Bizarre sea slug is half plant, half animal

Scientists discover chlorophyll-producing sea slug that can carry out photosynthesis using genes swiped from plants.

By

Stephanie Rogers

Thu, Jan 14 2010 at 1:58 PM

186

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Environmental Science, Oceans, Wild Animals

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It looks like any other sea slug, aside from its bright green hue. But the Elysia chlorotica is far from ordinary: it is both a plant and an animal, according to biologists who have been studying the species for two decades.

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Not only does E. chlorotica turn sunlight into energy — something only plants can do — it also appears to have swiped this ability from the algae it consumes.

Native to the salt marshes of New England and Canada, these sea slugs use contraband chlorophyll-producing genes and cell parts called chloroplasts from algae to carry out photosynthesis, says Sidney Pierce, a biologist at the University of South Florida in Tampa.

That genetic material has since been passed down to the next generation, eliminating the need to consume algae for energy.

However, the baby slugs can’t carry out photosynthesis until they’ve stolen their own chloroplasts, which they aren’t yet able to produce on their own, from their first and only meal of algae.

"We collect them and we keep them in aquaria for months," Pierce told LiveScience. "As long as we shine a light on them for 12 hours a day, they can survive [without food]."

Pierce and his colleagues used a radioactive tracer to ensure that the slugs are now producing the chlorophyll themselves and not gathering it from algal contamination in the aquaria.

Crustacean biologist Gary Martin of Occidental College in Los Angeles sums it up in one word: “Bizarre”.

“Steps in evolution can be more creative than I ever imagined,” said Martin.

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Comments: 186

while you were ... Jun 27 2010 at 3:59 PM

It's like a sea slug version of venusaur :o.
"...gets most, if not all, of its energy from the flower on its back. The flower engages in photosynthesis, which provides energy for Venusaur. During this time, it remains completely still. Due to this, it prefers sunny areas and is more powerful in the summertime. It is unknown if Venusaur have to eat at all.

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Hevach Jun 24 2010 at 7:48 AM

"Secondly, plants aren't the only ones who can convert sunlight into chemical energy. A variety of unicellular organisms called phototrophs can also do it." Many corals (which are animals) are photosynthetic, some on their own, some through consumed algae similar to this slug, and some through symbiotic algae. Giant clams and a lot of closely related reef bivalves are photosynthetic. It might sound weird to most people, since most of us are used to animals that walk around and eat each other, but

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photosynthesis is far from alien to the animal kingdom.

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M>A> Jun 23 2010 at 1:32 PM

Skip Pierce ROCKS !!!
King of the Sea Monsters....

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Jessica Jun 23 2010 at 6:34 AM

The last comment makes me sad because the first thing I seem to notice in most heavily read science articles is the author's scientific illiteracy, ranging from poor to just careless. This article is pretty well written, not enough for me to make a point of correcting, but I find it almost disturbing that someone would then defend scientific illiteracy. I am sad because it is shocking today how much scientific illiteracy is prevalent in the news, especially most recently in discussion of the environmental

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affects of the Gulf Cost oil spill, and I appreciate it when others actually can point out mistakes to better educate readers, especially scientific mistakes that when interpreted incorrectly, have much more severe consequences. For example, here we don't fully understand how common and actually primitive this supposedly amazing biological feat is, but elsewhere, scientific illiteracy is the reason why many still believe global warming is not extant due to their inability to understand the discussed processes involved in the crisis. And in consequence, still nothing significant has occurred to reduce carbon emissions, and the topic remains an actual controversy when it should become a legitimate concern. I'm just trying to make people more aware of scientific illiteracy and trying to encourage people to read more critically and understand their own beliefs.

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Guest Jun 23 2010 at 5:04 AM

'a couple of points' i dont know about you but when they talk about algae in biology class, they call it a plant, or a micro-organism. either way, who cares. and rewording. duuuude come ooooooon you obviously understood it correctly, understood it well enough to think you should correct it, so SHUT UP! everyone else will get it too. and did the article ever say that plants are the only things that convert sunlight into personal energy? nooooo. so: yes. nitpicky

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Bo Jul 06 2010 at 10:49 AM

Actually the article does say that plants are the only things that convert sunlight into chemical energy. That's sort of why he quoted it. If you wanna complain about the inaccuracies pointed out in this article and say "nobody cares", you ought to be the one who shuts up. Our knowledge of biology is what keeps you alive today and every bit of it is important.

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Sarah Jun 20 2010 at 2:56 PM

they think it is to do with viral interjection. i think they call it symbiogenesis that the slug has evolved tolerance to the virus and it helps the slug move the chloroplasts from plant to animal. 'Virolution' is a good book to read about this, if anyone's interested!

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MothrNatrRlz Apr 23 2010 at 3:06 PM

"— it also appears to have swiped this ability from the algae it consumes."

It IS Kirby!

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Ryan Apr 23 2010 at 3:03 PM

It's like Kirby

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Daniel Jan 18 2010 at 5:42 AM

"Not only does E. chlorotica turn sunlight into energy — something only plants can do[...]" This could use a bit of rewording... for starters, sunlight already is energy. Chloroplasts convert light energy into chemical energy (ATP), which is a form usable by the organism's metabolic systems. Secondly, plants aren't the only ones who can convert sunlight into chemical energy. A variety of unicellular organisms called phototrophs can also do it. In fact, chloroplasts are thought to have first appeared

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in a primitive (yet still existing) type of bacteria called cyanobacteria, which is also credited with flooding early Earth's atmosphere with oxygen, allowing life as we know it today to exist. Thirdly, a minor point - with the exception of green, red and glaucophyte algae, most algae are not classed as plants. Still, this is more of a taxonomical definition than anything else and isn't really all that relevant to the article. I hope this doesn't sound like nitpicking! Very interesting article!