"The dehydrated tardigrades withstand a wide range of physical extremes that normally disallow survival of most organisms, such as extreme temperatures, high pressure, immersion in organic solvent, exposure to high dose irradiation and even direct exposure to open space," wrote lead author Takuma Hashimoto of The University of Tokyo and colleagues.
"Space" refers to the vacuum of outer space, so even NASA is interested in water bears because they suggest that life could be possible in the extreme conditions of other planets.
To determine why water bears are near indestructible, Hashimoto and his team conducted a genetic analysis on one of the most stress tolerant tardigrade species: Ramazzottius varieornatus. It is the toughest of the tough in the animal kingdom.
The researchers identified a unique water bear protein that suppresses X-ray induced damage by about 40 percent in human cultured cells. It also made human cells more tolerant of radiation. Those findings open up a whole new line of research on the water bears' proteins , which could prove to be very beneficial to humans.
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The research also presents the first ever genome sequence for an "extremotolerant" tardigrade. As that descriptor indicates, these animals can again survive almost anything.
It is especially impressive that they can live through being dried to a crisp. Novelty aquarium pets known as Sea Monkeys, which are actually brine shrimp, have a similar ability. When desiccated, these brine shrimp go into a different state of being called cryptobiosis or anhydrobiosis. It's a condition of apparent lifelessness that allows survival, even when the temporary water pools in which the brine shrimp live in the wild dry up.
Microscopic water bears live in almost every place on Earth. They can be found in leaf litter and soil, beaches, dunes, fresh and salt water, and even in the slimy film of water that collects on lichens and mosses.
A water bear walking on moss: