The carnivorous water bear, or tardigrade, is a small, multicellular animal that is found all over the world. It can survive extreme conditions like dehydration, radiation, and temperature extremes through cryptobiosis. Water bears prey on organisms like roundworms and rotifers. They reproduce through self-fertilization and lay eggs externally. Water bears have been used to test survivability in space and eliminate roundworms in soil. They can withstand radiation levels over 1000 times what humans can survive.