Is there any life on Earth that does not need H2O?

Perhaps an extremophile? I think not, I found reference to one that needs an extremely small amount of water, but it still needs some.


It depends on how you define “life”. Are viruses alive? They require living cells to replicate, and all living cells require water, but I believe that viruses can survive in a kind of suspended anination for many (hundreds?) of years without any water whatsoever.

Are viruses considered “living organisms” by most biologists?

According to WikiAnswers,

However, I doubt that it exists without water from other sources; it just doesn’t drink it. That’s not what you meant, is it?

Even virus particles have water of hydration on their protein coats,

There are bacterial spores that can survive extreme dehydration, but they’re dormant - they’re not growing or reproducing.

I’ll bet even the bacterial spores have a minimal amount of water. Proteins have a tendency to unravel without hydrating water. Just ask anybody that has tried to get a crystal structure of a protein.

Well Revtim,seeing how my ex-wife qualifies as an organism the answer is “yes”. Man,…she was one dead fish.

Here … this is probably the mosthard ass extremophile.

And yet, I’ll bet there is still some water surviving in that organism after exposure to space.

That freaks me the hell out. If that’s feasible on earth as a niche evolution, imagine an alien ecosystem that revolves around those kinds of conditions :eek:

I for one welcome our interstellar traveling Bug Overlords :o

Kangaroo rats can exist without ever imbibing water. They are capable of making all their own water from starch and sugar.

The point to remember is that starch is made by plants combining water and carbon dioxide via the addition of energy in the form of sunlight and excreting oxygen. Us animals just reverse the process: we use oxygen to split the sugars into water and carbon dioxide and remove the energy that is released.

Most animals, including us humans, can’t actually gain water in this way, because the need for more oxygen means that we breath more, and we lose more moisture in our breath than the digestion provides in the first place. But kangaroo rats have some clever mechanisms to ensure that they don’t lose much moisture in their breath. So they can live out their entire adult lives without ever taking in any water.

Plenty of other small mammals can do this too, including common house ice. However for house mice this is a real knife edge existence, and they invariably die of dehydraton if fed a dessicated diet. However they will usually last several weeks or even a few months before they succumb, and after an initial weight loss their body weight stabilises for some time before it begins to fall again, which indicates that they do indeed manage to gain all their required water metabolically. The problem seems to be that they just can’t sustain it indefinitely, though nobody is sure why.

However kangaroo rats, and quite a few other desert rodents, can sustain it from the moment the are weaned until they die of old age. So in that sense these animals don’t need water.

Now if the OP is asking whether any animals contain no water, then the answer is a definite “No”.

One kind of bacterium lives in sulfuric acid and needs no air, no oxygen.

I know there is an alge that lives in diesel oil.

Kangaroo Rats, as mentioned above, do not need to drink water. In addition, there’s a vaguely related rodent-like species native to east asia called the mogwai which don’t drink water. (In fact, water actually causes them problems).

Koala bear? I think gets its water from leaves and does not ever drink

Just to clarify, I didn’t mean “doesn’t drink to obtain H20”, but “does not need H20”.

Isn’t that the animal that eats, shoots and leaves?

According to the article, the acid in question is formed from rainwater; it’s unlikely we’re talking about pure H2SO4, but rather a dilute water-based mxiture of same. It’s unclear whether the bacteria do or do not require H2O for their metabolism.

Algae does not live in diesel fuel..

There are bacteria that can feed on diesel fuel, but according to Wikipedia, these bacteria exist at the boundary between diesel fuel and water - which suggests that water is necessary to their metabolism.