Anything you can do, slugs can do better.

I’ve always loved gastropods. When I was a child I would rescue snails from the wrath of gardeners. After sticking numbers on their shells I released them back into the “wild”. Of course, I did this only after I had made notes and measurements of their coloration, size and behavior. Then I would regularly sweep the garden to re-capture the snails by checking at the base of iris plants, inside discarded pottery, and underneath the wide squash leaves. Any snail that had a numbered shell would be spared the wrath of my parents (they assured me) when they were doing the weeding. As the snails would turn up again I would keep track of them by their numbers—I suppose I was a budding researcher. If you didn’t know me it would seem odd that I am going into law.

Anyway, I think the most popular group of these soft-bodied wonders are the nudibranch. Colloquially they are called “sea slugs”, though that classification isn’t perfect, as there are several other groups apart from the nudibranch that are called sea slugs. The nudibranches are usually brightly colored, often toxic, and often have a beautiful frond-like appearance. They are like flamboyant ghosts that glide along the sea bottom, eating as they go. But all species of “sea slug”, are fascinating. One in particular—Elysia chlorotica—takes fascinating to the next level.

Elysia chlorotica (a beautiful name, really) is a photosynthetic animal. Quite an uncommon thing in the animal world, but an admirable one. Sea slugs support several species that utilize the sunlight in some way to get energy—usually by using the chloroplasts of the algae they ingest in some form. Studies done on E. chlorotica show that it does “steal” the chloroplasts, lining its gut cells with them. Chloroplasts, similar in some ways to an animal cell’s mitochondria, are the power-houses of the plant cell. They can take light-energy and convert it to sugar-energy. What’s interesting is that the chloroplasts alone do not have the genetic information to complete photosynthesis—the DNA for that resides in the nucleus of the plant cell. Scientists knew that E. chlorotica was using photosynthesis, so it must have some kind of genetic means to. When they looked further they found that the algae DNA for photosynthesis had been incorporated into the slug’s own DNA, allowing the proper proteins to be made to keep the chloroplast factories working.

There is no clear evidence on how E. chlorotica incorporates DNA from its food into its own cells—it’s a process undescribed by human science. DNA can jump between species—we’ve seen it before—but this slug’s ability to make the alien DNA function, and use it for some clear means, is unique. Some other animals can use sunlight for energy, but always by using the entire plant cell, not just the relevant stolen DNA. They can make the proteins required to keep converting sunlight to energy.

And what are the implications? My first thought is that I would love to be a green-skinned person. I wouldn’t want to give up my ability to ingest food (and as a warm-blooded animal with high energy demands, that would be ill-advised), but if I could use photosynthesis to my advantage I would be thrilled. No more blood sugar crashes as long as I can go outside. My pale, easily-burned skin would be replaced by a nice organic shade of green.

Or, getting into the hot-topic of genetically modified food, what about chickens that have plant-derived protein? You could eat a fried egg and get plant nutrients. As cattle graze, they could be getting even fatter on energy derived from the sun.

These discoveries were all very recent. For me the message is clear—there is so much Earth has to offer us still as far as knowledge and relevant life processes. We are still discovering new species every month; new species that could potentially hold keys to our own biology, or the environmental crisis we are facing. Ironically, our destruction of areas whose diversity we can only guess at is also annihilating species as amazing as E. chlorotica.

Forget the awesome potential for green skin—what if we’re killing off the species that will help us cure cancer? Or develop technologies to re-grow appendages? Or provide nutrients to third-world countries at a nominal cost? Considering how many species we lose each month we probably are killing off species that could lead us to such things. We could be changing a whole host of miserable social issues if we only put protecting the world we must share as our first priority.

Recently in the news it has been noted that human kind is the leading cause of the greatest mass-extinction Earth has ever experienced. Save the Earth. If not for the potential to photosynthesize lunch as you hang out on the beach, do it because you’re a selfish bastard and care only about human welfare.

Check out this and this for more information on "solar-powered sea slugs".