The blue whale is the largest animal known to have ever existed on Earth. These magnificent marine mammals can grow up to 100 feet long and weigh as much as 200 tons. They primarily feed on tiny shrimp-like animals called krill, consuming up to 4 tons of them each day during feeding season. Blue whales are found in oceans worldwide, often migrating between feeding and breeding grounds. They are known for their deep, resonant calls, which can be heard over long distances underwater. Despite their size, blue whales are gentle giants and pose no threat to humans.