ocr: FLIGHTLESS BIRDS Plumage WATERPROOF PENGUIN'S feathers divide SURFACE Aa at their base into two quite different parts. One is hard and stiff, and the other soft and downy. The hard parts overlap to form a smooth, waterproof surface. The soft parts lie under this covering, and help keep the bird warm. Beneath their skin, penguins often have a layer of fat called blubber. This works with the feathers to help conserve body heat. DENSE, OVERLAPPING FEATHERS
