The Museum of Zoology includes six divisions, each with two curators: mammals, birds, amphibians and reptiles, fishes, insects and other arthropods, and mollusks. World-wide, these groups include several million species. The divisional collections include some 15 million specimens: 4-6 million insects; 5.5 million mollusks, 3.5 million fishes, 355,988 amphibians and reptiles, 200,000 birds, and 130,000 mammals. All of the divisional collections are ranked among the most extensive and important in the world. The Museum also operates multi-user laboratories in cytogenetics and molecular systematics.