I am workin on an ecosystem based on life within the rings of a planet. I will create creatures from single celled organisms, to algae/ lichen, plankton/worms and scales of predators leading to large lifeforms.

Saturn's rings have their own atmosphere mostly comprised of oxygen and water is abundant, this covers two of the issues needed for life.

Tardigrades can withstand high levels of radiation, so I can have a similar ability for all the lifeforms, but tardigrades go into a dormant phase in space, expelling all of their water and lowering their metabolism via cryptobiosis, this allows them to survive the extreme cold.

Would the creatures need blood using something like liquid helium or another fluid that remains liquid at very low temperatures? or other anatomy to help insulate the lifeforms.

What will a creature need to allow it to function and be mobile at extremely low temperatures?

  • $\begingroup$ Mobility seems to be quite the stretch. While I don't discount that sessile organisms might be possible using something like photosynthesis, movement in space requires propellant. I'm not sure how that could work. $\endgroup$
    – John O
    Commented Mar 2, 2020 at 20:48
  • 1
    $\begingroup$ @JohnO The larger creatures would expel their waste to propel and I had considered some jumping between rocks and waiting for another rock to come into their path. $\endgroup$
    – user69935
    Commented Mar 2, 2020 at 20:54
  • $\begingroup$ So you have an atmosphere of at least -182 C (the evaporation point of oxygen). How dense do you envision that atmosphere being? If it’s anywhere near approaching the density of ‘space’ then the temperature of the atmosphere is less of an issue than the fact you can’t conduct heat through a vaccuum. $\endgroup$
    – Joe Bloggs
    Commented Mar 2, 2020 at 20:56
  • $\begingroup$ @JoeBloggs I am not so sure about the atmosphere density, some of the single cell life could expel necessary gasses to make the area more habitable $\endgroup$
    – user69935
    Commented Mar 2, 2020 at 20:59
  • $\begingroup$ (Sigh) Doesn't anyone read Larry Niven these days? For cold, see e.g. the Outsiders, who have a circulatory system based on liquid helium. And "The Integral Trees" depicts life in a ring system. $\endgroup$
    – jamesqf
    Commented Mar 3, 2020 at 4:35

2 Answers 2


My interpretation of space dangers is that the freezing temp is not your worst problem, it's the low pressure and radiation.

I think you can deal with cold and radiation in the same way, with a really impressive shell. Unlike in an atmosphere, in space you don't lose any heat from contact with cold matter (air or water or your mate's feet). You lose it all from infrared radiation coming off you. A thick shell of some very impressive substance, with various non-conductive layers, could prevent that (it's partially how a space suit works, after all). Also, if it is really radiation proof (or the anatomy is self repairing DNA), that helps there.

Pressure is tricky. You definitely don't want helium blood, because at lower pressure the liquid point is much much colder than on Earth (which is already super cold). If anything you want the opposite, some substance that is barely solid at room temp on Earth, which would be liquid at low pressure. I am sorry I do not have a substance to suggest. There is also the question of exploding, but when you think about how there are fish at the bottom of the Marianas Trench, we can see that internal systems can be adapted to massively different pressure levels, so as long as this thing never lands, it could work.


I was thinking of radiation as well - being the most dangerous thing in space. If you could have the creatures generate heat using the radiation, that would solve the cold problem.

As for propulsion... once you can generate heat you're basically set. All sorts of options for getting some of dem' kinetic energies.

A hyper-large infinitely-patient creature in space with the capability to move could do all sorts to get a story going.


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