Cryptobiosis or anabiosis is a metabolic state of life entered by an organism in response to adverse environmental conditions such as desiccation, freezing, and oxygen deficiency. In the cryptobiotic state, all measurable metabolic processes stop, preventing reproduction, development, and repair. When environmental conditions return to being hospitable, the organism will return to its metabolic state of life as it was before cryptobiosis.
Types of Cryptobiosis
- Anhydrobiosis: It means “life without water”. It refers to the ability of some organisms to survive extreme water stress. This has been observed in lichens, cyanobacteria, yeast, mosses, algae, etc. This state is induced by desiccation.
- Anoxybiosis: This situation occurs during lack of oxygen when the organism becomes turgid by taking in water and immobilizes.
- Chemobiosis: It is the suspension of metabolic activities in response to high levels of metabolic toxins. Tardigrades exhibit chemobiosis.
- Cryobiosis: It occurs during reduced temperatures. When the water surrounding the organism freezes, cryobiosis is initiated and all the metabolic activities of the organisms are paused.
- Osmobiosis: It occurs in response to increased solute concentration of the solution in which the organism lives. However, less is known about this type.
Animals Exhibiting Cryptobiosis
- Brine shrimp: These are crustaceans that are found in salty lakes all over the world. They produce cysts known as “dormant eggs”, during unfavorable conditions. The cyst is metabolically inactive and can survive in dry and anaerobic conditions. These can survive boiling temperatures and temperatures below the freezing point.
- Yeast: The active dry yeast is commonly used in baking as a leaving agent. The live yeast is encapsulated in a thick, dry jacket of dead cells with some growth medium. Yeast can be stored at room temperature, or in the refrigerator or freezer for a very long time.
- Tardigrades: These are microscopic organisms found in water. A matured tardigrade is 0.5 mm long with eight legs. They have the ability to suspend their metabolism and undergo cryptobiosis for almost 10 years. Due to this nature, they can survive extreme temperatures, pressure, desiccation, and radiation.
- Bacteria: During environmental stress, the bacterial form dormant, tough, non-reproductive structures known as endospores. They help the bacteria to survive when the conditions are not favorable for survival. They are resistant to radiation, drying, temperature, chemical disinfectants, and starvation.
Cryptobiosis in Humans
In humans, it is known as suspended animation. Researchers have devised ways to save lives through cryptobiosis. The doctors in the US have been working on a technique known as emergency Preservation and Resuscitation. In this, the blood in the body is replaced with cold saline fluid, which would decrease the body temperature to 10°C. This chills the body and the brain and there is very less requirement of oxygen by the body. This reduces the chances of brain damage. By doing this they can get ample time to cure severe injuries such as those caused by accidents and gunshots. Soon after the treatment, the saline is replaced with blood and the body rewarms gradually. The process has successfully been experimented on a pig.