when you start.
2. Place a thermometer into the middle of each cup. Record the temperature and then remove the thermometer.
3. Put the cups into the freezer for half an hour.
4. After thirty minutes, remove the cups and quickly test the temperature before it changes. Which one is colder?
5. Continue the experiment for another thirty minutes or for as long as the temperature in the containers keeps changing.
6. Now, fill up one plastic glove with a cup of shortening.
7. Add cold water into each of the large bowls, then add ice cubes.
8. Once the water is quite cold, place one hand into the plastic glove and the other into the glove with shortening in it. What does the water feel like?
9. Have a helper slide a thermometer into each glove and track the temperature for three minutes.

Results

The container with the shortening, which is fat, will have a higher temperature than the container with water. The glove with shortening will keep your hand warmer than the glove without shortening. 

Why?

Blubber is an insulating layer of fat under the skin. While animals that live in chilly places can’t put on a sweater, they can eat and develop this fatty layer to help them survive. In the deep ocean, the water can get down to 54 °F, and in these super chilly conditions, a layer of fat is what keeps these animals’ internal organs from freezing. Seals and small whales have a few inches of blubber, while larger whales can have a layer up to a foot thick! Blubber is especially important to marine mammals, because cold water leads to more heat loss than cold air. An animal's blubber is also a place where it stores energy when food is scarce.

Blubber is an insulator. An insulator is something that doesn’t easily allow heat to escape. When you placed the thermometer into the “blubber” cup, the shortening in the center of the cup was at room temperature. The shortening around the outside of the cup prevented the heat from escaping. Water is not as good at insulating, and it freezes more quickly than fat does.

The work of an insulator is even more obvious when there is a constant source of heat. In the second experiment, this heat comes from your hand, since you are a warm-blooded mammal. Your hand keeps on sending out heat into the fat you’ve placed around it, and this heat stays close by because that fat is an insulator. When you place your hand directly into the water, the heat from your hand moves into the water because there is no insulator between you and the environment. It’s like heading outside without a sweater on a cold day: your body heat starts to head out into the environment around you. When you wear a sweater, your heat stays close.