The tardigrade (Hypsibius dujardini), also known as the water bear, is considered the toughest animal in the world. These micro-animals can survive in environments that would kill almost any other creature.
Tardigrades can withstand high doses of radiation, extremely low and high temperatures and pressure and long periods of dehydration. Perhaps the most interesting fact about them is their ability to survive the vacuum and solar radiation of outer space, as confirmed in 2007 by the European Space Agency.
Tardigrades usually live in water or moist environments. They can be found in hot springs, solid ice, ocean sediments, ponds, lakes or soil.