ABSTRACT
Echinoderm nervous systems have been the subject of research and debate for many years. Much of the attention has been on typical echinoderm features including pentaradial organization in the adult compared to bilateral organization in the larva. Further focus has emphasized the variety of organization in the echinoderm clades together with the amazing regenerative capacity in both adults and larvae. Here we review current thinking on adult echinoderm nervous systems and attempt to identify common themes and practices. In particular we present evidence for the role of shared cellular and genetic pathways that regulate adult regeneration. Recent evidence from crinoids and now from ophiuroids indicates that BMP homologues are present in both taxa and appear to be closely related to the BMP2/4 and BMP5/7 classes. Expression studies suggest that in both crinoids and ophiuroids, BMPs are important components of the regenerative process and perhaps indicate a common, shared, mechanism. New electrophysiological and behavioural evidence from Asteroids has also begun to identify putative novel mechanisms involved in functional recovery during arm regeneration.
