World’s Toughest Animals.

Who do you think is the toughest animal inhibiting planet earth? Your guess would be some single celled bacteria or a yeast or maybe even human! But you are wrong! Ever heard of animal called tardigrades? And they are also very primitive. Fossils have been found which could be carbon dated to Cambrian period over 500 million years back.

To understand why tardigrades are dubbed as the toughest animal to exist in nature, we need to understand various stressors that effect and destroy our cells. The most important substances for a cell to function normally are DNA molecules, proteins and water.

Different stressors that ruin our cells are:

• Drying cell out.
• Radiation.
• Freezing, this leads to ice formation.
• Extreme pressure which flattens the cells out.

Now let’s have a look at each stressors individually. When a cell dries out its membrane ruptures and leaks, the proteins unfold and they aggregate, making them useless. When we expose the cells to freezing cold the water inside freeze and form ice crystals this destroys the cell membrane. When a cell is exposed to high levels of radiations it destroys the DNA of the cell, without which it won’t have information to perform metabolism. The same is when the cells are heated to temperatures beyond 100 degrees. Extreme pressure, well you know what happens when something is exposed to high pressure! It flattens out.

To tackle cells being dried out and extreme pressures applied tradigrades enter a trance state named TUN. In this it loses its water and shrinks itself to a form a structure that closely resembles a dust musk. In this state it metabolism is .01% of normal activity. Hence it survives extreme pressure, heating and drying the cells out.

The exact mechanisms of the cell being able to survive radiations and high temperatures are still under investigation but it has been speculated that the cells of tradigrades somehow protect their DNA molecules from being damaged and have a mechanism to repair molecules which are. It is also curious to note that these creatures have made a two way trip to outer space and have survived, some even reproduced in the extreme of outer space. In some experimental work they have endured a scorching temperature of 150 degrees.

Tardigrades have been exposed to temperatures closed to absolute zero (-273.16 degrees for strangers to science. All molecular activity ceases at absolute zero.) and they have reanimated when brought in contact with water. Amazing, isn’t it? How do they do it then? Scientists reckons that they survive these conditions by their ability to freeze water outside their cell rather than on the inside.

It wouldn’t do much harm to call the immortals. They truly are nature’s anomaly and a wonder. The toughest creatures.