The half-millimetre animal that survived the vacuum of space.
Tardigrades, or 'water bears', can dry out, curl into a husk called a tun and wait. In 2007 scientists sent some into orbit and exposed them to open space. Many came back, rehydrated and went on to lay eggs.
Tardigrades are eight-legged micro-animals, usually under a millimetre long, that live almost everywhere: in moss, leaf litter, ocean sediment and mountain streams. Under a microscope they look like tiny, chubby bears clambering through a droplet, which earned them their nickname.
Their fame comes from what they can survive. When their surroundings dry out, many species pull in their legs, lose almost all their water and shrink into a dormant ball called a tun. Their metabolism slows to almost nothing, a state called cryptobiosis. In this form they can tolerate extreme cold, high doses of radiation and pressures that would kill almost anything else, then revive when water returns.
In September 2007, the European Space Agency's FOTON-M3 mission carried dried tardigrades into low Earth orbit and exposed them to the vacuum of space for ten days. Back on Earth, many rehydrated and later produced viable offspring. Those that were also exposed to the Sun's full ultraviolet radiation fared much worse, but some still survived.
Part of their secret lies in unusual proteins. Some tardigrade proteins appear to form a glass-like matrix that holds cell contents in place as they dry, and one, called Dsup, seems to shield DNA from damage. Researchers are studying these molecules for ideas about preserving vaccines and medicines without refrigeration. Tardigrades are tough, not invincible: they are still vulnerable when active, and most live only a few months. Their trick is knowing when to stop living and wait.
Source: Wikipedia — Tardigrade · Text summarised from Wikipedia (CC BY-SA 4.0)
