Asked by: Sally Thompson, Burnley
Even the very smallest penguin, the fairy penguin, weighs 1kg, which is about as much as a herring gull. But herring gulls have a 1.4m wingspan, compared with just 32cm for the fairy penguin. Water is 784 times denser than air, and around 62 million years ago, penguins began evolving adaptations for swimming underwater. Their bones are filled with heavy bone marrow rather than air and they have much larger stomachs for undergoing long fishing trips away from the nest.