Tardigrades, or “water bears,” are small arthropod-like organisms found on every square meter of the Earth’s surface. They can enter a state of suspended animation called cryptobiosis, allowing them to survive extreme conditions such as radiation, high pressure, and extreme temperatures. Tardigrades are a popular research topic for scientists.
Tardigrades (sometimes called “water bears”) are small (0.1 – 1.5 mm), often microscopic arthropod-like organisms that superficially resemble a cross between a bear and an insect. Tardigrades can be found in large numbers on lichens and mosses, although they are found everywhere. A small clump of moss can have a few thousand tardigrades. Scientists often find tardigrades by soaking a piece of moss in fresh water.
Tardigrades are most famous for their extreme hardiness. They are found on virtually every square meter of the earth’s surface, from the seabed, where the ambient pressure is up to 1000 times the surface, to the top of the Himalayan mountains, where there is a third less oxygen than at sea level. Tardigrades have been found under meters-thick layers of ice and in hot springs with a temperature above the boiling point of water.
Tardigrades are among the few animals, including rotifers, nematodes and brine shrimp, that are capable of entering a state of suspended animation known as cryptobiosis, in which metabolism drops to less than 0.01% of normal and blood water can drop to 1% of normal. It is required when environmental conditions become too harsh for normal survival. In this state, the tardigrade ceases all movement and can essentially remain that way indefinitely until environmental conditions improve. Cryptobiosis is made possible by a non-reducing sugar called trehalose, which protects their membranes until they wake up.
Cryptobiotic tardigrades are able to survive extreme pressures, temperatures, radiation, and desiccation. Scientists have shown that tardigrades can survive the vacuum of space, or the pressure of 6,000 atmospheres, six times greater than the pressure at the bottom of the Mariana Trench, the lowest point in the sea. Tardigrades can be heated to 151°C (304°F) for a few minutes, refrigerated to -200°C (-329°F) for days, even survive a cooling to one degree above absolute zero for a few minutes.
Tardigrades can withstand 5,700 grays of radiation, about 500 times more than is fatal to a human. The ability to withstand such radiation is particularly unusual, as there are no natural areas on Earth with such high levels of radiation, so evolution had no particular reason to select animals with such incredible tolerance.
Tardigrades continue to be a popular research topic for scientists studying microscopic animals.
Protect your devices with Threat Protection by NordVPN
