The largest animal that has ever lived on Earth is the blue whale (*Balaenoptera musculus*). These magnificent marine mammals can reach lengths of up to 100 feet (30 meters) and can weigh as much as 200 tons or more. Blue whales are filter feeders, primarily consuming tiny shrimp-like animals known as krill. They are found in all the world's oceans, though their populations have been significantly reduced due to whaling activities in the 20th century. Conservation efforts continue to help protect blue whales and their habitats, as they play a crucial role in ocean ecosystems.