Survival skills
A human being can survive an average of three to five days without the intake of water. The issues presented by the need for water dictate that unnecessary water loss by perspiration be avoided in survival situations. The need for water increases with exercise.
Cryptobiosis
Anhydrobiosis is the most studied form of cryptobiosis and occurs in situations of extreme desiccation. The term "anhydrobiosis" derives from the Greek for "life without water" and is most commonly used for the desiccation tolerance observed in certain invertebrate animals such as bdelloid rotifers, tardigrades, brine shrimp, nematodes, and at least one insect, a species of chironomid ("Polypedilum vanderplanki"). However, other life forms, including the resurrection plant "Craterostigma plantagineum", the majority of plant seeds, and many microorganisms such as bakers' yeast, also exhibit desiccation tolerance. Studies have shown that some anhydrobiotic organisms can survive for decades, even centuries, in the dry state.