Tardigrades. Water Bears. Moss piglets. Whatever you choose to call them, they’re built like tanks. Pop culture has taught us that they’re seemingly indestructible and impervious to… just about anything. After all, they’ve been found living near vents on volcanoes, and have even survived the vacuum of space for a week and a half, where the sun’s UV radiation is 1000 times as intense as it is here on Earth.
If you’re not familiar with them, here’s a video that is a pretty good primer on these plushy bois:
But surely, tardigrades die sometime, right?
Of course! But the answer to that question isn’t as straightforward as you might think. The best answer is “it depends.”
Typically they live somewhere between 3 months and 2.5 years. But what’s really neat about these guys is that they can go into a state called “cryptobiosis,” meaning they lower their metabolic state to a point where it’s not detectable. Basically, they’re dehydrated and not much is happening with them, biologically speaking.
Think of it as tardigrade hibernation – tardibernation!
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Cryptobiosis puts tardigrades into a “tun” state, slowing their metabolism to a halt, reducing their need for oxygen and ridding their cells of water almost completely, according to the Encyclopedia Britannica. In this shrunken state, tardigrades mimic death so closely that they’re able to survive in places devoid of water, at temperatures as low as minus 328 degrees Fahrenheit and as high as 304 degrees F (minus 200 Celsius and 151 degrees C). When these mummy-like tardigrades are exposed to water again, they simply reanimate, returning to normal life in a matter of hours.
“So long as the tardigrade can get into the tun, it will cope with anything that you throw at it,” McInnes told Live Science.
And one study found that a marine tardigrade genus (Echiniscoides) will alternate between active and
tardibernation inactive states every six months, which may be responsible for extending their lifespans by a matter of decades.
But what exactly is it about tardigrades that makes them able to survive such hostile environments?
Good question! Scientists don’t really know yet. LiveScience.com reported:
“We are literally just scratching the surface of the biochemistry, the molecular pathways by which these animals cope with these environments,” McInnes said. For instance, along with being frozen, boiled and dried, it’s known that tardigrades can withstand pressures of up to 87,000 pounds per square inch (600 megapascals) — six times what you’d experience at the bottom of the sea. Just half this pressure would kill most other organisms on Earth.
It’s important to remember that not all tardigrades survive these environments, though. Some die while being boiled, frozen, blasted by UV radiation in the vacuum of space, and under immense water pressure. But the fact that some survive is remarkable. This means that if a cataclysmic asteroid impact wiped out all life on Earth, if the supervolcano in Yellowstone finally erupts, or if our President is successful in baiting North Korea into starting World War 3, the tardigrades at the bottom of Mariana Trench (where the pressure is more than 1000 times that of on the surface of Earth) will survive.
To quote the great scientist Dr. Ian Malcolm: