Ectothermic vs. endothermic animals

How blubber helps some animals stay warm

Discovery Place Nature

Today, we will be learning about ectothermic (cold-blooded) and endothermic (warm-blooded) animals and some of the differences between the them.

Ectothermic, or cold-blooded, animals regulate their body temperature using outside sources such as sunlight or heated surfaces. Ever spotted a snake or turtle in a Museum or zoo tank with a lamp shining on it? The warmth from the lamp helps them regulate their body temperature while in the tank, much like laying outside in the sunlight would do in the wild. These animals do not need as much food as endothermic animals to survive. Examples of ectothermic animals include fish, amphibians, reptiles and invertebrates. We can find a lot of these in more tropical areas of the country or even just driving out to the coast to the beach here in North Carolina.

Endothermic animals are warm-blooded animals that have a set body temperature and use internal processes to maintain that temperature no matter their environment. In warm weather, endothermic animals have different ways to regulate their temperature. Some, like dogs, pant when they are warm to release heat through their mouth. Others, like humans, sweat to cool down the surface temperature of the skin. Endothermic animals in colder climates may have a layer of insulation, like fur or blubber, so their heat stays in the body. Since they are able to regulate their own temperature and do not need a specific climate to survive, endothermic animals can be found just about anywhere.

In this activity, we’ll make our own blubber and explore how it helps trap heat inside the bodies of animals like whales and polar bears to keep them warm in some of the coldest places on Earth.

The activity will take approximately 10 minutes to prepare and includes 15-30 minutes of learning time. It is best suited for students in elementary school grades.


  • Pen
  • Paper
  • Vegetable shortening
  • Ziploc baggies
  • Bowl filled with ice and water
  • Spoon or spatula
  • Paper towels


1. Start by taking your Ziploc bags and turning one inside out. (This is so you can zip them both together later.)

2. Now, take the bag that is not inside out and, with your spoon or spatula, put some of the vegetable shortening inside the bag. Fill the bag a good bit.

3. Take the second Ziploc bag and put your hand inside. Slip that bag inside the bag with the shortening in it.

4. Zip the bags together (tape them if needed) so no water can get in. Be sure to spread around the shortening all along both sides of sealed space created by the two bags. Set aside for a moment.

5. Place your bare hand in your bowl of ice and water just long enough to get a good idea of how cold it feels. Remove your hand and dry it.

6. Now, grab your blubber bag, put your hand inside the inner opening (your hand should be surrounded by the blubber trapped in the other layer of the bags) and place your hand inside the bowl of ice and water.

You will notice that it is not as cold as when you put your bare hand in the bowl. That’s because the blubber – vegetable shortening in this case – serves as a layer of insulation!

Want more?

Visualize how temperature affects ectothermic (cold-blooded) animals by buying some thermochromatic paint like this one. Use the paint to color a picture of your favorite cold-blooded animal like a snake, lizard or fish.

After it dries, see how your animal’s color responds to different temperatures. Try touching a spot on your painting. Can you see where your finger or hand made contact with the paint? That’s because you are applying the heat from your body to the paint. Next, put it in the fridge or freezer for a couple of minutes. What happens to the color? Finally, what happens to the color when you place your painting outside on a hot summer day?

Ectothermic animals respond to the cold and heat in a similar way. When they need to get warm, they have to find a place that is warm, like a sunny rock. When they get too hot, they get to a cooler place, like underground or in the shade so that their body cools down.


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