A tardigrade (also waterbear) is a microorganism of the phylum Tardigrada. Water bears have four pairs of legs and live in water, most often in lichens and mosses. Adults range in size from 1.5 mm to below 0.1 mm. They are famed for their ability to survive in harsh environments by entering an anabiotic state known as the "tun state." When experimentally dessicated for a decade or more they have been rehydrated and showed no ill effects. They can tolerate 1,000 times as much ionizing radiation (gamma rays and heavy ions) as a human being. They have also survived boiling, deep freezing to temperatures as low as 1° Kelvin, and exposure to the vacuum. With these characteristics, they are often cited as organisms that could plausibly colonize new planets by surviving the adverse conditions of outer space.
|
|
