Cetaceans

 are marine Mammals. They live underwater, but like all mammals, they breath through lungs. The largest Animal in the world, the Blue Whale, is a Cetacean. Along with whales, dolphins and porpoise are Cetaceans as well.

Facts

 * Dolphins are some of the smartest animals.
 * The largest animals in the world are Whales.
 * Although Cetaceans seem hairless, they have a small bit of hair.
 * Cetaceans have large brains in comparison to their bodies.
 * Sperm whales have the largest brains in the world.