The largest mammal on Earth is the blue whale (Balaenoptera musculus). Blue whales can grow up to 100 feet long and weigh as much as 200 tons or more, making them the largest creatures to have ever lived on our planet. They are filter feeders, primarily consuming tiny shrimp-like animals called krill, which they gulp in massive amounts. Despite their enormous size, blue whales are known for their gentle nature and typically inhabit oceans around the world. Sadly, they were heavily hunted in the past, and their population has significantly declined, making them a protected species today.