Water is very important to living organisms in that it is an essential part (composes over 90%) of the structure of a living protoplasm. In many processes, water is used both as a metabolite and as a solvent for other substances. Although, water is indispensable, some structures like spores, seeds, cysts, eggs etc. can remain alive for long periods without water.
In these specialized structures which are used mainly for reproduction or perennation, the physiological activities are considerably reduced while the water content is low.