As big as the blue whale is, it eats only the tiniest plants and creatures in the ocean. A giant blue whale 100 feet long and weighing nearly 150 tons makes an elephant look small.
The blue whale is perhaps the biggest animal that ever lived. But as big as the blue whale is, it eats the smallest bits of food it can find in the oceans.
The blue whale has no teeth, so it can’t chew food, and its throat is so small that it can only swallow small fish.
So it eats mostly tiny plants and sea creatures called plankton that drift about in the ocean.
Instead of teeth, long stringy plates of whalebone hang like curtains from the top of the blue whale’s mouth. They are used like a strainer.
To eat, the blue whale swims through the plankton with its mouth wide open. The blue whale then squeezes the water out with its big tongue and swallows the plankton trapped on the whalebone. It takes barrels of plankton to fill the blue whale’s big stomach.
There are other toothless whales, but some whales have strong teeth, such as the killer whale, and throats large enough to swallow chunks of food. – Dick Rogers