Poison dart frog
#5 of 8 most deadly creatures: This frog may look beautiful, but he's a real killer. Known as the poison dart frog, the blue color of this South American creature serves as a warning to would-be predators. Its skin is covered with glands that secrete alkaloid poisons capable of paralyzing and even killing predators. Since the destruction of its rainforest habitat, the blue poison frog has become one of the most threatened of all poison dart frogs.