Many animals have eyes that rest in bony sockets, or open circles of bone that support the eyes. These sockets secure the muscles that hold the eyes in place and help the eyes move. Frogs lack these bony sockets. Instead, a frog has a thin membrane separating his eyes from the top of his mouth. The membrane is strong enough to hold his eyes in place, but flexible enough to arch downward into the mouth as needed. This membrane is what touches the food -- not the eyes themselves.