Imagine if you only had to eat a single meal in your lifetime. For Elysia chlorotica slugs, this is a reality.
This animal innovator feeds on chlorophyll containing algae, isolates the chloroplasts–which produce the chlorophyll necessary for photosynthesis–and then genetically integrates the organelles into its own cells. Biologists have shown that "once a young slug has slurped its first chloroplast meal from one of its few favored species of Vaucheria algae, the slug does not have to eat again for the rest of its life. All it has to do is sunbathe."
However, there is still some skepticism as to whether or not the sea slugs are actually producing new chlorophyll pigments or just using a stored supply from their algal origins. Sidney K. Pierce, from the University of South Florida in Tampa, experiemented with Elysia and confirmed that they were in fact producing new chlorophyll independently–and therefore photosynthesizing–using the borrowed organelles. This is an unprecendented evolutionary achievement. Pierce's work is set to be published in the journal Symbiosis in the near future.