Practice question

Cryptobiosis denotes reversible ametabolic dormant state where measurable metabolism becomes undetectably low, enabling survival of desiccation, freezing, anoxia, osmotic stress, vacuum and radiation. Tardigrades exemplify anhydrobiosis forming tun by retracting legs and head, expelling over 95% body water, replacing with protective trehalose and tardigrade-specific intrinsically disordered proteins that vitrify cytoplasm into glass. Metabolism falls to 0.01% normal, allowing survival decades even in space vacuum. Upon rehydration efficient DNA repair restores activity. While rotifers, nematodes and brine shrimp also show cryptobiosis, tardigrades represent premier model for astrobiology and stress tolerance research globally in laboratories.