Water bears conquer space
October 24th 2008 17:23
There are creatures indigenous to this planet called tardigrades and they are in the news because it has just been discovered that they can live in space. Outer space. Vacuum territory. The place where, it has previously been believed, the only things that can survive are some of the hardier forms of cosmic dust.
Tardigrades are more commonly known as water bears. They are, on average, about the size which requires a microscope to see. But this is not recommended for the squeamish or weak of heart because tardigrades are seriously scary looking critters. Seen under a microscope, they look like a cross between a louse and an angry armadillo with acne.
Their bodies are short and plump and contain four pairs of limbs. Each limb terminates in four to eight claws or discs. They wander about in a slow bear-like gait over sand grains or pieces of plant material.
Water bears already had minor celebrity status because they have shown they can live in some of Earth's most inhospitable places: at the bottom of the ocean, at the top of mountains, and in temperatures ranging from minus 272C to plus 51C. They are resistant to radiation and, bizarrely, to drying out - they can be brought back to life after years of dryness.
But space was a new frontier even for the hardy tardigrades.
They were taken into space aboard the FOTON-M3, a European Space Agency craft launched in September, by scientists who exposed dried-up water bears to open space conditions - vacuum, ultra-violet radiation from the sun and cosmic radiation. Back home, with a drop of water, most of them revived.
Some survived exposure to solar ultra-violet radiation more than 1,000 times higher than ultra-violet radiation on the Earth's surface. Some, scientists said, were able to reproduce after their space trip.
The scientists reported on the venture in this month's edition of the US journal Current Biology.
"How these animals were capable of reviving their body after receiving a dose of UV radiation ... under space vacuum conditions remains a mystery," the report said. "It is conceivable that the same cellular adaptations that let them survive drying out might also account for their overall hardiness."
There are about 600 species of tardigrades on Earth. They were first described by Johann August Ephraim Goeze in 1773, and he gave them the name "little water bear". The name Tardigrada, which means "slow walker", was coined in 1777.
They have been found in the Himalayas above 6,000 metres, in the ocean below 4,000 metres, from the polar regions to the equator, on beaches, in soil and in marine or freshwater sediment. Mostly, though, they like to hang out on the nearest cosy lichen or moss.
Or in space.
theregister.co.uk, www.ieu.edu, wikipedia.org. Image: www.core-orsten-research.de
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