Tardigrades, or water bears, are an obscure group of invertibrates located between the nematodes (roundworms) and the arthropods (crustacea, insects, and ticks). They live underwater and shrivel into a cask stage when out of water, surviving in a state called cryptobiosis. These microscopic invertibrates feed on the fluid of plant and animal cells. They grow to a size of about 1 mm and can be seen with a microscope. They can live in extreme environments, from hot springs to solid ice.
They can also survive in outer space. It has been nearly a year since the ecologist Ingemar Jönsson, a researcher at Kristianstad University in Sweden, had some 3,000 microscopic water bears sent up on a twelve-day space trip. The aim of the research project, which was supported by the European Space Agency, was to find out more about the basic physiology of tardigrades by seeing if they can survive in a space environment.
"Our principal finding is that the space vacuum, which entails extreme dehydration, and cosmic radiation were not a problem for water bears. On the other hand, the ultraviolet radiation in space is harmful to water bears, although a few individual can even survive that," says Ingemar Jönsson.
This would make them the first animals on earth to survive exposure to the vacuum and radiation of space.