If Titan's hydrocarbon seas were seeded with tardigrades, would the tardigrades survive and thrive?
No, the surface temperature is much too cold and there is nothing for them to eat. Tardigrades are only able to survive at the 94 kelvin of Titan's surface in a sort of "hibernation" state and would die after a few days.
Tardigrades require oxygen for respiration - the atmosphere on Titan is primarily nitrogen and methane, with other hydrocarbons. No oxygen as far as is known.
I dont think Tardigrades would survive, but you can always assume a life form which needs liquid methane except water to survive, and needs other chemicals to live.
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