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….For the longest time, the debate over the color green in the animal kingdom has been dominated by a singular character. While Kermit sang the first shot across the bow in the debate over green, a team of scientists led by Professor Sidney K. Pierce may have finally found a worthy adversary. Meet Elysia chlorotica, the green sea slug which may change the way we think about the line between plants and animals and the merits of being green.
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….What makes Elysia choloritica organisms special is that scientists have discovered that not only do they contain chloroplasts which they can then use for photosynthesis but that their acquisition of those chloroplasts may also have given them their own photosynthesis supporting genes. Elysia choloritica first obtains the chloroplasts (and turns itself from brown to green) by sucking them out from the interior of Vaucheria litorea, a specific type of algae that they feed on. Scientists had already known that they then retain the chloroplasts and use them to produce sugars while sunbathing! However using radioactive tracing scientists were finally able to discover how they were able to maintain the chloroplasts for extended periods of time (up to 8 months) without ingesting any new material from algae. It turns out that Elysia choloritica actually had its own photosynthesis supporting genes and even more amazingly that those genes were even in its egg and sex cells!
….The mechanism of acquisition of those genes by Elysia choloritica from the algae is believed to be Horizontal Gene Transfer. Horizontal Gene Transfer is a mechanism whereby an organism acquires new genetic material from other organisms by means other than descent. In this case the slug borrowed algal genes needed in the photosynthesis process just by consumption of the algae. Besides highlighting a new selling point in the perpetual marketing campaign waged to get kids to eat their vegetables, such a discovery also may mean that evolution was more complicated than ever imagined. Hybrid plant-animals or links between the two may suddenly be viable evolutionary pathways. In any event, Elysia choloritica’s decision to go green clearly has been a great boon to its ability to feed itself and presents a very convincing rebuttal to Kermit’s salvo against the color.
Mad Science @ QHST 