The moray eels, like this goldentail moray (Gymnothorax minliaris), are often feared because of their continuous motion of opening and closing their mouths. In fact, they must do this in order to breathe. Eels are nocturnal animals and stay mostly to themselves, hiding in the reef crevices during the day. They will protect their home from intruders, though, and with their poor eyesight they can easily mistake a taunting human hand in their cave openings for a fish. (photo: Steve Kipnis - Florida Keys NMS)