What’s the toughest creature on Earth? Well, it’s definitely not us, even though we talk a big game. I don’t think there’s an objective measurement of toughness, but tardigrades are definitely in the running. They’re also known as water bears, and they’re so small that you need a microscope to see them. They can survive in some of the worst environments on and off the planet: high pressures, low pressures, extreme temperatures, dehydration, lack of food… You can easily find them all around us on Earth, although you might never know it.
Tardigrades have even been sent to space. Curled up into a protective inert form called a tun, two thirds of them survived being exposed to solar radiation and the vaccuum of space. People talk about cockroaches surviving nuclear winter, but to me, it sounds like the tardigrades have them beat in everything but a wrestling match.