Keep It Steady

Endotherms and ectotherms have various ways of controlling their temperature to keep from getting too hot or too cold. Here’s one that you’ll know: sweating.

Sweating keeps an endotherm’s body from overheating. Here’s what happens. First, nerves send messages to your brain that you are heating up. The brain then sends messages to sweat glands all over your body to produce sweat, which is mostly water. The moment sweat appears on your skin, heat moves from your body to the water. As sweat evaporates from your skin, you cool down.

Dogs don't sweat.
Instead, they pant to cool down.

How to Beat the Heat

Most endotherms don’t have sweat glands. Yet, they have other ways to cool down. For example, dogs pant. With each breath, moisture evaporates from their tongues and cools their bodies. Birds pant, too, but not in the same way that dogs do. Birds open their mouths and flutter, or vibrate, their neck muscles. This action releases heat from their throats.

Many animals use their ears to beat the heat. An elephant’s large ears have many veins. Heat from the warm blood flowing through the veins works its way through the ears’ thin skin and into the air. The cooled blood continues circulating through the body.

This kangaroo licks its arm to keep cool.

This fennec fox uses its big ears to cool down.

Kangaroos do something else. When the hot Australian air gets to be too much, they lick their forearms. As their spit evaporates, the blood flowing through their arms close to the skin cools. A little gross, maybe, but it works for the kangaroos.

Ectotherms can overheat, too. Some lizards burrow into the ground to keep cool.

This iguana isn’t trying to hibernate.
It’s hiding from the sun on a hot day.

How to Turn Up the Heat

When the weather turns cold, ectotherms, such as reptiles and amphibians, burrow into the ground to wait out the winter. They hibernate. So do some insects, like ladybugs. Other insects, like monarch butterflies, stay warm by flying to warmer climates.

This walrus’s layers of blubber help insulate it from the cold.

Endotherms have another way to turn up the heat: They shiver. When you are cold, your brain signals your muscles to vibrate. Rapid muscle movements generate heat to warm your body. Mammals and birds shiver, but you may be surprised to learn that some ectotherms, such as bees and dragonflies, do, too.

Endotherms have body coverings that keep them warm. Hair, fur, or feathers keep the cold air out and the body heat in. Wolves, foxes, and many other mammals grow extra fur to protect against cold weather. Seals, whales, and walruses grow thick layers of fat called blubber. It helps keep these marine mammals warm as they swim in icy ocean waters.

Endotherm vs. Ectotherm

So, which animals have the advantage to survival? Endotherms can move quickly in
a cold environment, whereas ectotherms
can hardly move at all.
If a snake was trying to catch a mouse on a cool day, the mouse probably has the advantage. However, the snake requires a lot less food than the mouse does. The mouse has to eat every day in order to maintain a high metabolism and body heat. The snake could go for at least a week without a meal.

Endotherms can live almost any place on Earth, from hot dry deserts to the icy Arctic. Ectotherms are plentiful only in warm and mild climates. They can’t survive in places that are cold all year.

It’s hard to say which has the upper hand. It looks like both ectotherms and endotherms have unique ways to survive.

A mouse is an endotherm. A snake is an ectotherm.