A shark can lose up to thirty thousand teeth over a lifetime. A thirty-foot prehistoric crocodile is believed to have had the greatest bite force of any animal-past or present. A six-foot Gaboon viper can have fangs up to two inches in length, with the ability to deliver enough venom to kill thirty full-grown adult humans. When not in use, the hinged fangs can be folded up against the roof of the mouth. The giant armadillo has the most teeth of any land mammal with 74, while the spinner dolphin is the toothiest of all mammals, with up to 260 sharp, pointed teeth filling its long, skinny jaw. Fang blennies, tiny reef fish, are sometimes swallowed whole by larger species. Once inside the mouth, they use their fangs to put a narcotic-laden bite on the predator who falls into an open-mouthed trance, allowing the fang blenny to escape. By the time George Washington became president in 1789, he had only one of his own teeth, and his false teeth were definitely not made of wood. Eighteenth-century dentures were commonly constructed with teeth from cows, horses, walruses, elephants, and hippos. Human teeth were also used. Venom from a South American pit viper was used to develop captopril-one of the most important drugs used to treat high blood pressure.