![]() Īs mentioned earlier, there has been a flurry of journalistic activity related to tardigrades lately, starting at the beginning of the month. Challenging for astronauts, but perhaps no so much so far tardigrades, then. Now, the Moon has extreme temperatures, very low humidity, and elevated radiation levels. ![]() However, as of 2001, these laboratory results have yet to be verified. Environmental toxins – tardigrades are reported to undergo chemobiosis, a cryptobiotic response to high levels of environmental toxins.No eggs irradiated at the early developmental stage hatched, and only one egg at middle stage hatched, while eggs irradiated in the late stage hatched at a rate indistinguishable from controls. The eggs were more tolerant to radiation late in development. Irradiation of tardigrade eggs collected directly from a natural substrate (moss) showed a clear dose-related response, with a steep decline in hatchability at doses up to 4 kGy, above which no eggs hatched. However, subsequent research found that tardigrades, when hydrated, still remain highly resistant to shortwave UV radiation in comparison to other animals, and that one factor for this is their ability to efficiently repair damage to their DNA resulting from that exposure. The only explanation found in earlier experiments for this ability was that their lowered water state provides fewer reactants for ionizing radiation. Radiation – tardigrades can withstand 1,000 times more radiation than other animals, median lethal doses of 5,000 Gy (of gamma rays) and 6,200 Gy (of heavy ions) in hydrated animals (5 to 10 Gy could be fatal to a human).As water expands upon freezing, dehydration ensures the tardigrades’ tissues are not ruptured by the expansion of freezing ice. When exposed to extremely low temperatures, their body composition goes from 85% water to only 3%. Dehydration – the longest that living tardigrades have been shown to survive in a dry state is nearly 10 years, although there is one report of leg movement, not generally considered "survival", in a 120-year-old specimen from dried moss. ![]() ![]() Some species can also withstand pressure of 6,000 atmospheres, which is nearly six times the pressure of water in the deepest ocean trench, the Mariana Trench.
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