Why do copperhead snakes have scales over their eyes? — Michael of Croton-on-Hudson, NY

Dear Michael,

All snakes have scales over their eyes. They need these scales for protection, since they don't have eyelids. At certain times, however, a snake's eyes become cloudy. Do you know why?

As a snake grows, its skin doesn't. It must shed its old skin; this is called "molting." A snake's skin is in one piece — like a glove that covers its body from head to tail. Before molting, a new layer of skin forms beneath the old one. Then a liquid spreads between the old and new skin which helps separate them. This liquid causes the snake's eyes to become cloudy. When the old skin comes off, its eyes clear up again.