6 December 2012, 09:46

The toughest animal on Earth…and in space!

An animal that can live without water, resist extreme temperatures and strong radiation, and has survived the vacuum of space; that is a basic description of a Tardigrade. More commonly called the ‘water bear’, this tiny creature opens up fascinating new perspectives on the process of dehydration, which could be used to preserve food, but also vaccines and blood.

Discovered two centuries ago, the first to describe the Tardigrade was German zoologist, Johann August Ephraim Goeze, who observed in 1773: “Strange is this little animal, because of its exceptional and strange morphology and because it closely resembles a bear in miniature. That is the reason why I decided to call it little water bear.”The name “Tardigrade” (slow walker, in Italian) was introduced a few years later, by the Italian biologist Lazzaro Spallanzani who described the tortoise-like movement of the animal.

In an interview with ‘The Voice of Russia,’ Doctor Lorena Rebecchi from the Department of Animal Biology at the University of Modena and Reggio Emilia in Italy explained that “tardigrades are very small animals. They measure less than one millimeter. If we consider them from the point of view of their evolution, tardigrades can be associated with insects and crustaceans. They are aquatic animals. They live in marine habitats like lagoons or in terrestrial habitats like soils or mosses.” More than 1000 varieties of tardigrade have been discovered, but the total number of existing species is still unknown.

Doctor Rebecchi continued to explain how tardigrades “are able to desiccate and lose about 97% of their body water. They can stay in such a condition for several years. And then they are able to start living again.” This natural biological mechanism is called “anhydrobiosis” and they can stay in such a state for years at a time.

During these dormancy periods, tardigrades are really resistant and can survive in habitats normally hostile to life. Some can survive temperatures ranging from absolute zero (−459 °F) to 300°F. They can be exposed to 1000 times more radiation than other animals, but also to high pressure.

These extraordinary capabilities have piqued the curiosity of scientists’. To test just how resistant tardigrades are, specialists have taken them into space. Rebecchi explained that tardigrades were twice taken to space, in 2007 and 2009. It was a part of the Mission “Tardigrades in space” launched by the European Space Agency. They remained in orbit for about 12 days. The aim was to observe the mechanisms tardigrades develop to resist pressure and microgravity.

In such conditions, said Doctor Rebecchi, tardigrades developed really fast and their eggs were totally normal. It has also been observed that they were able to develop strong mechanisms against oxidation.

Tardigrades are the first animal known to have survived in space. Nevertheless Rebecchi refused to speculate about tardigrades having come from space, or even from another planet. “That’s science-fiction!” Actually, they probably originated within the sea, where there are many species of tardigrade.

The study of ‘water bears’ continues to advance. Among other things, scientists are interested in the molecules tardigrades use to become dry. A biologist at the University of California, John Crowe, discovered that the survival of organisms, such as tardigrades, depends on a sugar known as trehalose. During dormancy periods, the sugar behaves like water inside the cell and keeps the organism alive. This process could be copied to preserve food, but also vaccines, blood for transfusions and DNA. In fact it would allow their shelf life to be extended which would be a big step forward for global public health.

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