The world's largest mammal is the blue whale. These magnificent creatures can grow up to 100 feet long and weigh as much as 200 tons or more. Blue whales are found in oceans around the world, primarily in deep waters. They are filter feeders, primarily consuming tiny shrimp-like animals called krill, which they consume in massive amounts during feeding seasons. Blue whales are known for their incredible vocalizations, which can be heard over great distances underwater, and they are a symbol of marine conservation efforts, as their populations have been severely impacted by whaling in the past.