weighs as much as 20 elephants but lives beneath the sea. The blue is Earth's largest animal. Larger than the largest of ancient dinosaurs, blue s can grow to be more than 100 feet (30 meters) long and weigh nearly 150 tons. Not all s are so large. The much smaller pilot grows to about 28 feet (8.5 meters) in length. And dolphins, which belong to the family, range only from 3 to 13 feet (1 to 4 meters). Although s spend their lives in the sea, they are, like humans, warm-blooded mammals. After a baby is born, it nurses on its mother's mil ....