[Zombies] Going Green?

[Minuteman37]

Trying to build some less unrealistic zombies for an up coming low point survival game. I'm wondering if the undead having photosynthetic skin could hypothetically provide enough calories for them to not just starve within the first few weeks of the outbreak?

I'm also wondering just how much more efficient a humans metabolism could be made especially if they're functioning as an effective zombie.

I know these questions won't have simple answers but the GURPS community never ceases to surprise me.

[Johnny1A.2]

Originally Posted by Minuteman37

Trying to build some less unrealistic zombies for an up coming low point survival game. I'm wondering if the undead having photosynthetic skin could hypothetically provide enough calories for them to not just starve within the first few weeks of the outbreak?

Photosynthesis requires raw materials as well as sunlight. Your zombie will still need to obtain the necessary nutrients to do anything with photosynthetic skin. You can get carbon photosynthetically by breaking up CO2, that's how it works, but you have to have to other stuff to combine with the carbon.

[Minuteman37]

Originally Posted by Johnny1A.2

Photosynthesis requires raw materials as well as sunlight. Your zombie will still need to obtain the necessary nutrients to do anything with photosynthetic skin. You can get carbon photosynthetically by breaking up CO2, that's how it works, but you have to have to other stuff to combine with the carbon.

Well yes, I do plan on these zombies eating people and drinking water and such. I'm looking at ways to make all that stretch.

[Phantasm]

Isn't there a fungus that turns ants (and other insects?) into what are effectively zombies? How long do those zombie-ants last compared to regular non-infected ants?

[johndallman]

Originally Posted by Minuteman37

I'm wondering if the undead having photosynthetic skin could hypothetically provide enough calories for them to not just starve within the first few weeks of the outbreak?

Humans have a high metabolic rate and a low surface area to volume ratio. This can be useful for very small creatures with low metabolic rates, but it's pretty hopeless for human-sized animals.

[Dustin]

Doing some wikipedia math, it seems a largish person has 2 square meters of skin, which at a high insolation level of 7 kilowatt-hours per square meter per day, comes out to 14 kilowatt-hours per day, assuming perfect energy capture and transformation. (Maybe there's a mirror on the other side of the zombie, to get the sun from both sides.)

14 kWh converts to about 12 million calories (small c), or 12000 food Calories. What a surplus! Sadly, we now start cutting back. Actual photosynthesis is only 3-6% efficient, with a theoretical maximum of 11%. Our best case scenario has reverted to 1300 Calories per day, which is probably plenty for a cold-blooded ambush predator ("slow zombie"), but not a "fast zombie" unless they have some ability to store energy for those bursts and regain it during rest periods.

[Culture20]

Originally Posted by Phantasm

Isn't there a fungus that turns ants (and other insects?) into what are effectively zombies? How long do those zombie-ants last compared to regular non-infected ants?

Not very long. If I recall correctly, their new drive is to drop to the forest floor, climb under the first leaf they find before they die and spread new spores. The fungus "wants" as much energy left in the body as possible for reproduction.

[(E)]

There might be some energy gains to be made by making the zombies cold blooded. Slow (quiet) zombies by night and faster zombies by day.

[mhd]

Given the skin care regime of your average zombie, this would seem a bit ineffective. (Well, maybe it's a subdermal layer, and when zombies go hungry they naturally try to expose it, thus giving a reason for their usual flayed appearance).

But low energy output would be perfectly fine, as that would give a reason for dietary supplements, i.e. people. Unless, of course, these zombies attack just to spread the disease and not for raw food Soylent.

[Boomerang]

What if the zombies are like radiotrophic fungus and derive energy from gamma rays instead of using photosynthesis?