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A follow up question for What is the method to produce food within a volcano caldera?

How can a plant harness magma's heat to "photosynthesize"? It is very different from an animal, which can move freely. The plant should have a different mechanism to harness the heat, then store the harnessed energy. Bonus points to answers that can reasonably provide how and where (in the plant, I suppose?) to store that energy. I don't know if "starch stockpiling" will be applicable to this plant.

Of course, the plant is fire and heat-resistant in all parts due to the iron-carbon composite (or whatever, but it is basically a fireproof mostly-carbon based).

My initial idea is to have roots that stretch to magma in one side, and to water or cooler earth on another side (I read somewhere that you must use alternating hot and cool parts to harness energy from geothermal, but that's as far as I understand).


This question graduated from the Sandbox.

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    $\begingroup$ Infrared photosynthesis can be the answer. $\endgroup$ – Alexander Sep 25 '17 at 18:11
  • $\begingroup$ There is a whole class of organisms that live under these conditions in the real world. I am not a biologist but a quick google search found this article from the NY Times nytimes.com/1982/04/24/us/… PS. they do not photosynthesize $\endgroup$ – Vorsprung Sep 26 '17 at 8:18
  • $\begingroup$ @Vorsprung that's why I put it in quotes. Do you have any suggestion on alternative wording? Seems people think I misunderstand photosynthesis (which I'm not) $\endgroup$ – Vylix Sep 26 '17 at 8:24
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    $\begingroup$ I understand you but the gist of my comment was that this is a known phenomena - I don't have the expertise to write a proper answer. Maybe saying "how can a plant convert the heat of a volcano into energy" $\endgroup$ – Vorsprung Sep 26 '17 at 8:31
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The only conceptual change I would need to see is that the photosystems would need to be replaced with thermosystems. Plants, as you may know, harvest photons with photosystems these use pigments to capture light, and thus excite electrons for carbon fixation (synthesis).

photosystem cartoon

In theory, compounds that capture heat to excite electrons might use a similar scheme. Muller has spent time thinking about this. See his papers here.

Beyond the fact that thermosynthesis has not been documented, the main biological problem is that life, which is water based, doesn't do well above the boiling point. In the deep sea, pressure offsets some of the problems of extreme heat, but in a volcano (unless it is under pressure) you will see cells lysing, tissues melting, and disorder abounding.

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SMH, this isn't Photosynthesis

Photosynthesis is the process by which an organism takes in sunlight as an energy source. A plant is an organism capable of performing photosynthesis.

An organism powered from lava isn't a plant let alone performing photosynthesis.

After that clarification:

An organism needs access to an energy source and nutrients. In plants they take in sunlight and nutrients and create sugars which can later be reacted with oxygen anywhere in its body to provide on demand energy to fulfill some biological role. Similarly, animals eats plants and turn them directly into energy and save the rest as fats which they can burn later on demand.

All your creature needs to do is absorb certain chemical compounds from its environment and use the volcanic heat to transform them into larger compounds that can be easily reacted to with a freely available external compound to produce energy. Where it stores this energy is purely your preference however depending on how in-depth you get with the chemistry you may wish to centralize it in thermally protected pockets.

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All energetic systems are, at seventh and last, about electron exchange. The three common forms in life systems are chemical oxidation, chemical reduction, and ion exchange depending on the system and the purpose of the reaction. So any system is going to have to use at least one of these systems (usually they do all three), there are two energy sources present in a volcanic setting:

  1. The first energy source is the heat energy of the up-welling magma to tap into that energy I'd start by looking at the chemical/mechanical structure of the thermocouple to start designing a heat-energy rather than light-energy conversion. Thermocouples use heat energy to excite electrons and promote electron flow, given that a magma dwelling organism isn't going to be, strictly speaking, organic "wiring" might be more appropriate than a circulatory system. To that end a thermocouple-like structure that creates free electrons for reductive processes would allow these creatures to source raw chemical material for their bodily structures and reproduction. This system is not super useful when it comes to storage structures rather relying on fairly continuous thermal inputs without which it will go dormant, as it's not alive in the traditional sense it doesn't die when deprived of energy inputs though it just slows right down until the heat comes back.

  2. There are also a number of mineral compounds that produce energy when reduced rather than requiring energy from light or heat to be reduced. A number of the Hyperthermophilic extremophiles found in thermal vents and geysers have learn to use these compounds as their energy and building block sources. The main chemical reaction exploited by these lifeforms is a sulfate ion reduction, the energy from reducing sulfate is used to oxidise carbon compounds and hydrogen for carbohydrate production. In a purely magmatic system a number of energy releasing compounds are available and dissolved water, carbon dioxide, nitrates and other gases can provide the building blocks for proteins and carbohydrates so these life-process reactions are viable. Plants could exploit the same pathways as bacterial extremophiles or use a symbiotic relationship with microbes that do. Normal storage techniques, sugars, starch, etc... are used in this system.

One or both of the above energy tracks should give you a line on feasible chemical/energy pathways for a lifeform, or even an ecosystem that exists in a hot rock environment with a caveat; none of the lifeforms I'm basing the chemical processes on are physically/chemically stable above about 130 Celsius, the thermocouple based exchange is possible to over 2500 given high levels of certain rare elements like Rhenium, otherwise 1800 Celsius is the top temperature for these systems.

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  • $\begingroup$ This is a bit short, can you please expand your answer? I've already researched for extremophiles, but I didn't understand the sulfur whatever cycle they're using (if you can kindly explain it, that will be great!) $\endgroup$ – Vylix Sep 25 '17 at 18:15
  • $\begingroup$ @Vylix Sorry about previous answer was getting to the end of my "day" and winding down so I sketched something really quickly. $\endgroup$ – Ash Sep 26 '17 at 11:30

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