TARDIGRADE or Hypsibius dujardin Also commonly known as the ‘water bear’.
IT CAN SMELL YOU AND SEE YOU WITH ITS SINGLE ORIFICE. But not really.
“Tardigrades are well known to many microscopists but few people are aware of their fascinating biology. Characterised by their short bodies (typically 0.5mm long) with eight legs terminating in claws, they were for many years classified with the spiders and mites before it was recognised that their unique biology merited their own phylum, Tardigrada. They are widely distributed from the tropics to the polar regions and occur in a wide variety of habitats including mosses, lichen, soils, sands, leaf litter, marine sediments and for some marine species, in association with marine molluscs. Many of the terrestrial species are able to withstand long periods of desiccation by a process known as anhydrobiosis (“life without water”). The tardigrade forms a dried, resistant state called a tun and can survive for many years without water. When rain arrives, the tun rehydrates and the tardigrade is active again within a few hours. It has been known for tardigrades to survive for over 100 years in this dehydrated form. In addition to resistance to drying, the tun state can also be frozen in the laboratory to -2700 C without killing the animal. This ability is of great survival importance to the tardigrade in times of drought and for some species regular cycles of drying and wetting may help prevent fungal infection of the tardigrade.
In many ways, tardigrades are an ideal subject for the amateur microscopist to study; they are very widespread and can be collected from the nearest garden, roof or gutter, only simple equipment is needed to extract them from their habitat and mounts can be made easily. There are probably fewer than 50 people world-wide working on tardigrades so there is good scope for the amateur to make a real contribution to our knowledge of these creatures. In order to start looking at tardigrades, simply collect some moss from a pavement or roof (the flat Bryum or Ceratodon species are ideal), soak it in tap water for several hours and then squeeze the water out into a transparent dish. Tardigrades can be found at low magnification (a stereomicroscope magnifying x20 is ideal) and can be recognised by their slug-like appearance and active legs. It is from their characteristic bear-like gait that they are given their common name, Water Bears. Examine specimens in a drop of water under a coverslip at x100 to x400, or make permanent mounts for future identification using a water based mountant such as NBS Aqueous Mountant.
For further information on tardigrades, refer to The Biology of Tardigrades by Ian Kinchin (1994, Portland Press). A copy is available for loan to members in the Quekett Lending Library. The Club journal also has several papers published in the last 10 years on tardigrades.”-taken from http://www.nhm.ac.uk/hosted_sites/quekett/tardi.htm
A year ago, 3,000 of them were dried out and fired into space to see if they could handle the cosmic rays, a near vacuum and freezing cold.
Amazingly, after ten days, some of them did. They became the first animals to survive exposure in space without protection.
The experiment, supported by the European Space Agency, was headed by Dr Ingemar Jonsson, of the University of Kristianstad, Sweden.
‘Our principal finding is that the space vacuum, which entails extreme dehydration, and cosmic radiation were not a problem for water bears,’ he said. But admitted that exactly how they survived ‘remains a mystery.’
The water bears were kept in a chamber on board the FOTON-M3 spacecraft as it orbited 270km above the Earth 270km.
A slide was opened to expose them to the vacuum and the cold. Some were also subjected to the Sun’s UV rays which are 1,000 times stronger in space than on Earth and, incredibly, survived for the return trip. They continued to breed successfully.
Dr Jonsson and his colleagues in Stockholm, Stuttgart, and Cologne published the results of the space study in the journal Current Biology.
He said, ‘The ultraviolet radiation in space is harmful to water bears, although a few individuals can survive even that.’
He believes that even if they suffered DNA damage, the little water bears could somehow repair it. The next challenge is to try to understand the creatures’ ‘exceptional tolerance’ to extreme conditions, he said. It could help scientists learn how to treat cancer.
‘All knowledge involving the repair of genetic damage is central to the field of medicine,’ Dr Jonsson said.
‘One problem with radiation therapy in treating cancer today is that healthy cells are also harmed. If we can document and show that there are special molecules involved in DNA repair in multicellular animals like tardigrades, we might be able to further the development of radiation therapy,’ he added.
German scientist Dr Ralph Schill, who also worked on the project, said, ‘I hoped they would make it but I could hardly have expected this result - you can’t simulate some of the space conditions in the lab’.
Water bears exist in nearly all ecosystems of the world. What makes them unique is that they can survive repeated dehydration and can lose nearly all the water they have in their bodies.
When dehydrated, they enter into a dormant state in which the body contracts and metabolism ceases. In this death-like dormant state, water bears manage to maintain the structures in their cells until water is available to ‘reactivate’ them.
In 1998, Japanese scientists subjected the creatures to pressures up to 6,000 greater than our atmosphere. They lived. In tests, they have also survived X-rays and being frozen to just above absolute zero - that’s minus 273.15C, the coldest temperature possible.
‘No animal has survived open space before,’ says developmental biologist Bob Goldstein of the University of North Carolina.
‘The finding that animals survived rehydration after days in open space - and then produced viable embryos as well - is really remarkable.’”-taken from http://www.dailymail.co.uk/sciencetech/article-1054351/Tiny-water-bears-creatures-survive-space.html
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