Ive done some searching on this site and havent found very many people talking about Tardigrade's (water bears). If anything could survive on another planet or space in general i beleive these little guys would be the most likely canidate in my opinion. I already know that they can survive for days at tempuratures of -272.8 °C, and can stand radiation of 5700 grays of x-ray radiatoin when it would be fatal for humans at only 5 grays. If you have anymore info on the subject or any other critters you would like to bring up please do. im interested and would like to know more about other peoples opinions on this matter.

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Kiazer Whilhem 2 - "Till the world comes to a end, the final decision will rest with the sword."

They are amazing little things, I had the chance to study them in detail this summer during my time at Friday Harbor Labs. They're also extremely tolerant to desiccation (when it starts to happen, they undergo anhydrobiosis). If any metazoan could survive in space, they'd be the ones to bet the house on...

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Do not taunt Happy Fun Ball.

Extremophiles in general are very interesting, and suggset that life may exist in condition's very unlike that existing on most of the Earth's surface. Waterbears suggest (to me anyway) that complex multicellular life might also have a chance in extreme conditions.

But there is something else to consider; life emerged long ago on Earth, apparently by abiogenesis. The conditions which prevailed on Earth in that long ago time were very different to those existing today. There was no free oxygen, and a reducing environment; if we consider those conditions to be the norm for an Earth-like planet that would make our oxidising environment today seem extreme. In some ways we are the extremophiles.

On other planets life could start out under conditions resembling those on the early Earth, but could evolve to survive and thrive in a wide variety of other conditions. In some cases, like the Earth, the entire environment of the planet might be drastically changed by the presence of life.
However that doesn't necessarily mean that the conditions on a planet which has been drastically changed by the effects of its biosphere will exactly resemble those on Earth.

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Orion's Arm . The Starlark . Voices: Future Tense . OA Flickr set

True. However, my research experiences have convinced me that complex multicellular creatures as we know them (i.e., CHON life that lives by exploiting redox potential) could neither evolve nor exist without the availability of sufficient oxygen.

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Do not taunt Happy Fun Ball.

It's easy to overrate tardigrades. Yes, they can survive in unbelievably extreme conditions, but they can not function in them. A tardigrade must return to what we would consider a "benign environment" in order to become active, eat, and reproduce.

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Fiction has to be plausible. Reality is under no such constraint.

And they have to eat something as they don't make their own food.

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"The beauty of that discussion of averages is that you don't have to be an expert in Apollo or in photography in order to see where this time study "analysis" breaks down. You just have to be, well...not an idiot." -JayUtah