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Transcript of Tardigrades
Tardigrades, also known as water bears, are microscopic, aquatic organisms which live almost anywhere on Earth. Some species live in moss, lichen, leaf litter, and soil, while others live in fresh or salt water. Tardigrades are nearly translucent and are usually about half a millimeter in length. They have the ability to survive in the harshest of conditions.
Where Can Tardigrades Survive?
Tardigrades can survive in:
Tardigrades in Space
In the year 2007, tardigrades became the first animals to survive in space. The water bear survived sub-zero temperatures, solar winds, and the oxygen-deprived vacuum of space.
There is still much that is unknown about tardigrades. For example, why would water bears need to survive in extreme radiation if they live in moss? Some scientists believe that tardigrades came to Earth from another solar system by hitching rides on meteors! The ability of tardigrades to withstand strong radiation suggests an amazing DNA repair system. Perhaps in the future, this can be used to save the lives of humans who have come in contact with dangerous amounts of radiation.
By Vikram Srinath
Lack of Water
The Vacuum of Outer Space
Tardigrades can survive being heated to 151 °C for a few minutes, or being cooled to -200 °C for days. A few can even last for a few minutes in -272 °C, which is one degree above absolute zero.
Tardigrades can withstand the extremely low pressure of a vacuum, as well as very high pressures, more than 1,000 times atmospheric pressure, which is the pressure exerted by the weight of the atmosphere. Some species of water bear can withstand 6,000 times atmospheric pressure, which is about six times the pressure of water in the deepest ocean trench, the Mariana trench.
Tardigrades can handle 1,000 times more radiation than most other animals. While a human would die of 5 to 10 Gy (a measure of radiation) of gamma rays, tardigrades can survive 5,000 Gy. One factor that may cause this is their ability to effectively repair damage to their DNA resulting from exposure.
Lack of Water
Tardigrades can survive without water for 10 years. When water bears are exposed to frigid temperatures, their body goes from 85% water to only 3%. When tardigrades are in an extremely dry state, they go into a state called cryptobiosis. When the surroundings around the tardigrade dry up, it does too. The creature shrivels up to one-third of its normal size, and is called a tun. As a tun, the water bear can survive just about anything. When rehydrated, they return to their normal state.