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regular_modern_girl t1_it54440 wrote

Reply to comment by molbionerd in Why does alcohol kill bacteria, but not the cells that our bodies are composed of? by Chairman_Mittens

this is admittedly really pedantic (although this might actually be more of a popular misconception than I’m thinking), but technically water bears can actually survive (at least in terms of like, actually actively living in) only in a fairly narrow range of conditions, requiring freshwater aquatic habitats in a fairly moderate temperature range (they can live in extremely thin films or tiny droplets of water in otherwise terrestrial environments, but that’s about the most extreme they get when actually living, breathing, eating, and mating), it’s more that they can enter a state of cryptobiosis (called a “tun”) which is incredibly resilient to extremes, up to and including the conditions of outer space or near-absolute zero temperatures (and then having their frozen tun state used in a quantum double-slit experiment, and still being successfully revived after lol).

So with water bears it’s more that they’re really good at weathering extremes, but not necessarily actually living in them per se, whereas bacteria and archaea can often actually exhibit active cellular metabolism and other processes even in some really extreme habitats.

I mostly just mention this because I’ve seen a lot of people say that water bears are “extremophiles”, when really they’re actually somewhat on the fragile side while actively alive, they just have a very resilient hibernation-like state they can enter, basically.

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molbionerd t1_it56pbc wrote

Yes they are not actively growing in those environments, but as long as they can return to that active state, they are alive. Many organisms (especially “simple” organisms like bacteria and lower eukaryotic life) are able to enter these non-metabolically active states, sometimes with extra protection (like the water bears, spore forming bacteria, and lots of fungi and yeast) allowing them to survive those extreme conditions. Arguably this is ability is more interesting and without a doubt it’s more important for the survival and dissemination of life across earth, and potentially across the universe. We may have already spread them ourselves :)

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TrogdorLLC t1_it5k5uk wrote

They are already on the Moon, thanks to an Israeli lunar probe that crashed there.

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Quantum-Carrot t1_it6md6p wrote

I watched that stream live. That thing must have hit the moon at like 500 km/h. Maybe some of the ejecta will land on another planet?

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Misterbellyboy t1_it7wamp wrote

Isn’t that why permafrost melting in places like Siberia could be kind of alarming? A bunch of hibernating prehistoric bacteria that we’ve never had to deal with before “waking up” again or something like that?

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