Meeting Abstract

P1.126  Jan. 4  Evaluating the phylogenetic significance of nematocyst ultrastructure for Cnidaria REFT, AJ; Ohio State Univ., Columbus ajreft@hotmail.com

Nematocyst, intracellular capsules important for the capture of prey, defense against predators, and intraspecific aggression, are found in all cnidarians. Nematocysts vary in morphology, with more than 30 types currently recognized. However, because variation in nematocyst morphology has not been carefully studied, the distribution of the various morphological attributes of nematocysts and the homoplasy in these features is poorly understood. To better understand its phylogenetic significance, I documented the variation in one aspect of nematocyst morphology: the covering of the apical opening. I found that within Actiniaria (sea anemones), at least some elements of ultrastructural morphology are consistent within a particular taxon, regardless of the type of nematocyst, suggesting that nematocysts that are classified as the same type may not be homologous or that diversification of these types occurred in some taxa.