Water bear (tardigrade), Hypsibius exemplaris, scanning electron micrograph by Bob Goldstein and Vicky Madden.
The Indestructible Micro-Survivor
Under a microscope, tardigrades look like plump, eight-legged gummy bears wandering across moss cushions. Despite measuring under a millimeter long, they are the toughest animals on Earth. When environmental conditions turn hostile, they pull in their legs, expel virtually all cellular water, and enter a state called a “tun.”
Bio Fact: In 2007, dehydrated tardigrades were launched into low Earth orbit and exposed to the open vacuum of space and cosmic solar radiation for ten days. Upon return to Earth, rehydrated tardigrades woke up, laid eggs, and continued living normally.
Defying the Laws of Physics
In their cryptobiotic state, tardigrades can withstand temperatures down to -272°C (just one degree above absolute zero) and heat up to 150°C. Unique intrinsically disordered proteins create a glass-like matrix inside their cells, locking delicate DNA and membranes into place until moisture returns.
