We study the cellular and molecular mechanisms underlying animal development, and how these mechanisms can influence evolutionary change. We focus on embryos of molluscs and related animals, because of their large accessible cells, invariant cleavage patterns, informative phylogenetic position in the animal kingdom, and (of course!) their intrinsic beauty. Molluscs are representatives of a large clade of protostome phyla--the Lophotrochozoa--where molecular mechanisms of development are poorly understood. In addition, molluscs typify spiral cleavage, a dominant mode of early development in multiple protostome phyla and a developmental trait with an interesting evolutionary history. These embryos are amenable to a variety of classical embryological manipulations, allowing functional tests of hypotheses about patterning mechanisms. We are pursuing questions about several aspects of early patterning in the snail Ilyanassa, from the mechanisms of asymmetric cell division to signaling by the molluscan embryonic organizer. Our findings are providing new insights into the diversity of developmental mechanisms found in animals, as well as a clearer picture of how such processes evolve. Interests: The evolution of developmental mechanisms; Early patterning in molluscs and related groups; Cytoskeletal basis of asymmetric cell divisions; Evolution of novel phenotypes