The tarantula is an arachnid. An arachnid has 2 body parts and 8 legs. The Goliath birdeater tarantula is considered the "queen of the jungle" because it can be the size of a person's face, can weigh as much as five mice and it is an awesome predator. Sam Marshall is an arachnologist, a scientist that studies spiders. The tarantula has an exoskeleton, or a skeleton on the outside. This skeleton does not grow with the body. As a result, the tarantula must shed, or molt and grow an new skeleton.