Meeting Abstract
Ctenophores have recently attracted much attention because several multigenetic molecular analyses proposed Phylum Ctenophora to be the sister taxon to all other animals. The common Western Atlantic ctenophore Mnemiopsis leidyi is currently the object of intense ecological and physiological study. The tentacular apparatus of ctenophores is critical to feeding and very likely bears a diversity of sensory functions. Previous studies of the cydippid Pleurobrachia pileus suggest that the tentacular bulb is an integrative center for afferent signals arising from the distal tentacle and a cell proliferation zone. The tentacular apparatus of adult cydippid and lobate ctenophores are superficially similar but as we show here, are morphologically distinct. Here, we use correlative light and electron microscopy in conjunction with fine extracellular probe recording to demonstrate structure/function relationships within the M. leidyi tentacular bulb. We generated the general scheme of the tentacular apparatus, showing the arrangement of tentilla and tentacular bulb. Bundles of hundreds of tentilla arise from the center of the bulb, indicating the location of the formation of the tentilla. Many tentillae were found connected to the aboral end the tentacular bulb. We created a lesion in the food groove and used time lapse recording to reveal the behavior of the food grove post-incision and tentilla growth path. Based on the histology and TEM, we acquired the scheme of cross section of tentacular bulb with the prediction of function in multiple area of bulb. We also found spontaneous slow trains of robust biphasic action potentials in tentilla where they arise from the aboral end of the tentacular bulb of adult animals.
