In the rose haired tarantula, the body is divided into two segments, the cephalothorax (a fused head and thorax) and the abdomen. The cephalothorax contains the mouthparts, the eyes and the legs. The abdomen contains the reproductive structures and the silk-producing structures. Almost all spiders breathe through organs known as book lungs. These are hollow leaf-like structures through which the blood flows, so that the blood can acquire oxygen to be distributed thoughout the body. The opening to the book lungs is located below the abdomen. All arachnids have piercing mouthparts called chelicerae. In spiders, the chelicerae are modified into fangs. At the base of the fangs are poison sacs that are used to subdue prey. The bite of the tarantula is not very painful or dangerous to humans, unless one has a severe allergy. A fully mature Rose Hair can reach approximately 5 inches (12.5 cm) with legs extended. They have a brown body, but the cephalothorax is colored a slight metallic pink, giving them their name. One way they protect themselves is by flicking abdominal hairs at the attacker. These hairs can irritate the skin, eyes and nose.