I have a super-earth world. The surface of the world is shallower due to extra gravity, so shorter mountain ranges and less ocean depths. The world orbits a binary star system at a distance of the furthest region of the habitable zone, both of the stars having masses of 0.93x that of our suns. The world is highly volcanic, approximately 15 to 16 times more volcanic than our planet.

Surface gravity: 1.35x of Earths.

Atmosphere thickness: 10x of Earths (a result of it being highly volcanic in comparison to earth.)

Atmospheric composition: Nitrogen 78%, 15% Oxygen, 5% Carbon dioxide, 2% Trace gases.

Temperature: rather hot, the tropical regions being 90 to 110 degrees Fahrenheit. (based on what I've tested on Universe Sandbox 2)

Land coverage: 75% water, and 25% land (but less water being present on this world as the oceans oceans are shallower mostly due to a lot of island formations)

Radius: 7750 kilometers

Day/Night length/full rotation: 28 hours.

Axial tilt: 53 degrees.

Orbital period: 1.15 years

Eccentricity: 0.025

How would the fauna and the flora of this particular world be due to its pressure?

  • $\begingroup$ So your CO2 won't be 2% nor 6%, now it will be 5%. Right? $\endgroup$
    – Ender Look
    Commented Jul 22, 2018 at 22:30
  • $\begingroup$ well, it's 5% Yes, less than what the atmosphere of Pandora has $\endgroup$
    – Neuryte
    Commented Jul 22, 2018 at 22:42
  • $\begingroup$ Pandora? Which movie? Avatar? Could you send me the link? $\endgroup$
    – Ender Look
    Commented Jul 22, 2018 at 22:43
  • $\begingroup$ By "thick atmosphere" do you mean density/pressure or height before you reach space ? Note that a very high altitude for atmosphere is unlikely as it would also imply a huge atmospheric surface pressure. $\endgroup$ Commented Jul 23, 2018 at 0:06
  • $\begingroup$ @StephenG in his other question he said 10 times the Earth atmospherical pressure. $\endgroup$
    – Ender Look
    Commented Jul 23, 2018 at 0:42

1 Answer 1



Your fauna:

  • Oxygen concentration is lethal for Earth's life due to oxygen toxicity at high values. Your creatures will need a lot of evolution to survive there.
  • Will have short lifespans with a lot of offspring due to damages produced by the high oxygen concentration that can't be fixed.
  • Insects will be huge because they're breathing through their skin and that produces a fine relation between surface/volume ratio and oxygen concentration.
  • All your fauna will suffer nitrogen narcosis which is quite similar to being drunk. You will need some evolution in their nervous system.
  • Bacteria will have more nitrogen to breathe and use to make aminoacids, with that proteins and with that plants and animals. It'll be quicker and easier.
  • All fauna will suffer hypercapnia, respiratory acidosis due to carbonic acid and carbon dioxide toxicity at high concentration. If you don't have a massive rework at the acid level of their organism they will die.
  • Water will become acid due to CO2, that will kill a lot of fauna in water, like coral and others.
  • Their deaths will reduce the planetary albedo and that will raise the temperature.
  • CO2 is a greenhouse gas and it will seriously increase the global temperature a lot of degrees.

Your flora:

Our atmosphere has $101.325 \text{ kPa}$ of pressure.

Your world: $$101.325 \text{ kPa} \times 10 = 1013.25 \text{ kPa} = 1.01325 \text{ MPa}$$

  • 15% O2.
  • 5% CO2.
  • 83% N2.

Now, I'll show you the partial pressure of that gases.

$$\begin{array}{|cr|ccc|r|} \hline \text{Chemical} & & \text{gr/mol} & \text{Mols} & \text{Fractal Mol} & \text{Partial Pressure} \\ \text{O}_2 & 15\% & 31.9988 & 0.4687 & 0.1363 & 138.14 \text{ kPa} \\ \hline \text{N}_2 & 80\% & 28.0134 & 2.8557 & 0.8306 & 841.61 \text{ kPa} \\ \hline \text{CO}_2 & 5\% & 44.0099 & 0.1136 & 0.0330 & 33.48 \text{ kPa} \\ \hline \textbf{Total} & 100\% & 104.02 & 3.44 & 1 & 1013.25 \text{ kPa} \\ \hline \end{array}$$

Let's start with the analysis!

Extremely hiper-lethal O2

You have more than 138.14 kPa of oxygen! That is too much. On Earth we have around 21 kPa of O2. Any value above 50 kPa becomes lethal to humans (and the majority of animals) due to oxygen toxicity that produces hyperoxia. In this answer I enumerate the symptoms of oxygen toxicity.

different problems that arise from a high oxygen concentration

These are some of the major damages produces by hyperoxia. All your fauna must to find a way to combat this issues, you should ask into another question about how to combat just the oxygen pressure.

Also, the increase of oxygen pressure will increase the oxidation speed of stuff (like metals) and even organic matter (like when an apple becomes darker after you cut it) and also will make things much more flammable.

The increase in oxygen pressure will increase the amount of ROS in the air. Reactive Oxygen Species produces enormous damages in our body at a molecular level, like:

  • Damages in the electron transport chain of mitochondrias (which produces our energy).
  • Lipids and proteins, which compound us.
  • And DNA and RNA which we use to carry our genetic information.

All these accumulative damages produce an oxidative stress, which increases our ageing speed due to the non-healable produced damages in our cells.

Your fauna will have shorter lifespans and a lot of offspring (if they survive) because maintaining an old organism in this environment is really difficult due to the constant damages.

The majority of these damages (for example retinal or skin damages aren't included) could be reduced by some evolution in their respiratory systems. I mean, if by some way you are able to reduce the oxygen input, all the damages in their inner organism could be avoided.

  • A way to do that is by an active transport in the cells membranes. Sadly that is impossible because it consumes ATP (energy) in order to maintain it, and the idea of breathing it to get energy, not consume it.
  • Another way could be with a semipermeable membran where oxygen is only allowed when there are low values in the body, but at high values, it's blocking the passage. I'm not sure if this is possible to achieve with oxygen.

In this answer I explain another effect of an increase in oxygen levels.

Also, another effect on animals will be produced, and I explain that in this answer.

Have you seen ever this terrifying creature? Luckily, I've never seen one, but sadly in your world, there will be nothing compared to your insects, because they will be extremely big.

Insects don't have a respiratory system. They breathe through their skin, so if you make them bigger they won't have enough cm2 of surface per gramme of insect. They will suffocate (because of surface/volume ratio decrease per size). On your planet there is **a lot of oxygen in air* so insects could be a lot bigger without suffocating.
* Insects have a respiratory system, but they don't have lungs or gills, they use other things.

On the good side, you could think that your fauna will have more oxygen to use, which means a faster metabolism.

Really very high N2

Your N2 value is 841.61 kPa. At values above 400 kPa nitrogen narcosis appear.

Nitrogen narcosis is quite similar to the effects of alcohol's drunkenness, cannabis, nitrous oxide breathing or drugs from the benzodiazepine family as diazepam or alprazolam.

  • It produces anxiety, a feeling of tranquility, a mastery of the environment.
  • It means losing the ability to recognize danger, impairment of judgement, multi-tasking and coordination, loss of decision-making ability and focus.
  • Vertigo and visual or auditory disturbances.
  • The syndrome may also cause exhilaration, giddiness, extreme anxiety, depression, paranoia.
  • More serious (not sure if your case) overconfidence, slowed mental activity, increased reaction time and errors in cognitive functions.
  • Reduction of both the perception of cold discomfort and shivering and thereby affects the production of body heat.

At your pressure, it can be "barely" compared to drinking 7 consecutive martinis...[citation needed]

Again, the solution may be something similar to the lungs evolution of oxygen or some kind evolution in the neural system:

Modern theories have suggested that inert gases dissolving in the lipid bilayer of cell membranes cause narcosis. More recently, researchers have been looking at neurotransmitter receptor protein mechanisms as a possible cause of narcosis.
The precise mechanism is not well understood, but it appears to be the direct effect of gas dissolving into nerve membranes and causing a temporary disruption in nerve transmissions.
Similar to the mechanism of ethanol's effect, the increase of gas dissolved in nerve cell membranes may cause altered ion permeability properties of the neural cells' lipid bilayers. [...]

On the good side, bacterias breath N2 and make aminoacids with them. Aminoacids are used to build proteins and they are used by plants and animals. More nitrogen in the air will make this faster and easier. Also an increase of carbon dioxide and nitrogen could aid the photosynthesis of plants increasing their grow rate.

Extremelly lethal CO2

Your CO2 partial pressure is 33.48 kPa. In this answer I explain the increase of CO2 by just a bit.

carbon dioxide toxicity explained with respect to different parts of the human anatomy

In this answer I explain in deep symptoms of hypercapnia. There you will note a table which says that a 5% CO2 concentration could kill you in 4 hours, at normal partial pressure, for you, it's a matter of minutes.

The worst part is that you can't just breath less in order to avoid it, because hypercapnia is matter of expel CO2, not breath it, and due your partial pressure it's impossible to get rid of it.

  • Increase the acidity of lakes and oceans because CO2 combines with water and become this acid.
    All your submarine fauna will cry.
    • All your coral will die of starvation because they will expect a reduction of 90% in their energy input due to coral bleaching.
      • Their dissolved white Calcium Carbonate (CaCO3) shells from their corpses will disappear and that would reduce the albedo of your planet, effectively increasing global temperature.
  • CO2 is one of the greenhouse gas which increase the global temperature of Earth. I don't want to do any calculation about it, but I'm quite sure it would increase several degrees the temperature, maybe 15 ºC or even much more, you have a lot of CO2 and a lot of pressure. Rember that CO2 is the second (9% - 26%) dangerous gas in the global warming.
  • CO2 is an asphyxiant gas and due to its higher molar mass compared to oxygen and nitrogen it may get sink in valleys, where the concentration is much higher than in other places, if there is no wind.
    Your fauna must be able to hold a higher acid value in their organism, not sure how.

On the other hand, as a good side, an increase of carbon dioxide and nitrogen could aid the photosynthesis of plants increasing their grow rate.

  • That means you will have to explain why plants haven't already consumed all this CO2. CO2 must be replenished by a huge amount of fauna or by an active process like volcanoes.
  • 1
    $\begingroup$ If I forget something please tell me and I'll try to edit it! $\endgroup$
    – Ender Look
    Commented Jul 23, 2018 at 0:49
  • 1
    $\begingroup$ Very informative, I love it. Thank you, I'm thinking of having the creatures have a much smaller respiratory system that'll limit the amount of oxygen intakes as well as some type of regulation like how our body does in terms of alkalizing the acidity of the blood. $\endgroup$
    – Neuryte
    Commented Jul 23, 2018 at 1:56
  • 3
    $\begingroup$ @Neuryte I've just found that the bicarbonate buffer system doesn't consume energy to be used! Even more, it's reaction is $\text{CO}_2 + \text{H}_2\text{O} \leftrightarrow \text{H}_3\text{CO}_3 \leftrightarrow \text{HCO}_3^{-} + \text{H}^{+}$, $\text{H}_3\text{CO}_3$ is a weak acid and $\text{HCO}_3^{-}$ is a conjugate base, together the acid level is neutralized without energy! Furthermore, when bicabonate ion is transfered in blood it counter act the acid level of other reactions as lactic acid (exercice) or ketones bodies (hunger). $\endgroup$
    – Ender Look
    Commented Jul 23, 2018 at 2:52
  • 2
    $\begingroup$ @Neuryte That meas your creatures just need to eat a lot of zinc in order to make enough carbonic anhydrase, which is used to make both reactios $\text{CO}_2 + \text{H}_2\text{O} \xrightarrow{\text{Carbonic anhydrase}} \text{H}^{+} + \text{HCO}_3^{-}$ "The reaction rate of carbonic anhydrase is one of the fastest of all enzymes, and its rate is typically limited by the diffusion rate of its substrates. Typical catalytic rates of the different forms of this enzyme ranging between $10^4$ and $10^6$ reactions per second". $\endgroup$
    – Ender Look
    Commented Jul 23, 2018 at 2:58
  • 2
    $\begingroup$ @Neuryte The reverse reaction is relatively slow in the absence of a catalyst. Carbonic anhydrance can also reverse this reaction removing the water molecule from it $\text{H}^{+} + \text{HCO}_3^{-} \xrightarrow{\text{Carbonic anhydrase}} \text{CO}_2 + \text{H}_2\text{O}$ $\endgroup$
    – Ender Look
    Commented Jul 23, 2018 at 2:58

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