Why Is a Whale Not a Fish?

Step 1 of 5

A whale holds its breath.

A fish has gills that strain air out of water, so it never surfaces. A whale has lungs like yours. It fills them at the top, dives, and everything it does down there happens on one breath.

Step 2 of 5

The spout is not water.

The plume you see is the whale's warm breath turning to mist in cold air, exactly like your breath on a winter morning — with a little seawater flicked up from around the blowhole.

Step 3 of 5

It is warm inside, all the time.

A fish is as cold as the water around it. A whale keeps itself warm whatever the sea is doing, which is why it can live under the ice and a goldfish cannot.

Step 4 of 5

Whale babies drink milk.

A calf is born tail first, pushed straight up for its first breath, and then fed on milk so thick it is nearly a paste — which is how it puts on weight fast enough to survive cold water.

Step 5 of 5

Nothing has ever been bigger.

A blue whale is bigger than any dinosaur that ever walked. Its heart is the size of a small car, and its tongue alone weighs as much as an elephant.

A blue whale eats some of the smallest animals in the sea. It takes a room-sized mouthful of water and strains out shrimp the size of your fingernail.