The largest animal on Earth is the blue whale (Balaenoptera musculus), which can grow to lengths of up to 100 feet (30 meters) and can weigh as much as 200 tons (181 metric tonnes). Blue whales are the largest animals to have ever existed on Earth, even larger than the largest dinosaurs that roamed the planet millions of years ago. Blue whales are found in all of the world's oceans and are known for their distinctive blue-gray coloration and long, slender bodies. They feed primarily on krill, which are small, shrimp-like creatures that they filter out of the water using their baleen plates. Despite their enormous size, blue whales are gentle creatures and are not known to pose a threat to humans.