Mammals are a class of animals that are warm-blooded, have hair, and produce milk for their young. Apes are a type of mammal that includes humans, chimpanzees, gorillas, and orangutans. Whales are a type of mammal that live in the ocean and include dolphins, porpoises, and blue whales. Frogs are a type of amphibian that are cold-blooded, have smooth skin, and lay eggs in water.