Physical description
All penguins have a white belly and a dark (mostly black) back. Penguins cannot fly, but they can swim very well. Their wings have become stiff and small swimming flippers. They have good hearing and can see underwater. The white and black colors are for camouflage (to help them hide) when they swim. So, when a predator looking from underwater sees the white belly and wings of the penguin, they can not see it well with the light coming from above. Seen from above, the penguin's black back blends in with the dark water.
The biggest penguins may stand nearly 4 feet tall (110 cm) and can weigh almost 100 pounds (40 kg). The smallest kinds are only about one foot (32 cm) tall. Penguins have a thick layer of blubber that helps them keep warm, and their feathers are very tightly packed to make another cover. They also have a layer of woolly down under the feathers that are coated with a type of oil that makes them waterproof.