Tuesday, March 14, 2006

Tardigrades: Earth's toughest organisms?

Forget cockroaches, tardigrades (Kingdom - Animalia, Phylum - Tardigrada, Common name - Water Bear) are probably the world's hardiest creature, and they're cute! Tardigrades were first discovered in 1773, since then about 400 distinct variations have been identified.

Tardigrades inhabit semiaquatic environments, sometimes in numbers exceeding 1.5 million per square meter.

They range in size from .1 to 2mm long. They have eight legs, each with clawed toes. Tardigrades move with a slow, lumbering gait, hence their common name. The name 'tardigrade' comes from the Latin 'tardus', meaning 'slow', and 'gradus', meaning 'step'.

- Tardigrades can survive being heated for a few minutes to 151°C or being chilled for days at -272.8°C (nearly absolute zero).

- Tardigrades can withstand 5700 'grays' of x-ray radiation. (Five grays and a human is toast).

- Tardigrades can weather the nearest thing we can simulate to a vacuum right through to 6,000 times atmospheric pressure.

Tardigrades' immense resilience stems from their ability to slow their metabolic activity to a crawl, a phenomenon called anabiosis. When conditions become even more extreme, they employ a 'near death' stage of dormancy called cryptobiosis. During these periods tartigrades secrete envelopes around their bodies known as tuns.

Tardigrades can survive in their tuns for an indefinite period of time. Museum workers who moistened a 120 year-old dessicated moss sample found living tartigrades within hours.

Tardigrades feed upon detritus, fresh plant material and smaller invertebrates.

Fascinating fact to throw into a lagging conversation: The true (although not so cute) King of Radiation is the foul-smelling red-coloured bacterium Deinococcus Radiodurans (nicknamed 'Conan the Bacterium' by its admiring researchers). It was discovered in irradiated canned meat that had still managed to 'go bad'. This plucky bacterium happily grows in 1,500,000 rads of radiation - and, if frozen, over 3,000,000 rads!


Sky Jordan said...

Those are so cool! I wants one, can I have one? Please daddy, please? *angelic, puppy eye look*

brett jordan said...

Hi Sky, of COURSE you can have one. Just pay a visit to any student kitchen, there'll be about a zillion of them swimming around in the unwashed dishes and cutlery.

Teifion said...

I'll send you some if you want, we should have loads in our kitchen

brett jordan said...

Thanks for the generous offer Teifion, but, on this occasion, I'll take a rain-check :-)

Anonymous said...

I bet Jack Bauer could take more than a Tartigrade.

brett jordan said...

Re: Jack Bauer...


whoever you are!

Sky Jordan said...

Re: teifion
Thank you muchly. Had it pointed out I'll need a "make bigger" machine, so if you have one of those handy it'd be much appreciated!

Skep said...

Fascinating... absolutely fascinating... although you should've known by the "bear" part that this little thing was going to be tough as all-hell.

Andy. said...

Not a bad article, but it's spelled tardigrade, not tartigrade... check those latin roots!

brett jordan said...

Thanks Andy, corrections duly made.


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