Animal That Survives In Space

 

The only animal known to survive the extreme environment of outer space without the help of special equipment turns out to have the most foreign DNA of any species.

Also known as tardigrades, water bears are segmented, eight-legged micro-organisms that are just a fraction of an inch long. Though tiny, these small creatures are best known for their resiliency, which researchers now suspect comes as a result of their strange genome.

They live everywhere, from the tallest mountains to the deepest oceans, and from hot springs to Antarctic ice. They can even tolerate New York. They cope with these inhospitable environments by transforming into a nigh-indestructible state. Their adorable shuffling gaits cease. Their eight legs curl inwards. Their rotund bodies shrivel up, expelling almost all of their water and becoming a dried barrel called a “tun.” Their metabolism dwindles to near-nothingness—they are practically dead. And in skirting the edge of death, they become incredibly hard to kill.

“We had no idea that an animal genome could be composed of so much foreign DNA,” said Bob Goldstein, a faculty member in the biology department of UNC’s College of Arts and Sciences, in a statement. “We knew many animals acquire foreign genes, but we had no idea that it happens to this degree.”

The discovery, published in the Proceeding of the National Academy of Sciences, adds to the evidence that tiny water bears are incredibly unique and seemingly indestructible animals. In 2007, some were even rocketed into space on the outside of a satellite.

When the satellite returned, many of the water bears were still alive. What’s more, some of the females had laid eggs in space, with the young hatching healthily, as though nothing had happened.

In the tun state, tardigrades don't need food or water. They can shrug off temperatures close to absolute zero and as high as 151 degrees Celsius. They can withstand the intense pressures of the deep ocean, doses of radiation that would kill other animals, and baths of toxic solvents. And they are, to date, the only animals that have been exposed to the naked vacuum of space and lived to tell the tale—or, at least, lay viable eggs. (Their only weakness, as a researcher once told me, is “vulnerability to mechanical damage;” in other words, you can squish ‘em.)

Water bears are segmented, eight-legged micro-animals that measure just a miniscule fraction of an inch long. Goldstein, lead author Thomas Boothby and their team determined that water bears acquire 6,000 foreign genes primarily from bacteria, but also from plants, fungi and various single-celled microorganisms.

 The creatures acquire the DNA through a process called horizontal gene transfer. In it, DNA is swapped between species instead of being inherited. While not seen in every organism, the process is changing the way scientists think about evolution as well as the inheritance of genetic material. This is because genetic material no longer has to travel in one direction. Rather, it can be passed sideways along a family tree, not just from one generation to another.

“Animals that can survive extreme stresses may be particularly prone to acquiring foreign genes and bacterial genes might be better able to withstand stresses than animal ones.”