The world's largest animal is the blue whale. It is even bigger than the huge dinosaurs that roamed the earth, millions of years ago. Strangely, much of this huge whale's diet is some of the ocean's smallest animals. Krill, small shellfish, are eaten by the thousands every day by the blue whale. It opens its enormous mouth, drinks in the sea water with its many animals, and then closes its mouth. the whale's tongue, which is as heavy as a large elephant, pushes its dinner into its stomach. Of course, the whale cannot choose the food it will eat. Fish, squid, and even penguins may be eaten with the krill.
The diet of the whale must agree with it, for the blue whale may grow to 100 feet in length and weigh 150 tons.