Saturday, September 8, 2012

Tardigrades Is the Animal Than Can Survive the Space

It said that life of Tardigrades (also known as Water bears) are interesting.  It is also said that they're one of the chosen few animals that can survive the space. Another interesting facts about this animals is that their survival ability is so awesome that they can return back to life after death.

So what are  Tardigrades?

According to wikipedia, Tardigrades are  very small,approximately they grow to a size about 1mm. They are also water-dwelling, segmented animals with eight legs. They form the phylum Tardigrada, part of the superphylum Ecdysozoa.

How They Can Survive the Space?

One way in which tardigrades have adapted to various types of environments, has been to reversibly suspend their metabolism. This state is known as cryptobiosis and is a truly deathlike state. Metabolism lowers to 0.01% of normal or is entirely undetectable and the water content of the body decreases to less than 1%. The environmental extreme determines which of four crypto biotic pathways -- anhydrobiosis, cryobiosis, osmobiosis, and anoxybiosis---will occur.

While in a state of cryptobiosis organisms are able to resist environmental extremes that would be instantly lethal to the animal if in the active state. In a review of cryptobiosis, Crowe (1971) discusses some of the findings regarding the abilities of tardigrades to withstand these environmental extremes. In the 1920's P. G. Rahm of the University of Freidburg discovered tardigrades were able to withstand being heated for a few minutes in 151 degrees Celsius and survive being chilled for days in temperatures up to minus 200 degrees Celsius. While in this state the organisms are also greatly resistant to ionizing radiation as shown by Raul M. May from the University of Paris who found that 570,00 roentgens were required to kill 50% of exposed tardigrades (only 500 roentgens would be fatal to a human). Water bears are also resistant to vacuums. Specimens exposed to high vacuum and electron bombardment in a SEM for 0.5 hours were then revived and survived for a few minutes before dying. Why are organisms in the cryptobiotic state able to withstand extreme conditions? Crowe (1971) hypothesized that the importance of water, heat, and oxygen in destructive reactions may explain why the lack of at least one of these characters in animals in cryptobiosis provides resistance to such cellular breakdown.

For further understanding about the Tardigrades, Watch this documentary video about the First Animal to Survives Space.


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