An average adult American alligator's weight and length is 790 lb. and 13.1 ft., but they sometimes grow to14 ft. long and weigh over 450 kg 990 lb. The largest ever recorded, found in Louisiana, measured 19.2 ft.
Adult alligators are black or dark olive-brown with white undersides, while juveniles have strongly contrasting white or yellow marks which fade with age]
No average lifespan for an alligator has been measured.