Photosynthetic Animals

[Theorist]

I can't remember if I put this on AF or ToS, but I first saw it almost 2 years ago.

Green Sea Slug Is Part Animal, Part Plant | Wired Science | Wired.com



Anyways, if I could photosynthesize, I'd be gone. No need for society to give me food, I'd be up an outta here like that.

Interesting article though. Photosynthesis in animals is fairly new

[Raiden]

Heh

It is not new, by any means.

Corals, in phylum Cnidaria, produce food two ways; the polyps use their nematocysts to capture small animals floating in currents, and then they have symbiotic algae that cohabit within the polyp's body; they photosynthesize sugars for the coral in addition to the animal and plant proteins captured by the polyps. Considering phylum Cnidaria is the oldest phylum next to Porifera, and nudibranchs are molluscs, which came about later, the use of symbiotic plantforms to synthesize extra food is anything but new.

Furthermore, the larvae of many amphibians, and sometimes even the adults, do the same thing but for a different reason. They have algal cells cohabiting within their own tissues that carry out photosynthesis, but the amphibian does not utilize the sugar; it actually uses the algae as an internal oxygen factory to supply extra oxygen to its cells. Considering there are many amphibians that lack lungs and breathe through their skin, having an internal source of oxygen is a very useful trick.

[Theorist]

I think it's the first time though that an animal has been able to survive completely off of photosynthesis for long term periods, such as a year

[Raiden]

Originally Posted by Theorist

I think it's the first time though that an animal has been able to survive completely off of photosynthesis for long term periods, such as a year

Nope.

Corals can go for very long periods without much food, but die quickly without enough light.

[Theorist]

Sorry, should have said except corals, it says that in the article that this is the 1st time except corals, which are mostly immobile compared to the slug

[auroraglacialis]

Pierce emphasized that this green slug goes far beyond animals such as corals that host live-in microbes that share the bounties of their photosynthesis. Most of those hosts tuck in the partner cells whole in crevices or pockets among host cells. Pierce’s slug, however, takes just parts of cells, the little green photosynthetic organelles called chloroplasts, from the algae it eats. The slug’s highly branched gut network engulfs these stolen bits and holds them inside slug cells

It also says that the slugs can actually make chlorophyll themselves. That really is special. Though they seem to also eat algae a lot, so it is not that they really only live on photosynthesis...

[Theorist]

Originally Posted by auroraglacialis

It also says that the slugs can actually make chlorophyll themselves. That really is special. Though they seem to also eat algae a lot, so it is not that they really only live on photosynthesis...

I think they can survive up to a year without eating any extra algae though, and just having light from your average big building walmart type ceiling light.

[Moco Loco]

I imagine living by photosynthesis alone for any extended amount of time would wear the slug out, even if it could survive up to a year.

[Theorist]

yeah, I think when it says the slug can live for a year without algae, it probably means they left there in the water till it died

[Raiden]

Originally Posted by Theorist

yeah, I think when it says the slug can live for a year without algae, it probably means they left there in the water till it died

That's not true....

Somehow I doubt that someone would let a study drag out for a year just to starve a nudibranch to death. It's possible to count the number of glucose molecules made by photosynthesis, and since each glucose molecule accounts for ~50 ATP molecules, and each cell needs to make a certain amount of ATP for the animal to survive, you just need to whip out a calculator and multiply it out to find out how many days it can go without consuming food.

[auroraglacialis]

I did find it nowhere that it says the slug can survive for a year without food. I think that was a misreading of someone. In the experiments (if I found the correct paper) they starved them foe 12 weeks though, which they seem to survive.
PLoS ONE: Foraging Behavior under Starvation Conditions Is Altered via Photosynthesis by the Marine Gastropod, Elysia*clarki

[Theorist]

here's one citing that they can live a year (their entire lifespan without eating, after they eat some algae)

Solar-powered sea slug harnesses stolen plant genes - life - 24 November 2008 - New Scientist

"Young E. chlorotica fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in earlier work."

And, I think they let them live for a year, considering that this person studied them for 20 years

"After 20 years of studying the sea slug Elysia chlorotica, biologist Sidney Pierce recently discovered a trait unprecedented in the animal kingdom - sea creatures were producing chlorophyll."

Photosynthetic Sea Slug Snarfs (And Steals) Algae DNA

[Raiden]

Well, if it no longer needs any food because it photosynthesizes most of it, then it doesn't really matter.

When humane behavior goes out of control, people become humaniacs and no longer think with reason, just feeling.

[Aquaplant]

Originally Posted by Raiden

When humane behavior goes out of control, people become humaniacs and no longer think with reason, just feeling.

Is it even possible to be too humane? Isn't that a contradiction in itself?

I mean that if humane behaviour becomes detrimental to life, then can it even be considered humane anymore?

[Theorist]

Originally Posted by Raiden

Well, if it no longer needs any food because it photosynthesizes most of it, then it doesn't really matter.

When humane behavior goes out of control, people become humaniacs and no longer think with reason, just feeling.

oh, I'm just saying, it would have been kinda sad watching the slugs knowing "oh, we just have to wait till they die now"

I don't think it's inhumane, I mean it essentially lived out it's whole life. I'm just saying if I were that scientist I'd be a little sad knowing I was going to watch this thing till it died, but that's just me.