Okay essentially I am designing an alien ecosystem with an ammonia and methane based metabolism. Here's the formula for the metabolism animal analogs use on this planet:

$$\ce{3CH2O + 4NH3 -> 3CH4 + 3H2O + 2N2 + energy}$$

You eat some formaldehyde (emperical form of glucose) and react it with breathed in Ammonia to generate methane, water, nitrogen and energy.

Basically I wish to know what blood analogue these organisms might use to transport the ammonia gas throughout their body

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    $\begingroup$ Have you worked out how much energy this reduction reaction produces per mole of glucose? I would like to understand how it compares with the oxidation reaction used here on Earth C6(H2O)6 + 6O2 $\rightarrow$ 6CO2 + 6H2O which produces about 2.84 MJ/mol. (Yes, that is megajoules.) $\endgroup$
    – AlexP
    Commented Aug 27, 2023 at 17:13

1 Answer 1



Ammonia and water are fully miscible. They dissolve into each other easily in all proportions, so you don't really need any special carrier molecules. Higher temperatures will drive ammonia out of solution into the gas phase, but at 60F the equilibrium solution is still over 35% ammonia by mass, so you really don't need to worry about water not being able to hold enough ammonia on its own.

What you may need is some method of buffering pH, as small quantities of ammonia dissolved in water-based blood will make it strongly basic. The fundamental cellular chemistry of your world may well be adapted to more alkaline conditions than we are, but they still probably won't appreciate the swings in pH produced by using up ammonia. Chloric acid or carbonic acid could by used as buffering agents, leading to ammonia being transported partially in the form of ammonium chlorate or ammonium carbamate, both of which are also highly soluble in water. Carbonate, sourced from carbonic acid, is a buffer in terrestrial organisms, and some molluscs neutralize ammonia as ammonium chloride (not chlorate; the chloride in this case is a neutralizing agent for ammonia excretion, not a temporary buffer agent for ammonia transport).

  • $\begingroup$ They will also need to deal with the byproducts - do Methane and Nitrogen behave similarly? $\endgroup$
    – IronEagle
    Commented Aug 28, 2023 at 1:56
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    $\begingroup$ @IronEagle No. Methane and nitrogen have fairly similar solubility curves, and both are much, much less soluble than ammonia in water. $\endgroup$ Commented Aug 28, 2023 at 13:51

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