CURTIS, N/E; MASSEY, S/E; SCHWARTZ, J/A; TAGIHOF, H; PIERCE, S/K; University of South Florida: The intracellular, functional chloroplasts in adult Elysia crispata come from several algal species, and are different from those in juvenile slugs.

The sacoglossan sea slug, Elysia crispata, sequesters chloroplasts from its algal food source within specialized cells lining the digestive diverticulum. These stolen chloroplasts photosynthesize within the slug�s cells as long as four months–one of the longest kleptoplastic associations known. While many other sacoglossan species feed on and sequester chloroplasts from only one species of algae, we have previously shown that field collected, adult E. crispata sequester plastids from three different species of algae; Penicillus capitatus, Halimeda incrassata, and Halimeda monile. We have now done feeding experiments testing the ability of newly-metamorphosed, juvenile E. crispata, raised from egg masses in the lab, to sequester chloroplasts from multiple algal species using a large range of potential algal food sources. Surprisingly, juvenile E. crispata fed on different algal species (Bryopsis plumosa and Derbesia tennissima) from the algae we found in the field collected adults. Transmission electron microscopy verified that the B. plumosa and D. tennissima chloroplasts were sequestered intracellularly in the juvenile slugs. In addition, juvenile E. crispata fed exclusively on Bryopsis plumosa could be grown to adult size, and, as adults, they would switch to feeding on Penicillus capitatus if presented with it. Finally, adult slugs fed on B. plumosa were capable of photosynthesis comparable to field collected adults, as monitored by oxygen production, and maintained chloroplasts for approximately as long as the field-collected animals. (NSF grant # IBN 0315227)