A whale chooses each breath. Breathing is a voluntary act for whales, not automatic as it is for people. Whales hold their breath for many minutes on a dive. It is 7 to 30 minutes for many whales and an hour or more for deep divers like sperm whales.

Whales have to stay at least partly awake to breathe. A blue whale sleeps while still swimming and never becomes fully unconscious. When dolphins and other toothed whales sleep, half of the brain stays awake while the other half rests.

The first whales lived on land. Pakicetus was about one meter long and looked more like a wolf than a whale.

There are two kinds of whales, toothed whales and baleen whales. Baleen whales have no teeth in their mouths. Toothed whales have one blowhole. Baleen whales have two.

A sperm whale has large teeth in its lower jaw, about 20 to 26 on each side. Its upper teeth rarely come through the gums.

A humpback whale mother carries her calf for about 11 months before it is born. A newborn humpback calf is about 13 to 16 feet long. It weighs about 2,000 pounds.

Whale mothers feed their babies milk. A blue whale calf drinks so much rich milk that it can gain about 200 pounds in one day. In fall, gray whales swim south along the west coast of North America to warm lagoons in Mexico, where many calves are born.

Orcas are top predators of the sea. Healthy adult orcas have no natural predators. Orcas hunt together as a team.

Each orca pod has its own sounds. The calls work like family badges. Blue whales are among the loudest animals on Earth.

Ship strikes and getting tangled in fishing gear are two big dangers for whales. As of November 2026, blue whales are still endangered and are protected by law in the United States.

Words to know

• voluntary: by choice
• predators: hunters
• blowhole: a nose hole