The Phoneutria is one of, if not the deadliest tarantula known. It has a legspan of about 15 centimeters and delivers a very painful and powerful bite. It is a very distinct colored spider and is one to be afraid of. Although it may be highly dangerous, its venom is very important for medical. If the spider sees a potential predator, it stands up on its back legs and raises its front, ready to attack and kill.