When a crocodile loses a tooth, it is quickly replaced. These reptiles can go through 8,000 teeth over a lifetime. Crocodiles are often confused with alligators, but there are some easy-to-spot differences. An alligator's jaw is U-shaped, while a crocodile has a V-shaped jaw, according to the San Diego Zoo. Crocodiles also have teeth that stick up over their upper lip when their mouths are closed.