Meeting Abstract
The crustacean stomatogastric nervous system (STNS) requires the input of neuromodulators to enable behavioral flexibility. The pyloric circuit is one of four central pattern generators (CPGs) in the STNS; its outputs control food processing by foregut muscles. The sensitivity of the pyloric circuit to various neuromodulators has previously been examined in two crab species. One species, Cancer borealis, is an opportunistic feeder, while the other, Pugettia producta, is a dietary specialist. Since neuromodulation enables variation in the movements of pyloric muscles without altering STNS circuitry, the modulatory capacity is predicted to reflect the need for diversity of feeding patterns and thus the diversity of diet in each species. In contrast, we predict no relationship between diet and modulatory capacity of other CPGs, such as the cardiac ganglion, which controls the crab heart. Previous data have shown that the Cancer STNS is sensitive to a wider array of neuromodulators than that of Pugettia. However, these species are not closely related phylogenetically. To examine the relationships between diet, phylogeny, and modulatory capacity, we recorded the responses of two members of the same superfamily as Pugettia, the opportunistic-feeding crabs Chionoecetes opilio and Libinia emarginata. The responses of the isolated STNS and whole heart preparations to six endogenous neuromodulators and an acetylcholine agonist were measured. Initial results suggest that, in contrast to Pugettia, the STNSs of the two opportunistic feeders are sensitive to all tested modulators. Preliminary data also suggest that the cardiac ganglia of specialist feeders and opportunistic feeders respond to the same neuromodulators.
