Cold is essentially another form of desiccation, so the membrane
protectants of trehalose and glycerol can also act as freeze protectants.
Anoxybiosis caused by rapid decline in oxygen concentration
results in extended, turgid, and immobile animals
that can survive from a few hours to five days depending on
species. Slower lowering of oxygen concentrations allows some
animals to form cysts, which can survive for over a year but are
less resistant to other environmental extremes (for example,
high temperatures). Osmobiosis is experienced by tardigrades in
intertidal and euyhaline environments. However, most limnoterrestrial
tardigrades form tuns in saline conditions.