Friday, December 05, 2008

Solar-powered Sea-slugs live like plants

The lowly sea slug, “Elysia chlorotica,” may not seem like the most exciting of creatures, but don’t be fooled: it behaves like a plant and is solar-powered, says a Texas A&M University biologist who has been studying these tiny creatures for the past decade and, along with collaborators from several universities, has identified a possible cause of their ability to behave like plants.

Plants can be compared to solar-powered machines—their cells contain tiny organelles called plastids that trap sunlight and convert it into energy by photosynthesis. The sea slug, however, works a little differently. Its main food source is a specific type of alga. “It makes a cut in the alga, sucks out the cytoplasm [the material inside the alga] and digests most of it. But there’s a twist—it retains the plastids that trap the solar energy. These plastids remain in the slug, continue to photosynthesize and provide food for the slug. In effect, the creature becomes a solar-powered slug and is able to make its own food like plants do.

Photosynthesis needs around 2,000 to 3,000 genes, and animals do not have many of the critical genes.Researchers found that the slug has at least one gene required for photosynthesis in its nuclear genome, which has never been found in any animal. The critical thing is the plastids come from the alga, but the slug nucleus contains at least one, and probably more of the genes required for plastid functioning. The slug needs the alga to mature and complete its life cycle. It is totally dependent on the alga to survive. Once the slug has acquired a sufficient amount of plastids it can survive, like plants, for at least nine months by trapping solar energy and converting it into food.

This means the “baby” slugs are born with genes that support photosynthesis, but they have to gather their own plastids. Researchers on this matter say that if the slug and the alga both brave the ever-changing climatic conditions, the slug might evolve into a truly photosynthetic animal!!

Brena Sena (11)


At 7:51 PM, Anonymous Anonymous said...

Where are lowly sea slugs found? How does the sea slug retain the plastids that trap the solar energy? What is the sufficient amount of plastids a sea slug needs to survive, like plants, for at least nine months? How much does that amount translate into the amount of alga?


At 4:29 PM, Anonymous Allison Cornell said...

Wow! That's really cool how even with a fraction of genes to photosynthesize, the slug can reap the benefits of photosynthesis. How exactly is it able to use the energy gathered by the algae plastids? The plastids don't need to be in their original hosts to continue working? Very interesting article and creature!

~Allison Cornell (11)

At 10:52 PM, Blogger PWH said...

It is pretty interesting that the lowly sea slug can subsist on photosynthesis even if it initially has to depend on alga for the plasmids. Did this trait arise from some sort of mutation in the genome? Could this have been a product of environmental difficulties in finding food? They are known as "lowly sea slugs", but they must be close to the surface to photosynthesize, right?

-Helen Thi

At 11:02 AM, Blogger PWH said...

Thats awesome!

You said that the slugs eat algae and filter out the plastids which they use to get energy over the course of many months, does this mean that since the slugs don't have any reason to forage for more food during this time they simply go into a state or hibernation?

-Joe Alonzo

At 2:43 PM, Anonymous Anonymous said...

That's really interesting. It is a possibility that these slugs originally retained certain organelles from the alga as a type of camouflage? They look just like plants!

-Jane de Verges

At 4:04 PM, Blogger PWH said...

This comment has been removed by the author.

At 4:04 PM, Blogger PWH said...

I think that the slugs are a long way from evolving photosynthesis, but it is likely that it will happen. Where is the habitat? Why can't the animal survive indefinitely on the plastids it has consumed, but dies after nine months?

Jimmy Sullivan

At 6:56 PM, Anonymous Anonymous said...

That's an interesting way of getting the energy ther need. Are the plastids similar to plants? How efficent is this system?

-Duy Nguyen

At 9:26 PM, Blogger PWH said...

Wow! Amazing find! Who would have ever thought that an animal could use similar techniques to generate its own food like plants? I wonder from where this creature evolved from. Is it from plants or from another slug species? It is so odd that they actually suck the cytoplasm out of their food source. How very interesting. Good job.

Carlos A. Varela

At 10:03 PM, Anonymous Anonymous said...

I really liked this article. It is amazing how these lowly sea slugs are able to function like photosynthetic plants. What is the sufficient amount of plastids required by the slugs? Does it need more than one alga?

Tazneena Ishaque

At 11:37 PM, Blogger Dan said...

Wow, that's amazing. How efficient is the whole system? How long it takes for the slugs to achieve the necessary amount of plastids before they can survive solely on solar energy?

~Dan Hong

At 7:29 PM, Anonymous Anonymous said...

When it comes to life it seems there are not many boundaries that can not be broken. Can they produce energy like a plant does? If so, it seems like this might have some big benefits to the world if the process could be unraveled.

Allan Eldridge

At 11:09 PM, Blogger PWH said...

This discovery of a photosynthetic slug is absolutely astounding. The thought of an actual living organism, that's not a plant, in which is able to steel the photosynthetic properties of algae and evolutionarily ingenious. Now that we actually know the exact mechanism of how this system works, do you think there we will eventually have the knowledge to genetically engineer other organisms to work using this energy system?

-Kiel Boutelle


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