Eastern Emerald Elysia

The eastern emerald elysia is a specie of sea slug that is found along the eastern coast of the U.S and only eats algae, it has been known for a long time that the Eastern Emerald Elysia had a special relationship with the algae but it has only been recently discovered that the Eastern Emerald Elysia uses the algae's genes for photosynthesis.
The sea slug eats the algae to absorb it's chloroplasts (the cells that do the photosynthesizing) but in order to do this the chloroplasts need a whole new set of specialized cells, but the slug can lift genes from the algae which allows the slug to make the Proteins it's self. The slugs also pass on the genes to its offspring and they only need to eat for two weeks of the year and the other fifty they're just soaking in the rays.