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I'm trying to create an original species within semi-realistic biological constraints.

I need a way for a giant (7-8 feet long) arthropod to convert large amounts of CO2 into breathable oxygen for personal use. Be it through a reaction or breaking the bonds of the molecules, I just need a lot of oxygen to result from it. They breath through spiracles like most arthropods, but have very different biology overall and so can breath more actively than a lot of smaller invertebrates.

There is no water within the ecosystem it resides in outside of a few specific living organisms, since the surface temperature is always above 200 degrees Celsius. There is no sunlight, this is a closed ecosystem within a giant cave system. There are no plants, only fungi, animals and microscopic organisms.

I am only providing this information to demonstrate the chemical constraints of possible solutions. The way that energy is obtained isn't relevant to my question, I just need to know what chemicals could do what I need, even at different temperatures than the ones provided.

I've looked into things like Lithium peroxide, which is used in spacecrafts to convert CO2 back into oxygen and reduce CO2 overall within the cabin, but its an inorganic compound that I couldn't feasibly find a way to work it into the biology of these creatures.

Carbon capture technology doesn't really help me either, since from what I can find the Amines used to react with and bind to CO2 for transport don't release Oxygen as a byproduct or anything like that.

I don't have a lot of knowledge on chemical reactions, so forgive me if there's an obvious answer I wasn't aware of.

This organism is an invertebrate, and evolved from a giant species of moths within this world. A population of them were isolated within another dimension that is nearly identical to The Nether from Minecraft.

For a number of reasons; such as the fact that this organism has an internal body temperature of about 1000 degrees Celsius; this arthropod species doesn't have almost any water within its body and doesn't need water to survive. A fictional element I made for this world acts as a replacement for water within its biology. This element doesn't have the properties I need to achieve my goals for this organisms respiration.

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    $\begingroup$ Lithium peroxide doesn't convert CO2 into oxygen, it releases some of the oxygen bound up in the lithium peroxide as it absorbs the CO2 to form lithium carbonate. As for being inorganic, not much organic chemistry is going to happen at 1000 °C, and CO2 seems like an unlikely product of respiration. But the biggest problem is that if you're combining oxygen with something for energy, you're going to need energy to reverse this...you can't just separate things so you can then react them again for more energy. $\endgroup$ Jan 2 at 2:47
  • $\begingroup$ i am aware that it isn't a direct conversion of CO2 to oxygen, I was just simplifying the terms i used. by itself it achieves the same goal, getting oxygen from CO2, even if its only a byproduct of the reaction. the energy issue isn't really the point of the question, I want to know if there is a way to get oxygen from CO2 without Lithium peroxide or photosynthesis, not where the energy to do it comes from. I'll figure that out myself later. $\endgroup$
    – Brimstone
    Jan 2 at 2:58
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    $\begingroup$ But that's pretty much where you need to start. If you want to define details of how respiration and energy balance work in this ecosystem, the energy source is not an extraneous detail that can be left for later. It's not just a matter of having some chemical make oxygen. $\endgroup$ Jan 2 at 3:22

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There are a number of issues with this scenario

  1. Lifeforms that exist in a 200 C environment, even without having an internal body temperature of 1000 C, are far removed from any Earth biology. If you are inventing an element to take the place of water (a compound) in the creatures' biology, then you may as well ignore the need for oxygen or replace it with another element.
  2. Any oxygen that is created in a 1000 C environment is going to combust with any carbon it encounters (and various other elements) pretty much instantly. So, unless the creature is creating the oxygen and somehow magically whisking it away into an internal compartment made of something completely non-reactive, oxygen will very quickly combine with something else into an oxide and be unavailable for whatever purpose the creature requires it for. Speaking of which...
  3. While you have not stated why the creature requires oxygen, note that it requires energy to separate carbon dioxide into carbon and oxygen. Since you have specified that there is no sunlight available, precluding the obvious photosynthesis route for creating oxygen, there needs to be some other energy input, otherwise this would be a biological perpetual motion machine. (Again, if this is the case then stop worrying about the scientific "realism" of requiring oxygen.)

If oxygen is required for some purpose other than respiration then the creature's temperature, and that of the overall environment, need to be lowered and an energy input provided for. If the oxygen is for respiration then it makes no sense from an energy perspective - just ignore the issue the way you have with the non-water biology, do not try to explain it.

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  • $\begingroup$ +1 Good answer that highlights and adresses the worldbuilding issues at hand. however: I disagree with this statement: "If the oxygen is for respiration then it makes no sense from an energy perspective". We very much have organisms on our planet that do exactly that: plants. They produce oxygen at daytime and consume it again later during nighttime (though much less then they produce). Given a cycle between more and less abundant energy the "produce oxygen for later respiration" can be rationalized. $\endgroup$
    – datacube
    Jan 2 at 8:30

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