The symbiotic chloroplasts in the sacoglossan Elysia clarki are from several algal species

Abstract. The sacoglossan sea slug Elysia clarki feeds on siphonaceous algae, and intracellularly sequesters chloroplasts, which actively photosynthesize for 4 months. We have determined the algal source of chloroplasts in adults of E. clarki from the Florida Keys, using molecular techniques, feeding experiments, and electron microscopy. Our results clearly demonstrate that specimens of E. clarki sequester chloroplasts from four different species of algae, representing two genera: Penicillus lamourouxii, P. capitatus, Halimeda incrassata , and H. monile. In addition, chloroplasts from more than one species of algae are sequestered simultaneously in the same digestive cell.