The Class Merostomata is comprised of horseshoe crabs. These organisms are not true crabs. They are chelicerates which means they have six pairs of appendages and one pair is used for feeding. Their bodies are divided into three regions: the cephalothorax, the abdomen, and the telson. The cephalothorax is composed of a fused head and thorax. The abdomen is the body region of an animal that corresponds to the belly. The telson is a long spike used to steer and defend. Horseshoe crabs are scavengers that primarily scavengers that usually feed at night on worms, molluscs, or other organisms.