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?