Cryptobiosis

Often called moss piglets or even pygmy rhinoceroses, tardigrades are cute little invertebrates that are the subject of much research. Closely resembling eight-legged pandas, these microscopic organisms have found their way into many heated discourses and the laboratories of eminent scientists, thanks to their unique life cycle, specifically a stage called cryptobiosis.

It is an ametabolic state, i.e., where metabolism is wholly suspended, and the organism is caught in a state swinging between life and death. Organisms such as the tardigrades show active states of cryptobiosis as a means to battle adverse environmental conditions. The process has often been compared to resurrection from death. It is a reversible process and is brought on by the absence of water and other unfavourable conditions.

This process is characterised by desiccation, wherein all metabolic activities of the organism temporarily come to a stop.

Types of Cryptobiosis

The Different Kinds of Cryptobiosis Commonly Observed are as Follows:

Anhydrobiosis

• The word ‘anhydrobiosis’ means to live without water. 

• Some organisms such as lichens, mosses, algae and yeast show the ability to survive in conditions of extreme water stress. This is aided by desiccation of the organism’s body. 

• The organism in question can lose up to 97% of its water content and shrink into a form called tun that is one-third of its original size. 

• The animal retracts in its head and legs and curls into the tun-shaped form. This helps to minimise the surface area of the body. In this stage, the animal can survive almost any type of hardship.

No wonder it has led to scientists brainstorm over these microbes’ durability and an astonishing capacity to survive in the most extreme of conditions. 

• Anoxybiosis is a state of cryptobiosis when the organism takes in water to preserve it in the absence of oxygen.

•  It goes through a state of complete immobilisation.

Cryobiosis

• Another form of cryptobiosis, in cryobiosis, the organism freezes and suspends its metabolism but can be revived. 

• Temperatures below the cytoplasm’s freezing point can suppress molecular activity and induce the organism to go into this state. 

• The process of cryobiosis is a fascinating one, with the cryobiotic animals releasing several substances called cryoprotectants. These help to slow down the process of tissue freezing and allows the body to transition into cryobiosis smoothly.

The animal undergoing cryobiosis may often take on the shape of an ice-crystal that can be revived by thawing when the situation is favourable.

Did You Know?

In 2007, tardigrades acquired worldwide fame and admiration for being the first multicellular organisms to survive exposure to outer space. These podgy little animals can stand all sorts of solar radiation and heat, even direct exposure to the sun.

Revise What You Learned so far with the Following Quiz.

Pop Quiz 1

1. Anhydrobiosis occurs when organisms suspend metabolic activity in the absence of __________.

1. Oxygen

2. Heat

3. Sunlight

4. Water

Chemobiosis

• The stage of cryobiosis when all metabolic activities are brought to a stop, as a response to very high levels of chemical toxins. 

• Tardigrades are known to show chemobiosis.

Osmobiosis

• Osmobiosis occurs when solutes drastically increase in concentration in the surroundings of the organism. It is thought to be a quick response to high salinity which causes the osmotic swelling of the body, leading it to burst. 

Animals Exhibiting Cryptobiosis

In addition to the super-efficient tardigrades, several other organisms also show cryptobiosis. However, cryptobiosis in humans, as of now is still a field of active research. Notably, scientists have been successful in coming up with a technique known as Emergency Preservation and Resuscitation. The process has been tested on pigs and came out with successful results.

Brine Shrimp

Brine shrimps are small crustaceans that thrive in salty water bodies around the world. They show cryptobiosis by producing structures called dormant eggs to weather unfavourable conditions. These eggs are metabolically inactive and can sustain boiling temperatures, as well as those below freezing point.

Yeast

Dry yeast, commonly used as a baking agent shows cryptobiosis. The yeast encapsulates itself in a thickened, dry coat of dead cells. These can then survive at room temperature or even in freezing conditions.

Pop Quiz 2

1. Which of the following organisms show cryptobiosis?

1. Tardigrades

2. Tiger

3. Dogs

4. None of these

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