Can an organism have several types of oxygen carriers in its blood?

Note that I am not asking how the creature could have evolved, that is too much sci-fy, genetically engineering or Deus Ex Machina evolution fits fine.

The idea to use several kinds of oxygen carriers is to be able to survive in very different environments (the last substance isn't very important if it causes problems):

  • Hemoglobin: Standard carrier. Contains iron. Most efficient for normal purposes.
  • Hemerythrin: Contains iron. Can also be made with cadmium. Usually lacks cooperative binding, which means that it can only carry 1/4 of the O2 carried by haemoglobin (in some brachiopods it does).
    Hemerythrin affinity for CO is lower than its affinity for O2, unlike hemoglobin which has a very high affinity for CO, i.e: resistant to CO poisoning.
    Recent evidence has revealed hemerythrin to be a multi-functional protein – contributing to innate immunity and anterior tissue regeneration in worms.
  • Hemocyanin. Contains copper, which means it doesn't need iron.
    Lacks of cooperative binding, which means that it only carries 1/4 of the O2 carried by haemoglobin (in some hemocyanins of horseshoe crabs and some other species of arthropods, cooperative binding is observed,). However, it doesn't lose efficiency in cold environments with low oxygen pressure as hemoglobin does. In addition, it can stand elevated temperatures as high as 90 degrees Celsius.
    Hemocyanin oxygen-binding profile is also affected by dissolved salt ion levels and pH.
    It's believed to reduce cancer effects.
  • Vanabins: Contain vanadium or other rare minerals. Are very bad for transporting oxygen but are poisonous for many predators, parasites and microorganisms.

The question is if it could be possible to an organism to have all these substances or would them produce problems between them? If that is true, could the same organism has all these substances but not at the same time (i.e: it changes of substance according to the environment)?

  • $\begingroup$ I am not aware of the problems between proteins, but do you want them actually work, all at once? $\endgroup$
    – Alexander
    Feb 7, 2019 at 22:52
  • $\begingroup$ @Alexander, if it isn't possible it doesn't matter, the creature could switch according to the environment. $\endgroup$
    – Ender Look
    Feb 7, 2019 at 23:02
  • 1
    $\begingroup$ Haemoglobin is not "made of" iron, and haemocyaning is not "made of" copper. They are metalloproteins containing iron and copper, respectively. $\endgroup$
    – AlexP
    Feb 8, 2019 at 5:01
  • $\begingroup$ @AlexP, I know, but since they have iron/copper inside, it's easier to understand like their are made of iron/copper. $\endgroup$
    – Ender Look
    Feb 8, 2019 at 13:31

3 Answers 3


We have two different oxygen carriers in our blood.

Humans use Hemoglobin F in utero. That oxygen carrier is downregulated when we are born and Hemoglobin A is upregualted to take its place.

So too your creature with its different specialized carriers. Presumably it occupies different sorts of oxygenation niches according to life cycle or circumstance. Having different oxygen carriers it can up and downregulate make sense.

I can think of no reason why one carrier would necessarily interfere with another. Their niches are separate. If you had a special oxygen avid carrier suitable for toughing it out in anoxic environments but then got to a high oxygen environment, the anoxic carrier would just be saturated with oxygen and hang around that way until it was cleared. Your high oxygen environment low avidity carrier would come on line to let you do your fast oxygen-hungry metabolic gymnastics. If you then went back to anoxic areas, the low avidity carrier would hang around empty and the anoxic carrier would come back on line to get you by.

I think this sounds like a reasonable system. It is more likely that permutations of a single carrier would evolve than a bunch of completely separate carriers. But there is precedent for picking up an oxygen carrier from a completely different species - legumes are plants and they have hemoglobin that they somehow swiped from an animal in years far past. You creature might have pulled similar evolutionary shenanigans.

  • $\begingroup$ Interesting. I did know about Hemoglobin F and A, but since both carriers are only used in very specific situations (pre-born, after-born) I wasn't sure about it. I don't know why but I was expecting some kind of harmful reaction when trying to combine different oxygen carriers, it's good that it doesn't happen. Anyway, the question is still young (3 hours) so I should wait a day or two before do anything. $\endgroup$
    – Ender Look
    Feb 8, 2019 at 1:22
  • $\begingroup$ @EnderLook In their role of oxygen carriers, they can only cooperate. In their role as chemicals, however... I'm not saying that they would necessarily have chemical conflicts, just that increasing the chemical soup increases chances for unwanted fun. But you're probably not giving the exact chemicals, so plenty of room for suspension of disbelief. That said, they could have an averse reaction to some chemical or other that only affect them noticeably when using a certain oxygen carrier or something. It probably wouldn't be really dramatic, though. $\endgroup$
    – Ed Grimm
    Feb 8, 2019 at 6:34
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    $\begingroup$ I used a very similar mechanism in the design of a swamp dwelling alien creature, though there the switch to high metabolic state and increased O2 consumption was triggered by the presence of calorifically rich carrion. It only produced the more expensive, more effective transport proteins when it could be sure of a good return on the investment. $\endgroup$
    – Joe Bloggs
    Feb 8, 2019 at 6:56
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    $\begingroup$ +1 for "evolutionary shenanigans" explained so well $\endgroup$
    – Harthag
    Feb 8, 2019 at 14:26

The biggest issue would be efficiency.

Generally speaking, you would find that only the most efficient oxygen carrier at any point in time got to do the work. Oxygen carriers work by making it energetically advantageous to bond the oxygens to the molecule while in a high oxygen environment like the lungs, and then release it later in lower oxygen environments throughout the body. If I had two carriers, and one bonded more vigorously than the other, it would strip oxygens off of the weaker carrier. The result would be that, in general, the weaker carriers would simply not be carrying any oxygen, or would only be carrying it in times of luxury when there's lots of oxygen to be had.

However, if the creature inhabits many environments, its possible that one carrier could be advantageous in one environment and one could be an advantage in another. For example, one might have hemoglobin for one's living environment, and hemocyanin to function while hunting in cold hunting grounds where your body temperature plummits outside of hemoglobin's operating range.

The disadvantage, of course, is waste. Red blood cells are about 40% of our blood by volume. If you had several redundant carriers, you would need to have even more oxygen carrying cells. That could prove difficult.

  • $\begingroup$ That assumes that the different carriers need to occupy the same locus, which is not always the case. Hemocyanin, the carrier in marine invertebrates and many terrestrial arthropods, exists freely in the bloodstream (well, hemolymph) rather than inside blood cells like hemoglobin. $\endgroup$
    – MarqFJA87
    Mar 16, 2019 at 14:07
  • $\begingroup$ @MarqFJA87 So I think you would still have an issue because the oxygen has to go through the same fluid to go from the blood cells to the respiring cells. However, I should thank you because you made me go look up how hemoglobin works, and like all aspects of the body, it's {bleep}ing brilliant. Hemaglobin's structure shifts when it binds with oxygen to make it want to bind with more oxygen, and releasing the oxygen (in the lower pH, high CO2 environment) causes it to want to release it more. Thus instead of the usual hyperbolic saturation curves we're used to for absorptives... $\endgroup$
    – Cort Ammon
    Mar 16, 2019 at 15:14
  • $\begingroup$ ... it has more of a sigmoid curve. It's better at pulling oxygen out of the air when it's in the lungs, and its better at releasing it in the environments associated with the body! I love this stuff! $\endgroup$
    – Cort Ammon
    Mar 16, 2019 at 15:14

I see no issues if the organisms has the capability of synthetizing more than one, but actually synthetize one at a time, based on the circumstances.

I.e. switch from hemoglobin to hemocyanin when either the body has a deficiency of iron or it is living in cold temperatures, like during winter.

Since each of them has a different efficiency, it makes sense that only the most fit for particular conditions is used. Everything else would simply be a poor use of resources, which for a living organism are always limited.

If you think of our body, in our eyes we already have two types of receptors: one for day light (better resolution, color discrimination), one for dim light (no color discrimination, higher sensitivity), and we use each of them in different cases.


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