Tardigrades, popularly known as Water Bears, are microscopic invertebrates in the animal kingdom that are almost indestructible. They are 0.1 to 1.5 mm long and thrive in moist conditions and are abundantly found on lichens and mosses. They have segmented body with four segments and four pairs of legs without joints, one pair in each segment, with tiny claws and even eyes. They are real animal.
They are spread over the globe from high snow capped Himalayan region (6000mt) to sea depth of 4000 mt and from polar to equator regions. They can survive extreme conditions like temperatures up to 150C (300F) or down to nearly absolute zero, absorb1000 times more radiation than any other animals and remain alive a decade without water. They can withstand pressure around 6000 atmospheres and even the vacuum of space.
According to a report in New Scientist, in a study led by Ingemar Joensson of Sweden’s Kristianstad University, two species of 3000 dried up tardigrades were put abroad a European Space Agency Spacecraft FOTON-M3 from Kazakhstan in September’2007 and exposed to 10 days in vacuum of open space. After retuning, the tardigrades were rehydrated and tests were carried.
"Our principal finding is that the space vacuum, which entails extreme dehydration, and cosmic radiation were not a problem for water bears. On the other hand, the ultraviolet radiation in space is harmful to water bears, although a few animals can even survive that," said Joensson.
In one of the two species tested, 68% of the sample shielded from UV radiation survived within 30 minutes of being rehydrated and even went on to lay eggs that hatched successfully.
However only a handful survived the sun’s full UV exposure, which is 1000 times greater in space than on earth. Joensson suspects that even the survivors suffered DNA damage from radiation but ‘mysteriously’ repaired their genetic material. Figuring out the mechanism of this self-repair may benefit medical science.
Explaining further he said, “One problem of treating human cancer is that radiation therapy damages healthy cells also. If we can find that there are molecules involved in DNA repair in multicellular animals like tardigrades, we might be able to further the development of radiation therapy (to treat cancer better).”