Anhydrobiosis is a strategy used by some organisms to survive extreme dry spells. During anhydrobiosis their cells come to contain only minimal amounts of water, and no metabolic activity is performed.

A variety of organisms can become anhydrobiotic, including bacteria, yeast, fungi, plants, insects, the tardigrades (see cryptobiosis), mycophagous (fungi-eating) nematodes, and the brine shrimp Artemia salina (also known as "Sea Monkeys" when marketed to children). During the drying out process (desiccation), less available water forces substances to increase in their concentration. Such increases lead to stressful responses within a cell that are similar to those a cell experiences when exposed to high salt environments.