Tardigrades or "Water bears" are the only creatures that can survive the extreme conditions in the vacuum of outer space.
Beginning in 2007, biologists sent these little suckers up to the space station (along with other so-called extremophiles) and found that tardigrades can survive the vacuum of space and the life-zapping radiation of the sun. Other experiments have shown that adult tardigrades can survive both extreme pressures and temperatures, ranging from -459 degrees Fahrenheit up to 300 degrees Fahrenheit. Even if recent DNA and RNA sequencing show that tardigrades are the sister group to arthropods and Onychophora, their evolutionary lineage is unclear. Some have even theorized – cue the X Files music – that tardigrades came from another planet, and rode to Earth on space debris.
Their secret? The little water bear is one of few groups of species that are capable of reversibly suspending their metabolism and going into a dehydrated state called cryptobiosis. In this kind of suspended animation, a tardigrade’s metabolism lowers to less than 0.01% of normal, with water content dropping to 1% of normal. No wonder they’ve got staying power: some 1,150 species of tardigrades have been described throughout the world, and they’ve been found to live virtually everywhere, from the Himalayas (above 20,000 feet), to the deep sea (below 13,000 feet) and from the polar regions to the equator.
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