Cryptobiosis

of study. Tardigrades, also known as water bears or moss piglets, are small animals, about 0.5 mm in length of the phylum Tardigradia. They are well known for their extraordinary ability to survive, and are notable for their capacity to endure even the harsh conditions of outer space (Jönsson et al. 2008). When not active, some species of lichen-and-moss-inhabiting terrestrial tardigrades may exist in states collectively referred to as cryptobiosis. Marine tardigrades have not evolved the capacity to enter these states due to a presumed lack of need to do so in their more stable environments. Cryptobiosis is subdivided into several other states according to what induces it, although they all entail the near stand-still of metabolism as the organism dries up and (usually) becomes a form referred to as a “tun”. These states are anhydrobiosis (induced by dry environment), cryobiosis (cold), osomobiosis (changes in osmolarity), and anoxybiosis (lack of oxygen). Of these, anhydrobiosis, osmobiosis, and cryobiosis are considered “true cryptobiosis”, as they entail formation of a tun. Anhydrobiosis involves a loss of both “free water” within the aqueous solutions in the body, as well as the “bound water”, which maintains the structure of nucleic acids, membrane phospholipids, and proteins, and is believed to be replaced by compounds such as trehalose, and glycerol (Kinchin 1994). Anhydrobiosis may be maintained for up to around a decade and recovered from within a few minutes to…

While in this state, their metabolism lowers and their water content drops. Their ability to remain desiccated for long periods of time is dependent on the levels of “non-reducing sugar trehalose, which protects their membranes.” While in cryptobiosis, tardigrades are known as a tun. They can survive in this state for a very long time only reanimating when they come into contact with…

Generally, when they are in an active state, meaning they crawl, eat, reproduce, etc, they are the toughest animals alive. When exposed to extreme conditions, the Tardigrade exhibit an extreme answer to the stresses called cryptobiosis, or anabiosis. When in this state, their metabolism cannot be detected. They can continue to be exposed to extremely high X-ray radiation, as high as 570,000 rads. They appear unaffected by very high pressures or vacuum. These animals can handle temperatures…