9. Fer-de-lance

A bite from a fer-de-lance (Bothrops asper) can turn a person's body tissue black as it begins to die, according to a 1984 paper published in the journal Toxicon. These pit vipers, which live in Central and South America and are between 3.9 and 8.2 feet (1.2 and 2.5 m) long and weigh up to 13 pounds (6 kg), are responsible for about half of all snakebite venom poisonings in Central America, according to a 2001 study published in the journal Toxicon.