Blue whales are the largest animals in the world. These whales weigh about 200 tons or more and grow as long as a hundred feet (30 meters). Blue whales get their name from their blue-gray color.
One whale in this picture (top) is wearing a National Geographic Crittercam. Crittercams include video cameras and other information-gathering devices. These can be attached to animals without hurting them. Crittercams help scientists study the animals that wear them.