This is actually a very important form of camouflage called countershading. It is found in many open ocean animals. If a puffin were sitting in the water and a predator flew over it, the black back feathers would blend in with the water, which appears dark from above. Or if a shark were swimming beneath it, and looked up, the white belly of the bird would blend in with t he sunlight above the water. So puffins, penguins and many other open ocean animals are camouflaged from above and from below.
Puffins belong to the family of seabirds known as alcids or auks.
Close relatives include razorbills and guillemots. There are two other types of puffins in existence, the horned puff in and the tufted puffin. While common puffins only live in the Atlantic Ocean, tufted and horned puffins live in the Pacific Ocean. Like all seabirds, alcids have several adaptations which enable them to survive in the cold ocean water. Besides being countershaded, puffins have a thick coat of small feathers called down under their dense top feathers.