Meeting Abstract
As sister group to Bilateria, Cnidaria provides the opportunity to better understand the evolution of the body plan shared by nearly all metazoans. Extensive work on the anthozoan Nematostella and hydrozoans Hydra and Hydractinia has helped us understand the molecular and developmental programs underpinning the cnidarian body plan. Comparatively little is known about molecular and morphological development within the cnidarian class Scyphozoa, which will provide a fuller view of cnidarian development and evolution and, by extension, a fuller view of metazoan evolution overall. Cassiopea xamachana serves as a useful scyphozoan representative for studying development: fertilized eggs and embryos can be collected daily from gravid females, and the full life history can be completed in laboratory conditions. Furthermore, Cassiopea reproduces both sexually and asexually, allowing comparison between both modes. To investigate molecular developmental controls, we first describe normal morphology during embryonic development and asexual reproduction, determining that asexual propagules generally retain the polyp identity of tissues rather than recapitulating embryonic development. However, it remains unclear the extent to which molecular signals controlling embryonic development are active during the morphologically distinct asexual reproduction process. To answer this question, we use in situ hybridization to compare expression of known developmental patterning genes in both embryos and asexual propagules of Cassiopea.
