Only about 5,000 blue whales remain today.
The largest animal in the world, the blue whale can weigh up to 160 tons. That's the same weight as 32 elephants, or 1,600 people.
Blue whales can swim up to 30 miles an hour when frightened.
A blue whale's heart is the size of a small car.
Blue whale calves, or babies, can drink up to 100 gallons of milk a day.
Where do they live?
Blue whales swim long distances from the tropics to Antarctica to the Arctic.
Why are they endangered?
Accidents with ships
Tangled up by fishing gear
(Photo: © Kennan Ward/Corbis)