Water bears go where no animal has gone before
October 28, 2010 2 Comments
Timeline, 2008: They say that in space, no one can hear you scream (or at least that Alien movie said it). The reason for that is that sound waves require matter to be propagated, and in the vacuum of space, there is no matter. Hard as your vocal cords may push, they can’t make the sound travel through nothing.
That vacuum carries other complications for people beyond an inability to chat unprotected. Space is cold—temperatures run close to absolute zero, or -272 Celsius. With the vacuum, there is no oxygen and no pressure. And let’s not forget the bombardment with deadly cosmic rays and, if you’re hanging around just above Earth, UV rays 1000 times more powerful than those we experience on terra firma.
Boiling saliva and bubbling blood. Ewww.
Thus, if you send person or a dog or an ape unprotected into space, within minutes, the lack of pressure would lead to an uncomfortable death involving boiling saliva and bubbling blood. Yet, there are organisms known to survive the environment of space, primarily some bacteria and lichen, the symbiotic combination of algae and fungus. Now, we’ve learned that a little critter that lives on lichen also can be quite the intrepid space traveler.
Water bears–not even remotely like bears
The space animals—the first animals, in fact, known to pull off unprotected space travel—are representatives of two species of tardigrades. There are up to 1000 species of these little animals, more familiarly known as “water bears” because of their rotund, bear-like appearance. Researchers had noted their hardiness under earthbound conditions, observing that although the animals thrive in a damp environment, when conditions go dry, they can shut down for as long as 10 years until the environment moistens up again. Some accounts have compared the water bears to “Sea Monkeys,” the brine shrimp of comics advertisements that come to you dried up in a little packet, only to “miraculously” come to life when you add water.
On a September 2007 European Space Agency mission, scientists decided to test the tardigrades in the most hostile environment available—in space just above planet Earth. They tested two species of water bear, Richtersius coronifer and Milnesium tardigradum, both entering space as dried out versions of their usual selves. The 120 animals from each species were divided into four groups, one that remained on Earth as a control, two that were exposed to the vacuum of space and different combinations of UV rays, and a fourth that experienced only the vacuum of space without the radiation.
Vacuum OK, UV bad
The animals spent 10 days traveling unprotected far above the earth before returning to Earth, where they were hydrated in the lab. Amazingly enough, all three groups of space-traveling tardigrades initially perked right up and lived for a few days. After that, however, only the vacuum-alone group maintained that rate of survival. In the UV-exposed groups, animals that had experienced the vacuum of space and exposure to UV-A and UV-B survived at rates between 10% and 15%. Animals that had been exposed to all three types of UV—A, B, and C—all died.
Nevertheless, the animals that did survive appeared to thrive, reproducing heartily and generally living the usual life of the unusual water bear. Researchers find their ability to withstand radiation particularly intriguing, given that the bombardment would normally shred the DNA of most organisms. Investigators hope to find out more about how the bears resist the perils of space, seeking perhaps to co-opt some of the tardigrade’s techniques to use in protecting astronauts.
Space, schmace. How about 4000 m deep?
Tardigrades didn’t really need to travel into outer space—or really, inner space—to prove their toughness. They are known to live as high as 6000 meters up in the Himalayas and as deep as 4000 meters down in ocean trenches. Water bears have also been found living in apparent ease in hot springs above boiling temperature.