A blue whale
What is the largest animal ever to live on earth? It's not an elephant. It's not a dinosaur. It's the blue whale. The blue is huge. The largest known blue whale was 100 feet long. It probably weighed 160 tons, or 320,000 pounds. Think of it this way. That is as long as three railroad cars and as heavy as 30 elephants or about 1,600 human beings.
An animal that big must eat a lot. Strangely, the blue whale doesn't eat at all in the winter. In the summer, it eats about four tons of food a day. It eats very small sea animals called krill.
You might wonder how a very large animal could catch enough very small animals to eat. Here is how the blue whale eats. It does not have teeth. Instead of teeth, it has something called baleen. The baleen hangs down from the whale's upper jaw. It is like a huge strainer. The whale takes a big gulp of sea water. The water is full of krill. Then the whale uses its huge tongue to push the water out of its mouth through the baleen. The krill stay in the whale's mouth. Then the whale swallows the krill