At least 30 years
There are over 1,000 species of water bear (phylum: Tardigrades). They are found practically everywhere in the world, as long as there is moisture. What makes them so remarkable is their extraordinary capacity for survival. They can withstand just about anything. Temperatures between −272˚C and 150˚C, pressure six times greater than in the Mariana Trench (the deepest location on Earth), annihilating radiation and the vacuum of outer space. Even during extreme drought they can survive at least 30 years by drying themselves out. Researchers at the University of North Carolina (US) made a remarkable discovery about this very dehydration process.
Anhydrobiosis
‘By retracting its eight legs and head into its exoskeleton, the water bear forms a tiny ball and survives the total dehydration of its body from extreme dryness’, said principal researcher Dr Thomas Boothby in a press release. This process is also known as ‘anhydrobiosis’. ‘The water bear can survive in this state for years, even decades. And when you put it back in water, it wakes up within a few hours. They are back to running around, eating and reproducing as if nothing happened.’
Breakthrough
For years, researchers believed that water bears used a sugar called trehalose, the same substance that brine shrimp use to protect themselves against dryness. Previous research already called this theory into question. It turned out that the amount of trehalose in the water bears in a desiccated state was much lower than in dehydrated brine shrimp. In the scientific journal Molecular Cell, Dr Boothby’s team explain that water bears indeed do not dry themselves out using trehalose. The researchers discovered that water bears have a special set of genes which code for the production of ‘tardigrade-specific intrinsically disordered proteins’ or TDPs. These proteins protect the water bear’s cells during dehydration.
Glass-like structure
As soon as dehydration starts, the water bear activates the TDPs. The effect of these proteins closely resembles that of trehalose in brine shrimp. The proteins envelop the molecules in the cell in a glass-like structure that allows the molecules to retain their shape during the extreme dryness. ‘This slows the water bear’s metabolism and it goes into a kind of state of hibernation until there is water’, Boothby explains. The water melts the proteins and the molecules can resume their function.
Source: Molecular Cell