Originally Answered: Will tardigrades survive on mars?
Even their eggs if they are dried out first Tardigrade Eggs Might Survive Interplanetary Trip | WIRED
Though they hardly look like it - while moving about in water they look soft fragile creatures that you'd think would hardly stand up to anything: Tardigrade
Eggs:
Dried out tardigrade egg left - able to withstand temperatures from -320 up to 122 degrees Fahrenheit (-195 to 50 C ), vacuum conditions, and 1,690 Grays of radiation.
The mature tardigrades can survive -253°C to 151°C, as well as exposure to x-rays, and vacuum conditions. and a pressure of 600 MPa (almost 6,000 times atmospheric pressure at sea level), Life in Extreme Environments
They can survive in a dry state for 10 years (with one case of leg movement in a "revived" 120 year old specimen found in dry moss) Tardigrade | World Public Library
There also may be water on Mars in small quantities.
Main problem is, that they need a small percentage of oxygen. Would they find that on Mars? If not they enter anoxybiosis and soon die, within a few days, the state they enter in this case is not as resistant as the dessication state.
They look like this - their muscles relax, more water enters their bodies and their bodies swell. After a few days like this, without oxygen, they die.
Water bear (heterotardigrade), in the asphyctic state. See The Water Bear Web Base (monthly internet magazine) - Passing from anhydrobiosis via coma (asphyxis) to active life
Body length ca. 250 µm.However they would also need some food such as algae. And if there are algae on Mars, and lichens, then they may provide the oxygen needed. Some polar and high alpine lichens can survive in the Mars conditions - and the fungal part of the lichen is an aerobe, and it is able to survive in partially shaded conditions in Mars simulation chambers, no problem. So presumably it gets oxygen supplied to it by the algae component of the lichen.
So - could tardigrades survive on Mars in some niche habitat with sufficient algae in it to provide oxygen? Or in association with lichens occasionally moistened by water?
I don't know, not seen a study of this and can't find one just now, but can't see really why not. That is if these habitats exist and if they are populated by lichens and algae to provide some oxygen (I don't think they need large amounts of oxygen though I can't just now find a figure for the minimum % they need, if anyone knows do say).
They are rare in Antarctica but have been found there:
Page on discovermagazine.com. Also, they are found in some habitats in the Atacama desert Microbiology of Extreme Soils
But - I don't think they are commonly found in the nearest equivalent to the suggested Mars habitats on Earth such as the McMurdo dry valleys or the heart of the Atacama desert.
Often the only organisms listed are micro-organisms. It might be the same on Mars, where it would be even more of a challenge for them with hardly any oxygen in the atmosphere.
They couldn't survive on the surface, just on the night time humidity, like the lichens, because they need water around them to survive. And they need something to eat as well, aren't primary producers like the lichens and algae, so that's restrictive as well, need a habitat with enough life in it to sustain them.
But what about the possible habitats on salts / ice interfaces? Just a few mms of water chances are, but a tardigrade is of the order of - well that photo above is 250 microns - a quarter of a millimeter.
There - possible habitats include the warm seasonal flows - if there is enough water flows there - or the droplets on salt / ice interfaces - or subsurface deliquescing salts which may be a few mms thick, or salt towers - or the flow like features in the upper lattitudes near the poles where water may melt below the surface of clear ice if they have the equivalent of Antarctic "blue ice" on Mars. Some of those melt water habitats, if they exist, could be at 0C below an overlying layer of ice in the solid greenhouse effect and could be up to tens of cms thick in some of the models in the most ideal situation, immediately above a layer of rock that absorbs heat from the sun (that is, if this Martian equivalent of blue ice exists, which is not yet known).
There's also the chance of hydrothermal features sustained by geothermal heating from below.
Could they survive in any of these places? It seems a huge challenge even for them. But is it impossible?
Interested to know if anyone else has anything on this!
WHAT ABOUT OTHER MULTICELLULAR LIFEFORMS
Oh, and you may be interested in the more general question of whether there could be multi-cellular life, and other miniature multi-cellular animals on Mars.
So first of all multi-cellular life in the form of lichens, very possible, because of the DLR (German Aerospace) experiments. Surviving the conditions on Mars
Pleopsidium chlorophanum collected at an altitude of 1492 m above sea level at "Black Ridge" in North Victoria Land, Antarctica. This lichen lives at altitudes of up to 2000 meters in Antarctica.
It can remain active at very low temperatures, down to -20 C and can absorb small amounts of water from snow and ice. In a 34 day experiment, it continued to photosynthesize, and it adapted to Mars conditions and even adapted physiologically by increasing its photosynthetic activity, and producing new growth http://www.researchgate.net/prof...
http://bit.do/44Uk
Also stromatolites, very ancient on the Earth,
These could have formed on Mars in its ancient oceans. Not likely to still be there today. But there could be complex "biofilms" where you have a community of many microbes together forming structures. Not quite multi-cellular. But might create structures you can see, not just microscopic.
As well as that we have anaerobic lifeforms on the Earth, animals that don't use oxygen for any part of their life cycle. These tiny mm scale Loricifera
The purple colour here is a stain, not its natural colour File:Spinoloricus.png - Wikimedia Commons
They do it by relying on Hydrogenosomes instead of mitochondria for energy.
So - not suggesting that there are Locifera on Mars, not heard anyone suggest that. But it suggests you can have multicellular animals that don't depend on oxygen on Earth. So could there be animals not using oxygen on Mars also, perhaps using some other mechanism?
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
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