Blue whales are the largest living mammal known to live on Earth. They weigh up to 100 feet long and upwards of 200 tons. Their tongues can weigh as much as an elephant, their hearts can weigh up to an automobile.
Blue whales eat a shrimp-like creature called krill. Depending on the time of year, they can eat up to 4 tons of krill a day.
Blue whales have baleen plates attached to their upper jaw. They start with taking in large amounts of water, then expanding the pleated skin on their throat and belly to take it in. The whale's tongue then pushes the water out filtering it out with the laters of baleen plates. Leaving behind large amounts of krill.
Above water, they appear a greyish blue, but underwater, they look true blue. Their yellow toned underbelly is from the millions of microorganisms that make up their skin. The blue whale has a broad flat head and a long tapered body that ends in wide triangular flukes.