"Members of the auk family, such as these guillemots and puffins... propel themselves, not with their feet like ducks, but with their wings, and they have paid a considerable price to be able to do so... Auks have had to evolve shorter, stubbier wings. That gives them a rather clumsy, whirring flight in the air, but it does enable them to "fly" underwater so well that they can outpace small fish."