Epithelial conduction: recent findings, old questions, and where do we go from here?

Issue Title: Coelenterate Biology 2003: Trends in Research on Cnidaria and Ctenophora, Proceedings of the 7th International Conference on Coelenterate Biology, held at the University of Kansas, Lawrence, Kansas, U.S.A., 6-11 July 2003 Work on the roles of excitable epithelia in hydromedusan behaviour is reviewed from the historical point of view. Of special interest are cases where epithelial impulses excite or inhibit nerves. It is suggested that nerves running in the endoderm canals as described in several species with excitable endodermal epithelia may function to convey excitation to nerves in the ectoderm, but the precise pathways and mechanisms whereby epithelial depolarizations lead to the generation or suppression of neurally mediated processes are still poorly understood. Recent work on feeding in Aglantha digitaleshows a component (lip-flaring) that may be a version of the crumpling behaviour seen in other medusae. The pathways mediating feeding and crumpling behaviours are reviewed.[PUBLICATION ABSTRACT]