Tardigrades - Water bears
Tardigrades are microscopic creatures measuring 0.1mm to 1.2mm long. They look like chubby bears with eight legs but move very slowly – this is where the name Tardigrade comes from, it means ‘Slow walker’
When viewed under the microscope they crawl around in a clumsy manner making them a popular subject to study. They can be found living on land (especially in moss and on beach sediments) as well as in freshwater and in the sea.
Most Tardigrades use a sharp straw-like mouthpiece to feed on plant sap. Some seawater Tardigrades are carnivorous and eat tiny animals such as nematodes and rotifers.
|Tardigrade - water bear © R. Gills and R. J Haro, University Wisconsin|
Water bears sent to space!
Tardigrades are hardy creatures and are able to withstand extreme pressure (6000 atmospheres) and temperatures (-272oC to 151oC). The little creatures were put to the test in September 2007 when Ingermar Jonsson of Sweden’s Kristianstad University and colleagues launched two species of dried-up Tardigrades into space.
After 10 days in space - with no air, intense rays from the sun and no water the Tardigrades were rehydrated and a handful managed to survive! They are the first animals on earth known to be able to survive the harsh conditions of space.
|Scanning electron micrography of an adult Tardigrade © Goldstein Lab|
Coming back to life!
Tardigrades have the ability to perform cryptobiosis – this is when a creature can survive difficult environmental conditions, such as freezing or lack of oxygen for a very long time. Tardigrades can dry out and survive for years without water. When water becomes available they are able to rehydrate and come back to life, all in a matter of minutes!
Travelling on the wind
Dried out Tardigrades (known as a tun) are so small and light, the wind will often pick them up like grains of dust and blow them for thousands of miles.