Tardigrades are phylum of aquatic, microscopic animals with segmented bodies and eight legs. Because they live in the water and walk much like bears, they are more commonly known as water bears. However, as boring as they may seem, they are anything but that. Water bears are practically invincible and indestructible.
Water bears are fairly unique among animals because they can survive in extreme environments. They can survive in water chilled to absolute zero, and they can survive in water far above boiling point. They can survive at extremely low pressures such as the vacuum of space and extremely high pressures well beyond the water pressure in the deepest ocean trenches.
Yet, even without water (and food), they can survive in up to 10 years, and even in the waterless vacuum of space, they can survive for, at least, 10 days.
In fact, when encountered with extreme conditions, they actually dehydrate themselves, reducing their bodies water content to less than 3%. This allows them to reduce damage to their bodies and enter a period of suspended animation.
But, if that wasn’t enough, radiation also has little effect on them.
They can withstand 1,000 times more radiation than any other animal. So, after a nuclear war like the one seen in the Fallout video game series, while everything else might be dead or dying, water bears will be just as numerous as they were before. Thus, if you were tasked with slaying a water bear, you’d have a pretty hard job!
Check out this water bear that looks like a real-life bear scratching its back: