Functional Morphology and Diversity: Volume ICrustaceans are increasingly used as model organisms in all fields of biology, including neurobiology, developmental biology, animal physiology, evolutionary ecology, biogeography, and resource management. One reason for the increasing use of crustacean examples is the wide range of phenotypes found in this group and the diversity of environments they inhabit; few other taxa exhibit such a variety of body shapes and adaptations to particular habitats