Anhydrobiosis is a particular state a living organism may enter into, used as a form of resistance. The organism is extremely dehydrated and vital functions are completely or almost completely suspended. A return of humid conditions causes the organism to trigger its (revivability) metabolism.
The seeds of flowering plants are the most common form of anhydrobiosis. Some animals are also capable of anhydrobiosis, especially nematodes (small roundworms living in the soil), rotifers (small fresh water marine animals) insects and crustaceans (artemis living in very salty areas and even in salt works). The most amazing case is that of the tardigrade, a small animal similar to an arthropod that can withstand
- temperatures near absolute zero and a maximum temperature of 151°C,
- very long freezing periods (tardigrades collected in glacial (core) samples that have remained there for 2000 years returned to life),
- a pressure of 600 megapascals (the pressure that would be present at the bottom of a hypothetical ocean 60,000 metres deep),
- exposure to X-rays of 570,000 rads (500 rads is the lethal dose for humans) during anhydrobiosis.
According to Russian zoologists, tardigrades survived an trip into space.