Interdisciplinary research on hemichordate evolution

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Where do we come from? What is our ancestry? My research program is focused on evolution of the deuterostomes, that major division of the animal tree of life that includes the vertebrates (and man). Deuterostomes consist of three major phyla: the echinoderms (sea urchins, sea cucumbers and their cousins), hemichordates (acorn worms and pterobranchs) and chordates (including the vertebrates). My greatest interest is in deep events within deuterostome evolution, including the question - what was the nature of the basal deuterostome? My studies have suggested that the ancestral deuterostome may have resembled an enteropneust hemichordate worm. My research program uses a multidiscipinary approach, including organismal and molecular biology, fluid mechanics, and paleontology to test this hypothesis. Over the next five years there are four areas where my research will be applied to evaluate the hypothesis of an enteropneust-like basal deuterostome. First the biominerals we recently discovered in enteropneusts could be an ancient character and at some levels appear homologous to the biomineral skeleton of the echinoderms. Second, the hemichordate pterobranchs, with their unique tentacular feeding arms would represent a derived condition from a pharyngeal filter-feeding ancestor. The evolutionary pressure for such modification may relate to fluid dynamics in relation to organismal size (pterobranchs are small organisms). Third, it is plausible that the pre-oral structures of hemichordates (pre-oral ciliary band of enteropneusts and red band of pterobranchs) could be homologous with the vertebrate adenohypophysis, the anterior pituitary region that regulates stress, growth, and reproduction. Fourth, we will demonstrate that acorn worms are an ancient group, with fossils first appearing in the Cambrian period - pushing back their fossil record nearly 300 million years! This research will advance our basic knowledge of our evolutionary history. Moreover, techniques and tools developed will advance the field of fluid mechanics, including it's application to biological systems.