flight sustained, self-powered motion through the air, as accomplished by an animal, aircraft, or rocket. Animal Flight Adaptation for flight is highly developed in birds and insects . The bat is the only mammal that accomplishes true flight; flying squirrels glide rather than fly, as do flying fish and flying lizards. Birds fly by means of the predominantly up-and-down motion of their wings. The flapping motion is not, however, straight up and down but semicircular, the wings generally moving backward on the upstroke and forward on the downstroke. That motion pushes... Read more