Recent studies done by Somme in 1995 and 1996 have helped to develop a greater understanding of the mechanism tardigrades use to survive extreme temperatures. However, certain animals that live in such environments are able to remain viable in the frozen state. Osmobiosis is a form of cryptobiosis initiated by a decreased water potential due to increased solute concentration in the surrounding solution. Upon immersion in non-ambient saline solutions tardigrades commonly contract rapidly into a tun. However, this is not necessary since active animals can survive high salinity.
Viability decreases with prolonged exposure.
Some tardigrades are found in the marine intertidal zone and can tolerate changes in the salinity of the water. The process by which osmobiosis occurs is not understood but does appear to involve the cessation of metabolism. A reduction of oxygen tension initiates a suspended state in tardigrades, but is not really considered a form of cryptobiosis. Animals in this state remain extended, turgid, and immobile. Tardigrades are very sensitive to changes in oxygen tension and prolonged reduction of oxygen leads to osmoregulatory failure.