Too Hot or Too Cold

Sweating is a way people beat the heat. Most endotherms don’t have sweat glands. So, they have other ways to cool down.

Dogs pant. Fennec foxes lose heat through their ears. Kangaroos lick their arms. As the spit dries, it cools their skin. It’s weird, but it works. Ectotherms can overheat, too. Some lizards dig holes to get out of the sun.

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

What if it’s cold outside? Fur and feathers help keep endotherms warm. Ocean mammals are kept warm by fat, called blubber. Endotherms, like birds and mammals, turn up the heat by shivering. This creates heat. It warms the body. Some ectotherms, like bees, shiver, too.

This kangaroo licks its arm to keep cool.

This fennec fox uses its big ears to cool down.

Blubber protects this walrus from the cold.

This lizard digs a hole to cool down.  

Endotherm vs. Ectotherm

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

So, which animals have the best chance to survive? If a snake chased a mouse on a cool day, the mouse would probably win. However, the snake needs less food to survive. The mouse must eat every day to stay warm.

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