The arthropod group is separated into 4 groups, Insecta, Crustaceans, Myriapods, and Arachnids. They have an exoskeleton and jointed appendages. They do have to molt to grow because of their exoskeleton. After they molt they're open and weak to predators. For digestion, arthropods have a mouth and anus. Also, they reproduce sexually. Arthropods have bilateral symmetry. -bw