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Cryptobiosis is a state of inactive metabolic activity entered by some lower organisms during an adverse environmental condition. Due to this, activities such as reproduction, repair, and development in an organism stop. Until the environmental conditions become favorable again, the organism can go on living indefinitely in an ametabolic state. After cryptobiosis, it returns to its original metabolic state.
Adverse environmental conditions involve desiccation, freezing, high pressure, high temperature, radiation, and oxygen deficiency. Of these, cryptobiotic desiccation is the most common. Cryptobiosis is often compared to the resurrection from death. It feels like the organism is caught in a state between life and death. It is a reversible process, and organisms return to normal life when the environmental conditions improve and their metabolic state is then restored to its original form.
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Types of Cryptobiosis
There are mainly 5 different types of cryptobiosis:
Anhydrobiosis
Anhydrobiosis is the condition of life without water. It is used to describe a situation where organisms can survive extreme water stress. This state is induced by desiccation. In this state, the organism can lose 97% of its water and shrink to one-third of its size. It changes into a tun-shaped form that reduces the surface area of the body and lets it survive the adverse environment.
Some organisms in which this state is observed are yeast, algae, mosses, lichen, cyanobacteria, etc.
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Anoxybiosis
Anoxybiosis is the state of life without oxygen. In this state, the organism takes in water and immobilizes itself.
Anoxybiosis
Chemobiosis
This state is observed in response to high levels of metabolic toxins. So, as a result, metabolic activities are rendered inactive. This behaviour is seen in tardigrades.
Cryobiosis
Cryobiosis is a state that occurs when the temperature is so low that the water surrounding an organism freeze. When the temperature falls below the cytoplasm’s freezing point, molecular activity is suppressed. That is when this type of cryptobiosis occurs and all metabolic activities are stopped. Often, the organism in such a state assumes the shape of an ice crystal.
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Osmobiosis
Osmobiosis is a condition that occurs when the proportion of solute in a solution that the organism is surviving in increases. Not much is known about this type of cryptobiosis.
Osmobiosis
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Animals Exhibiting Cryptobiosis
There are several species of animals that undergo cryptobiosis. Some of them are:
Brine Shrimp
Brine shrimp are crustaceans that are found in salty lakes. During unfavorable conditions, they produce cysts, which are known as dormant eggs. These eggs are metabolically inactive and can survive dry and anaerobic conditions.
Tardigrades
Tardigrades are microscopic organisms that are found in water. They are eight-legged invertebrates who are likely to survive an apocalypse. A matured tardigrade can undergo cryptobiosis for almost 10 years. Due to this nature of being able to pause their metabolic activities, they can survive extreme conditions of desiccation, temperature, pressure, and radiation.
Tardigrades
Bacteria
During adverse environmental conditions, the bacteria form dormant, tough, non-reproductive structures known as endospores. These help bacteria survive such times as they are resistant to chemical disinfectants, starvation, radiation, temperature and dry environments.
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Yeast
Dry yeast is often used in baking. Live yeast is put in a dry, thick jacket of dead cells along with a growth medium. Yeast can be stored at room temperature, in a refrigerator, or even in a freezer for a long time.
Cryptobiosis in Humans
Humans do not show any signs of cryptobiosis, but research shows it might soon be possible. Researchers are working on ways to save human lives through cryptobiosis. A technique called Emergency Preservation and Resuscitation has been devised and successfully tested on pigs. With this technique, they replace the blood with cold saline fluid, which reduces the body temperature by 10°. Due to this, the body requires less oxygen and, hence it reduces the chance of brain damage. This process gives the doctors a lot more time to cure severe injuries caused by gunshots and accidents. After that, the fluid is replaced with blood and the body warms up gradually.
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Things To Remember
- Cryptobiosis is a state where all metabolic activities in an organism are stopped due to unfavorable environmental conditions.
- There are different forms of cryptobiosis, such as anhydrobiosis, anoxybiosis, chemobiosis, cryobiosis, and osmobiosis.
- Some animals that exhibit cryptobiosis are yeast, bacteria, tardigrades, brine shrimp, etc.
- Humans do not exhibit cryptobiosis, but researchers are working on a technique called Emergency Preservation and Resuscitation to make it happen.
Sample Questions
Ques: Explain cryptobiosis in Tardigrades. (3 marks)
Ans: Cryptobiosis is a condition when organisms halt their metabolic activities to survive unfavourable environmental conditions. Tardigrams exhibit cryptobiosis. They are microscopic organisms that survive in water. These organisms can stay in an ametabolic state for almost ten years. And once in contact with water again, they can go back to their original metabolic states within a few hours. They can survive extreme environmental conditions of desiccation, radiation, temperature, and pressure.
Ques: Explain the terms: Chemobiosis and Osmobiosis (3 marks)
Ans: Chemobiosis - Chemobiosis is a cryptobiotic state observed by some organisms in response to high levels of metabolic toxins. Metabolic activities are paused during this state.
Osmobiosis - Osmobiosis is a cryptobiotic state which occurs in an organism when the proportion of solute in the solution they are surviving in increases.
Ques: Do humans exhibit cryptobiosis? (4 marks)
Ans: Humans do not exhibit cryptobiosis, but scientists are carrying out research to make it possible. They have devised a technique called Emergency Preservation and Resuscitation that has been successfully tested on pigs. In this technique, the blood is replaced with cold saline fluid, which decreases the body temperature by 10°. This, in turn, reduces the oxygen requirement of the body and provides doctors more time to cure severe injuries. After this process, the fluid is replaced with blood and the body warms up, eventually.
Ques: What is anhydrobiosis? (4 marks)
Ans: Anhydrobiosis is a cryptobiotic state observed in animals when there is a lack of water in the environment. It is referred to as a state of life without water. This state is caused by desiccation, where the organism pauses all metabolic activities to survive this adverse condition. During this process, the organism loses up to 97% of its water and shrinks to one-third of its original size. It changes into a tun-shaped form, which reduces its surface area and helps it survive easily. Some organisms that exhibit anhydrobiosis are algae, yeast, cyanobacteria, lichen, mosses, etc.
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Ques: Which of the following can undergo all five types of cryptobiosis? (2 marks)
- Brine shrimp
- Yeast
- Algae
- Tardigrade
Ans: D. Tardigrade
A tardigrade is an animal that can undergo all five types of cryptobiosis. It can survive extreme weather conditions of desiccation, temperature, pressure, and radiation. It is also the only animal that can survive in space. They are capable of spending many years in a cryptobiotic state.
Ques: Is anoxybiosis considered a type of cryptobiosis? (2 marks)
Ans: Anoxybiosis is a cryptobiotic state wherein an animal survives an environmental condition without oxygen by entering an ametabolic state. In such a situation, the organism takes in water and becomes turgid and immobile. But the study of survival rates in this state have shown some conflicting results, and so some do not consider it to be a cryptobiotic state.
Ques: What is cryptobiosis? (4 marks)
Ans: Cryptobiosis is a condition wherein an organism enters an ametabolic state to survive unfavorable environmental conditions. These unfavorable environmental conditions can include desiccation, freezing, high temperatures, high pressure, and radiation. Once the environment is favorable again, they can go back to their original state and restore all metabolic activities.
There are different types of cryptobiosis that include anhydrobiosis, cryobiosis, osmobiosis, anoxybiosis, and chemobiosis. Some organisms that are known to exhibit cryptobiosis are lichen, tardigrades, yeast, brine shrimp, bacteria, etc.
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