Terns are relatively small seabirds that nest and live mostly near coastal areas, though some terns venture inland to lakes. They feed on small fish, often by diving on them and plunging into the water to catch prey in their beaks. The black skimmer is related to the terns, but has its own peculiar way of feeding. The skimmer's lower mandible is considerably longer than the upper mandible. It takes advantage of this by flying low over the water with it beak open, the lower mandible extended into the water. When the bird senses that the lower mandible has struck a fish, it scoops it up and quickly swallows it.