Meeting Abstract

128.2  Tuesday, Jan. 7 13:45  Development and life cycle evolution in the sea nettle jellies (Pelagiidae) HELM, RR*; DUNN, CW; Brown University rebecca.rae.helm@gmail.com

Life cycle evolution is difficult to study because many instances of life cycle transition occur at the base of diverse lineages. One exception is the mauve stinger jelly Pelagia noctiluca, which has evolved direct development, despite being nested within a clade of indirect developing species. There are three possible ways that P. noctiluca has achieved this: 1. a heterochronic shift to develop jellyfish (termed medusae) prematurely, thus skipping the intermediate polyp stage, 2. by incorporating a pelagic, reduced polyp stage in development or 3. through novel developmental mechanisms for developing medusae. To investigate these alternate hypotheses, I examined morphological development of P. noctiluca and its indirect developing sister species Chrysaora fuscescens. Here I present my findings, focusing particularly on muscle development, and their implications for understanding life cycle evolution in this clade.