My goal during the Grass Fellowship is to establish the foundation for investigating the development, fusion, and physiology of the ctenophore subepithelial nerve net towards understanding early nervous system evolution. To establish this foundation, I will establish a system for studying the molecular mechanisms underlying the fusion of neurons in the SNN of the ctenophore M. leidyi. M. leidyi was selected because it is a widely studied model species. Its genome has been sequenced; an embryonic fate map has been generated; the ultrastructure of its SNN has been characterized; gene editing tools have begun to be developed, and the animal is readily available at Woods Hole. The first aim seeks to establish a developmental timeline for when SNN neurons fuse, and the second aim seeks to interrogate expression of synapse-associated genes that may play a role in fusion.