The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, probing for food, courtship and feeding young. The term also refers to a similar mouthpart in some monotremes, cephalopods, cetaceans, pufferfishes, turtles, Anuran tadpoles and sirens. Anatomy Beaks vary significantly in size and shape from species to species. The beak is composed of an upper jaw, called the maxilla, and a… (More on Beak)