Bizarre sea slug is half plant, half animal

http://www.mnn.com/lifestyle/pets-animals/stories/bizarre-sea-slug-is-half-plant-half-animal-0

by absconditus • 16 years ago

106 46 16 years ago

Any chance of genetic modification so that I too can utilize photosynthesis? I love food, but it'd be nice to not have to worry if I was stranded on a deserted island in the tropics.

jacquesm2• 16 years ago

You could breathe your homegrown oxygen too that way!

On a more serious note, the sun puts out about 1KW per square meter of receiver that is exactly perpendicular to the incident rays, in full sunlight. So theoretically there is enough power there, but in practice photo-synthesis is not efficient enough to make this happen, typically somewhere around 5% of the energy gets captured, and that's for a very dark plant. So if your cross section towards the sun is .2 m^2 and you convert at 5% efficiency then you can expect about 10W from that in usable energy. There is a reason leaves are relatively flat and can change orientation.

http://en.wikipedia.org/wiki/Photosynthetic_efficiency

It's not easy, being green.

sliverstorm2• 16 years ago

Of course, you wouldn't need oxygen. You need oxygen to break down compounds; you need carbon dioxide to build them. Your lungs would have to switch to absorbing CO2 and expelling O2.

Now, on the other hand, if you continued to eat food AND synthesized, that could get pretty cool. I'm not really sure what you'd wind up expelling in that case.

baddox2• 16 years ago

Also, when you're the only guy on the block that's able to turn energy into a useful form, you tend to get eaten a lot.

JeanPierre• 16 years ago

This brings up a somewhat more scary discussion: It's more efficient to be a cybernetic organism than a gene-modified human with genes from plants.

If I get this correct, this (cited) Wikipedia-article says that solar cells with a 0.01 m^2 surface area would produce approximately 1.4 watt. Multiplying 1.4 watt by 20, to get a 0.2 m^2 surface area, gives us 28 watts.

http://en.wikipedia.org/wiki/Solar_cells#Energy_conversion_e...

eru6• 16 years ago

It would be a lot easier if you hadn't been conceived, yet.

earl• 16 years ago

But you'd get fat by being outside. That seems suboptimal.

kalid• 16 years ago

Weight control: wear a jacket.

RyanMcGreal• 16 years ago

Not if you're a programmer.

tocomment• 16 years ago

I'm guessing you'd need some huge surface area to power a human with photosynthesis.

Perhaps an acre (wild guess)? Maybe someone could look that up?

sprout• 16 years ago

http://duckduckgo.com/?q=calories+in++1+pound+of+whole+wheat...

Gives 1538 Calories per pound of whole wheat flour.

According to these folks an acre of wheat yields 42 bushels: http://www.wheatfoods.org/AboutWheat-wheat-facts/Index.htm

At 60 pounds/bushel that gives you 2520 lbs. * 1538 Calories = 3875760 Calories / acre / year. We'll divide by two to assume you're mixing wheat with some foods that are a little less calorically dense, because you'll want at least some green leafy veggies and beans for iron and protein, and that gives us 1937880 Calories per acre per year, divided by 365 days in a year yields 5309 Calories per acre per day.

So, back to the original point, it looks like you can easily power a human using half an acre of land and photosynthesis. Possibly one quarter of an acre if you're willing to live on bread alone. (Whole grain being not so unhealthy as white.)

SpacemanSpiff• 16 years ago

2000kCal = 2.3kWh Assuming 5% conversion efficiency (http://en.wikipedia.org/wiki/Photosynthetic_efficiency) Win = 46.5kWh. "standard" solar radiation equals approximately 1kW/m^2, so given 12 hours of solar exposure per day this works out to about 3.9 square meters.

Whenever I do these kinds of calculations I'm always amazed at how much power the sun is able to provide on a square meter 93E6 miles away!

mhd• 16 years ago

So you'd be okay with a moldy green look?

Hmm. Women who want to stay slim + algae. Maybe we can finally get real live Orion slave girls… (Not actual slaves. Not actually from Orion. No refund possible. Ask your dermatologist, divorce lawyer and Michael Okuda for side effects)

sliverstorm2• 16 years ago

green women sounds kind of sexy

kiba• 16 years ago

I want to be powered by photovoltaics!

nollidge3• 16 years ago

Sure! Coax a retrovirus into reverse-transcribing some chloroplast-supporting genes into your skin cells, eat a salad, and you're all set!

eru6• 16 years ago

And we already have retro-virus genes in our genome.

davidw2• 16 years ago

"Half plant, half animal" seems incorrect: it's an animal that has borrowed some DNA and cell parts from algae.

eru6• 16 years ago

Or vice versa: It's plant DNA that has infected an animal and uses it for reproduction. The algae's chloroplasts haven't figured out how to survive the step into the next generation, yet, though.

crayz• 16 years ago

Right. If the genes were giving the snail sores, we'd call it a virus. Perception is reality

nollidge3• 16 years ago

But the plant DNA is encoded into its genome. "Half" is stretching it, but it's certainly partly plant since it received the plant genes via horizontal gene transfer from the algae.

rlpb• 16 years ago

Mitochondria are hypothesised to have originated from separate organisms. Could this be additional evidence of the same process half way complete?

http://en.wikipedia.org/wiki/Endosymbiotic_theory

flannell• 16 years ago

Here's a clip of it moving.

http://www.youtube.com/watch?v=yQNIpW0LlsU

kentosi• 16 years ago

I seem to remember a while back when scientists discovered a jellyfish with similar attributes. Does anyone else recall?

js22• 16 years ago

Follow the blog spam.

So this article is a summary of, and links to http://www.livescience.com/animals/green-slug-animal-plant-1...

But that article only mentions its source "The finding was first reported by Science News" w/o a link. Some googling turns up:

http://www.wired.com/wiredscience/2010/01/green-sea-slug/

which appears to be the original reporting.

absconditus• 16 years ago

The article is actually from Science News. This is evident by the byline and the Science News logo near the top of the article. I apologize for not doing better checking.

http://www.sciencenews.org/view/generic/id/53496/title/Sea_s...

js22• 16 years ago

Notice the publication date on that is Feb 13th though. Science News articles sometimes appear first at wired.com for whatever reason.

WingForward• 16 years ago

And posted here: http://news.ycombinator.com/item?id=1051809

robryan• 16 years ago

Good example for an argument with anyone who doesn't believe in evolution.

loewenskind• 16 years ago

What new capability now exists that didn't before? Not for the snail, but over all.

Bizarre sea slug is half plant, half animal

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