Cloning in Response to Predation in Several Echinoderm Species

Marine invertebrates have many ways of reacting to predators, including the recently discovered response of larval cloning. Larvae of the sand dollar Dendraster excentricus have been observed to clone themselves in the presence of fish mucous. So far, this response to predator cues has only been observed in one species, but several other species of echinoderms are known to clone their larvae in response to fluctuations in food. In this study we examined how widespread larval cloning as a response to predators is among echinoderms. Larvae of three echinoderm species (the sea urchin Lytechinus variegatus, and the sand dollars, Echinarachnius parma and Dendraster excentricus) were reared to the 4-armed plutei stage in the lab when individual larvae were exposed to several predator treatments: mucus of the mummichog ( Fundulus heteroclitus), mummichog odor water, and  filtered seawater as a control. For D. excentricus experiments, we also exposed the larvae to two components of fish mucous (heparin and chondroitin). Larvae were examined daily for clones or budding structures on larvae that would indicate cloning. We expect E. parma is more likely to clone since it is more closely related to D. exentricus than L. variegatus is. Results of this study will provide information on the evolution of larval cloning as a response to predators.