Bowhead whales live in cold Arctic waters near sea ice. A bowhead whale has a layer of blubber about 1.5 to 2 feet thick. It keeps the whale warm in icy Arctic water. Scientists think some bowheads may live to be over 200 years old.

Humpback whales sing songs, so people call them the singing whale. Humpback whales eat krill and small fish. They blow a curtain of bubbles that bunches fish together. Then they feed on them. They often do this as a team. Humpbacks swim thousands of miles each year. They go between cold feeding waters and warm waters.

The blue whale is the largest animal that has ever lived on Earth. Its heart is as big as a small car. The biggest whales eat tiny animals called krill. A blue whale eats several tons of krill in a day. Estimates run from about 3 to 8 tons.

A gray whale feeds by sucking up mud from the sea floor. It strains out food.

Narwhals live in the cold Arctic Ocean. A narwhal's long tusk is really a tooth. The tusk spirals to the left. It can grow almost 10 feet long.

Words to know

• blubber: thick body fat
• tusk: a long tooth
• krill: tiny sea animals