The genus Heloderma, has 5 members, the Gila monster and 4 beaded lizards, Gila monsters are large, stocky, most of the time slow-moving reptiles that prefer arid deserts. Beaded lizards are seen to be more agile and seem to prefer more humid sourroundings. Their tails are used as fat storage organs. The scales of their head , back and tail are looking bead-like, containing osteoderms for better protection. The scales on the belly side are free from osteoderms. Most species are dark in color, with yellowish or pinkish markings. "Heloderma" is the only living genus of the family Helodermatidae.