12: Alligator Gar
This fearsome fish is a relic of the dinosaur age, dating back some 100 million years and growing to over eight feet in length. Their reptile-like snouts house rows of sharp teeth and an adaptation allows this fish to actually breathe air. Though intimidating in size and weaponry, alligator gar are docile creatures that can be found peacefully swimming freshwater rivers and lakes from the Rio Grande to the Missouri River.