It is believed that no animal — living or dead — has ever been larger than the blue whale. This giant marine mammal can grow up to 120 feet in length and weigh more than 100 tons. Like other large undersea animals, the blue whale reaches its massive size by feeding on microscopic animals known as krill. To maintain its immense weight, a blue whale must spend its day filtering krill out of tens of thousands of gallons of water it sucks into its mouth. The blue whale is a filter feeder which means it uses a filtering system in its mouth known as baleen. Baleen resembles the bristles in your hairbrush. When ocean water is pulled through a blue whale’s mouth the baleen separates the krill from the water, allowing it to be pulled into the whale’s digestive track. The water is then squeezed out of the whale’s mouth and back into the ocean.
Blue whales are gentle and slow-moving. They migrate from the Equator to the South Pole in small packs. In the early part of this century, blue whales were nearly hunted into extinction by whalers who were eager to use the huge animals for their blubber. In the 1960s, all the nations around the world banned the hunting of blue whales. Since then, the number of these gentle giants has grown slowly but steadily.