Meet the sperm whale. It is the largest of the toothed whales, and it is dark gray. It dives deep down in the ocean to find food.

An adult male sperm whale is 49 to 59 feet (15 to 18 metres) long. It can weigh up to 45 tons.

A sperm whale's head is about one-third of the length of its whole body. It has one blowhole, on the left side of its head. It also has the largest brain of any animal.

The sperm whale is named after spermaceti. This is a waxy substance in its head.

A sperm whale eats mostly squid. It has large teeth in its lower jaw. It eats about one ton of food in a day.

Sperm whales make clicking sounds. They use echolocation to find food.

Adult male sperm whales usually live alone, except in the breeding season. Female sperm whales and their young travel together in groups.

A mother sperm whale carries her calf for 14 to 16 months before it is born. When it is born, the calf is about 13 feet long. It nurses for two years or more.

So how deep can a sperm whale dive? It can dive deeper than 3,000 feet (about 1,000 metres). It can stay underwater for an hour or more.

Words to know

• echolocation: finding by sound
• spermaceti: waxy substance
• calf: baby whale
• tons: heavy weights