Whales: Giants of the Ocean Whales are among the largest and most remarkable animals on Earth. These marine mammals live in oceans around the world, from warm tropical waters to the cold seas surrounding the poles. Life Beneath the Surface Although whales spend their lives in water, they breathe air through blowholes located on top of their heads. They must regularly return to the surface to breathe before diving again in search of food or traveling through the ocean. Whales are warm-blooded, give birth to live young, and nurse their calves with milk. A thick layer of fat called blubber helps protect them from cold water and stores energy during long migrations. Two Main Groups Whales are generally divided into baleen whales and toothed whales. Baleen whales filter small animals from the water using flexible plates inside their mouths. This group includes blue whales, humpback whales, and gray whales. Toothed whales use teeth to catch fish, squid, and other prey. Many of them also use