How do emperor penguins swim?

Answer 1

Emperor Penguins rely on their wings to propel them through water. They have small wings which are much more useful underwater because they have lower drag and greater agility. Their wing bones are fused straight, rather than angled like a flying bird's, and this has the effect of making the wing rigid and powerful, like a flipper. The small wings and a streamlined body shape are ideal for diving in water. They have webbed feet to give them greater speed, while their body shape is also streamlined for rapid swimming and effective diving. The streamlining effect is enhanced by the fact that their feathers are specially shaped to overlap.

Although not built for flying, what Emperor penguins (and other species of penguins) effectively do is to 'fly' underwater. Unlike flighted birds which have hollow bones, they have solid bones, which can stand up to the stresses of underwater swimming, diving and hunting. Penguins also have higher levels of myoglobin which helps them to swim. Myoglobin is the main way penguins store oxygen during their long dives. The difference between Emperor penguins and flying birds is that the muscles of flying birds are filled with mitochondria and enzymes to power flight, and there is no space left-over for myoglobin. So, flying birds cannot spend us much time underwater as penguins because they have less myoglobin (less oxygen per body mass) and lower body mass (less over oxygen).