Wednesday, November 6, 2013

King of the extreme


Extremophiles are lifeforms that can live or survive in extreme environments. Such environments can be defined by temperature (extreme hot or cold), acidity, salinity, pressure (high pressure or space vacuum), presence or absence of chemicals, radiation...

For example, some bacteria can survive in boiling water. Some insects can survive radiations thousands of times more intense than what would kill humans. Some ticks can survive space vacuum.

Surviving 1 extreme condition is strange. But surviving 2 extreme conditions is radical. This is what we call "polyextremophiles". What about organisms that can survive 3 extreme conditions? Or 4? Or 5? They bring us to a whole new different way of thinking about life itself. Some bacteria can survive cold, dehydration, vacuum, and acid.

But there's 1 animal that takes the cake. One animal that could potentially achieve the impossible: the tardigrade.

The tardigrade

 It doesn't look like much. It looks like any kind of bug or acari. But let's look at what it can endure:

  • extreme cold:
    • 1°K for a few minutes (-273°C or -458°F)
    • 73°K for a few days (-200°C or -328°F)
  • extreme hot:
    • 151°C or 304°F for a few minutes
  • extreme low pressure: space vacuum + solar radiation for more than 10 days
  • extreme high pressure: between 1200 and 6000 atmospheric pressures
  • dehydration: for over 10 years
  • radiation: between 5000 and 6000 Gray (=1000 times more resistant than humans)

Due to these surprising characteristics, tardigrades interest astrobiologists. By studying these animals, their genome, and the mechanical, physical or chemical reasons for its resistance especially in space, there is hope that we can gain knowledge that will prove useful in the future of mankind as we start leaving the Earth for establishing colonies on other planets or as we send entire societies to live and travel in giant space ships towards new solar systems (OK, I admit: I love science-fiction).

What's even more surprising regarding the tardigrade, beyond the fact that it is a polyextremophile, is the fact that its resistance goes much beyond conditions that can be found on Earth. For example: its resistance to high pressures extends to pressures 6 times higher than the pressure that exists at the bottom of the deepest oceanic trench. The extreme cold temperatures that it can endure are without comparison with the coldest temperatures ever recorded anywhere. To put things in perspective: it can live for a few days in temperatures colder than liquid nitrogen!

It would be tempting to imagine that unearthly resistances like these must arise in unearthly conditions. But no! The tardigrade is definitely a creature from Earth that finds its place in the tree of life that all lifeforms share on this planet. However, it is very weird.


You discovered the existence of a fun creature!

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