Let's create an alien biosphere!

[MathAndCode]

Do you think we need some sort of chemical infrastructure for the digestion of other organisms?

I don't think that it will be very difficult at first. Because the potential prey will not have evolved to resist predation, it's merely a matter of getting the methane from the photosynthesizers, which can be done by piercing their membranes or simply making it more porous is therefore doesn't seem like a complicated thing to evolve.

[Schiaparelliorbust]

I don't think that it will be very difficult at first. Because the potential prey will not have evolved to resist predation, it's merely a matter of getting the methane from the photosynthesizers, which can be done by piercing their membranes or simply making it more porous is therefore doesn't seem like a complicated thing to evolve.

So you don't think they should engulf each other but just steal what they're making/using.

[MathAndCode]

So you don't think they should engulf each other but just steal what they're making/using.

They will likely engulf each other eventually, but they likely won't at first.

[Schiaparelliorbust]

They will likely engulf each other eventually, but they likely won't at first.

I guess resistance will likely evolve soon. How might it manifest itself?

[MathAndCode]

I guess resistance will likely evolve soon. How might it manifest itself?

One option is for photosynthesizers to expel reactive oxygen species when they sense a predator nearby.

[Schiaparelliorbust]

One option is for photosynthesizers to expel reactive oxygen species when they sense a predator nearby.

Hydrogen peroxide might be possible.

[MathAndCode]

Hydrogen peroxide might be possible.

Yes, that's one possibility.

[Schiaparelliorbust]

Yes, that's one possibility.

Can it be neutralized in some way? I don't want to cause an evolutionary arms race or anything; the only way I can think around a neutralizer is producing more peroxide, which has its limits.

[MathAndCode]

Can it be neutralized in some way? I don't want to cause an evolutionary arms race or anything; the only way I can think around a neutralizer is producing more peroxide, which has its limits.

Yes, our cells have ways to neutralize reactive oxygen species, including peroxide. Of course, the organisms on the alien planet wouldn't have to use the exact same methods, and the fact that organisms start producing oxygen relatively early would likely cause life to evolve to use biomolecules that tend to be less vulnerable to dioxygen and reactive oxygen species.

[Schiaparelliorbust]

Yes, our cells have ways to neutralize reactive oxygen species, including peroxide. Of course, the organisms on the alien planet wouldn't have to use the exact same methods, and the fact that organisms start producing oxygen relatively early would likely cause life to evolve to use biomolecules that tend to be less vulnerable to dioxygen and reactive oxygen species.

Could they evolve to synthesise and use ascorbic acid or other antioxidants?
Edit: Alpa and beta carotene, manganese and iodide can be used too.

[MathAndCode]

Could they evolve to synthesise and use ascorbic acid or other antioxidants?
Edit: Alpa and beta carotene, manganese and iodide can be used too.

Yes.

[Schiaparelliorbust]

Yes.

Which ones might they be more likely to evolve to use? Manganese, iodide and alpha/beta carotene are simple, I don't know about ascorbic acid.

[MathAndCode]

Which ones might they be more likely to evolve to use? Manganese, iodide and alpha/beta carotene are simple, I don't know about ascorbic acid.

I wouldn't worry about which specific compound they'll use first. They probably will evolve multiple defenses anyway.

[Schiaparelliorbust]

I wouldn't worry about which specific compound they'll use first. They probably will evolve multiple defenses anyway.

Yeah, you're probably right. Might there be a niche that scavenges the carcasses of the killed (or just dead) microorganisms?

[MathAndCode]

Yeah, you're probably right. Might there be a niche that scavenges the carcasses of the killed (or just dead) microorganisms?

Predators could potentially evolve from scavengers, or scavengers could potentially evolve from predators.

[Schiaparelliorbust]

Predators could potentially evolve from scavengers, or scavengers could potentially evolve from predators.

I would say the former is more likely, beasue there would always have been dead biomass and being a predator is a much more deliberate lifestyle.

[MathAndCode]

I would say the former is more likely, beasue there would always have been dead biomass and being a predator is a much more deliberate lifestyle.

Yes, I agree.

[Schiaparelliorbust]

Yes, I agree.

I just thought of something. Oxygen would also let life have a much more active aerobic lifestyle.

[MathAndCode]

I just thought of something. Oxygen would also let life have a much more active aerobic lifestyle.

Yes because they could unlock more chemical energy.

[Schiaparelliorbust]

Yes because they could unlock more chemical energy.

Are we done with the effects of oxygen now?

[MathAndCode]

Are we done with the effects of oxygen now?

Yes, I think so.

[Schiaparelliorbust]

Yes, I think so.

So on to early predation then? Or maybe simple sponge like multicellular organisms?
(Sponges are the simplest multicellular organisms.)

[MathAndCode]

So on to early predation then?

Won't the predators evolve from scavengers?

[Schiaparelliorbust]

Won't the predators evolve from scavengers?

Yes, but I meant multicellular predation. But I guess we don't wven havr anything of the sort, so forget that I said that. Sorry. What do you think of the sponge-like multicellular organisms?
Edit: We would have to provide aome incentive for multicellularity first actually.

[MathAndCode]

Yes, but I meant multicellular predation. But I guess we don't wven havr anything of the sort, so forget that I said that. Sorry. What do you think of the sponge-like multicellular organisms?
Edit: We would have to provide aome incentive for multicellularity first actually.

I suspect that the sulfate-reducing (and soon oxygen-reducing) organisms will form colonies around the hydrothermal vents. I think that we have already agreed that when a unicellular organism is approached by a predator, it will excrete reactive oxygen species in order to deter it. Perhaps the organisms will evolve to also release reactive oxygen species when a nearby organism is approached by a predator, and this will develop into more complex signalling pathways that eventually allow the cells to cooperate more efficiently as a multicellular organism.