Surviving Absolute Zero Temperatures

We humans consider ourselves to be the most dominant species to inhabit Earth and believe we can survive some of the most hostile conditions, but are we the fittest species on Earth? Probably not, writes Nishant Chakravorty. 

There is a group of organisms known as extremophiles that can survive in geographical conditions not favourable to the survival of most species, such as extremes of temperatures, high atmospheric pressure and high levels of radiations—and perhaps the most well-known and complex extremophile is the tardigrade.

Tardigrades survive temperatures ranges between absolute zero (-273.150 C) and boiling point of water (1000 C). They are known to survive extremes of atmospheric pressure and ionising radiations (a part of the electromagnetic spectrum that can cause damage to normal health and well-being of an organism).

Their name means “slow walker” and was coined by the Italian biologist Lazzaro Spallanzani. They are also known as water bears owing to their slow gait. Tardigrades are usually 0.05 – 1.2 mm in length and are found in every nook and corner of the world, which means they are omnipresent.

Extremophiles have gained a lot of attention from researchers and the media owing to their potential to serve as model organisms for space research.

Tardigrades in Space (TARDIS), for example, was the first project planned to evaluate their ability to survive in space. In September 2007 Ingemar Jönsson from the Kristianstad University in Sweden and his team launched tardigrades into the orbit aboard the FOTON-M3 spacecraft for the first time. Tardigrades unshielded from UV were killed by extreme radiations, but others thrived and even laid eggs that managed to hatch.

Extremophiles have become interesting models to test the capabilities of life, teaching us an important Darwinian concept survival of the fittest—and they can be observed in moss or lichen samples after immersing them in water for up to 24 hours. The samples should then be drained off and observed under a microscope. They appear as small barrel-shaped organisms with bilateral symmetry. This experiment can be easily performed in a classroom.