Ahh the wonders of Stumbleupon! After a very unproductive Saturday afternoon, I found this wonderful little creature, Elysia chlorotica. I learned that after just two weeks of algae meals as a young slug, E. chlorotica can survive for the rest of its life (about one year) by getting energy only from photosynthesis. Unlike other animals that benefit from photosynthesis, this sea slug doesn’t take in the whole photosynthetic organism and exploit it. It only needs the chloroplasts. These chloroplasts, however, normally could not survive alone inside animal cells. To solve this problem, this slug managed to sneak at least one of the algae’s photosynthesis genes somewhere along the way, as well. This kind of horizontal gene transfer is pretty rare in multicellular organisms, so it’s a very interesting example, indeed.
Another photosynthetic animal worth noting is Ambystoma maculatum, a salamander that holds photosynthetic algae within its cells. While photosynthetic organisms can often reside in invertebrates, the spotted salamander is the first vertebrate known to do this. An article in Nature demonstrated that the algae that reside within the salamanders’ cells may actually be passed vertically from the mother, as well as taken in from the environment. The symbiotic relationship here is much closer than expected.
These are two distinctly interesting animals that use photosynthesis, but there are bound to be many more out there just waiting to be noticed. These organisms can give great insight on the developments of close symbiotic relationships, something that we symbiont researchers are always interested in!