If the Earth is threatened by an apocalypse like situation courtesy a lot of Hollywood films which always show world being at the edge of destruction, tardigrades will still be alive. These cute microscopic somewhat odd looking animals are among the toughest creatures on Earth. They are known to withstand the shock of boiling water and temperatures that near absolute zero that is – 459.67 degrees Fahrenheit or – 273.15 degrees Celsius. Some of them have survived the crushing pressures of the deep ocean and are also known to go without water for decades. Tardigrades can even survive in the vast vacuum of space. Japanese researchers thawed a group of tardigrades that they found in 2014 after they had been frozen for 30 years, and voila they not only got revived but started reproducing too. We wonder what will it take to actually kill them? Also Read - School Bus-Sized Asteroid to Zoom Past Earth Today, NASA Says There is Nothing to Worry

A group of scientists asked the question that what it would take to end all life on Earth in a new paper in Nature’s Scientific Reports journal. The authors of the paper, physicists from Oxford and Harvard wrote, “Much attention has been given in the literature to the effects of astrophysical events on human and land-based life. However, little has been discussed on the resilience of life itself.” The question was asked in a hypothetical manner and was important because if a mass extinction event occurred it would be nice to know if life could grow afresh, evolve and prosper on Earth. Chinese Scientists Teleported A Particle In Space For The First Time, The Photon Sent Is A Major Breakthrough Also Read - MIT Scientists Discover New Earth-Sized 'Pi Planet' That Orbits its Star in 3.14 Days, Isn't Hospitable

The last known mass extinction of dinosaurs which occurred 66 million years ago was due to an asteroid impact and took out 80% of the other species on the planet. However, some small animals and reptiles survived which evolved into the present animals and humans. According to researchers if the tough tardigrades go extinct, then the Earth would be “sterilized” for life. Tardigrades are indestructible only when they enter a special state called cryptobiosis. Tardigrades, in harsh environments tuck in their legs and expel all moisture from their bodies and go in state called tuns. Also Read - 'Potentially Hazardous' Asteroid Will Zoom Past Earth on September 1, Is It Dangerous? Know Here

In the tuns stage the tardigrades produce glycerol (antifreeze) and secrete trehalose, a kind of simple sugar that has preservation properties. A 2009 paper in Protein Science explains, “Trehalose is viewed as a cocoon that traps the biomolecule inside a glassy matrix, like amber-encasing insects.” The tardigrade achieves a mummified appearance in a glass suit of armor when the trehalose crystallizes and reduces its metabolism by 99.99 % and waits for a more favourable environment. There are different species of tardigrades and all have different adaptations for a wide variety of environmental threats. Gilbert Hill In Andheri Is One of The World’s Only Three Oldest Things Still Battling Time: Pics of 66 Million Years Old Rock will Mesmerize You

The only thing that can wipe out tardigrades from the face of the Earth are deadly radiation from a nearby star that has gone super nova, gamma ray burst from an unknown origin or an asteroid impact. Since the first scenario is almost not feasible as a very high amount of energy that is around 560,000,000,000,000,000,000,000,000 joules of energy will be needed to vaporize the oceans, luckily no nearby star can produce such a high amount of energy. For the second scenario to take place a gamma-ray burst would have to be within a range of 42 light years, once again the chances are very small. The asteroid impact is most feasible but since there are only 19 asteroids which has a mass of 1.7 quintillion kilograms or greater to incinerate the oceans and none of them are on a collision course towards Earth so we can take a sigh of relief that these tardigrades will not be extinct in the near future and hence life will continue as we know it on Earth.