skolnick1 wrote:There are things that eat stone and CO2, man.
Some of them spit out oxygen.
I'd be interested to hear what they are; oxygen is relatively energy-consuming to make, and I haven't heard of any lithotrophs that bother. Most are rather dependent on oxygen. The ones that aren't still generally depend on some relatively strong oxidizing agent, like nitrate or sulfate, being present in the same environment as a reducing agent like hydrogen or ammonia. There's a reaction waiting to happen, and by catalyzing it they can enjoy the energy it gives.
But those reactions don't wait forever. On earth you get mixtures of reagents like that as a byproduct of the activity of other living things; for instance, decomposers produce sulfide in lower portions of lakes from compounds in dead bodies, and then there's a layer where it mixes with oxygen from the upper layers, which sulfur bacteria then exploit. But both the reducing and oxidizing agent are ultimately dependent on light energy to generate. Leave them together, and the sulfide would oxidize on its own.
Lots of people like to talk about the possibility of living things in oceans like Europa's, but I've never heard any plausible suggestion for how it would have stores of chemical reagents still available to them after millions and millions of years.
PolakoVoador wrote:And while some creatures are reliant on oxygen, there are some anaerobic ones around there too. Still reading the wiki article, bacteria from the Chlorobiaceae family use the faint glow from the black smoker for photosynthesis. That's a new one for me.
Anaerobes generally rely on energy from chemical compounds that other organisms, so I wouldn't assume they're truly independent of the sun either. The green sulfur bacteria using light from the vent could count, though. Thank you, I hadn't heard of them. I'm skeptical that would work be enough to have any Europaean life, but at least it's some