Distinguished by a bright red-orange bill and white eye patches, the Emperor Penguin (Aptenodytes forsteri) is the largest of seventeen penguin species, the deepest diver of any bird and the only animal to winter in Antarctica's open ice. In order to survive the biting cold, Emperor penguins are equipped with several layers of scale-like feathers. They are also very social creatures, which huddle together to conserve warmth. Female Emperors lay a single egg in autumn before heading out to sea to hunt krill and squid. Depending on the extent of the ice pack, they may be forced to trek long distances in order to reach the ocean. During the separation, males envelop the egg in a brood pouch above their feet. Each penguin spends time in the middle of the huddle to stay warm, but accepts when it is time to move to the perimeter. By the time the eggs hatch, the male Emperors have not eaten for several months. When the females return with food for their chicks, hungry fathers head to sea. From then on both parents attend to the young. In summer, when the ice around the breeding colony breaks up, the young learn to swim and fish by themselves.