No, and among the flightless birds, the penguins and the ratites are the best known. Ratites include emus, kiwis, ostriches, rheas, and cassowaries—they are called ratites because they lack a keel on the breastbone. On the other hand, although penguins cannot fly, they really don’t need to, because some types, such as the Adelie, can reach the remarkable speeds of 40 to 100 miles (64–161 kilometers) per hour in the oceans, outswimming some smaller and larger fish. All of these birds have wings but lost their power to fly millions of years ago. Many birds that live isolated on oceanic islands, such as the great auk, apparently became flightless in the absence of predators because they never needed their wings to escape.