Tardigrades (TAHR-di-greyds), often called water bears, are near-microscopic animals with long, plump bodies. They have eight legs, with four to eight claws on each. While strangely cute, these tiny animals are almost indestructible.
Water bears can live in just about any type of water body. They prefer to live in sediment at the bottom of a lake, on moist pieces of moss or other wet environments. They can also survive a wide range of temperatures and situations.
Researchers have found that tardigrades can withstand environments as cold as -200˚C (-328°F) or highs of more than 149˚C (300°F). They can also survive radiation, boiling liquids, massive amounts of pressure (up to six times the pressure of the deepest part of the ocean), and even the vacuum of space, without any protection. A 2008 study found that some species of tardigrade could survive 10 days at low Earth orbit while being exposed to space vacuum and radiation.
In many conditions, they survive by going into an almost death-like state called cryptobiosis. They curl into a dehydrated ball and can come back to life in just a few hours when reintroduced to water. In 2016, scientists revived two tardigrades that had been in cryptobiosis for more than 30 years.
