The Development and Neuronal Complexity of Bipinnaria Larvae of the Sea Star <i>Asterias rubens</i>

Synopsis Free-swimming planktonic larvae are a key stage in the development of many marine phyla, and studies these organisms have contributed to our understanding major genetic evolutionary processes. Although transitory, often attain remarkable degree tissue complexity, with well-defined musculature nervous systems. Among best studied belonging phylum Echinodermata, but work largely focused on pluteus sea urchins (class Echinoidea). The greatest diversity larval strategies among echinoderms is found class Asteroidea (sea stars), that rapidly emerging as experimental systems for developmental studies. However, bipinnaria stars only been detail small number species although they relatively well described neuro-anatomically, poorly understood neurochemically. Here, we analyzed embryonic anatomy common North Atlantic star Asterias rubens, using variety staining methods combination confocal microscopy. Importantly, chemical complexity system was revealed through use diverse set antibodies, identification at least three centers differing neurochemical signature within previously system: anterior apical organ, oral region, ciliary bands. Furthermore, sites cell division analyzed. Comparisons progression molecular across Echinodermata provided basis hypotheses shared processes shaped this group animals. We conclude appear be remarkably conserved ∼200 million years time may represent strong and/or constraint utilizing strategy.