bodies are fusiform in shape, tapered at each end and very hydrodynamic.
Studies have shown the penguin form to be the most hydrodynamic
of all marine creatures, meaning they need to use less energy to
dive. They fly in the water by the up and down movement of their
wings (shaped like paddles), with both the up and down stroke providing
power. In flighted birds, power is exerted only on the down stroke.
Penguins float on the surface of the water but do not use their
feet to paddle like ducks and other water fowl.