You must have heard about animals like dogs and monkeys being sent into space, even humans keep visiting space pretty frequently now, but did you know that visiting space comes with a lot of limitations!?
Now whenever any living thing is sent to space, they are either kept within the space shuttle or space station, or if they are actually sent outside, it is only after they wear a space suit, because in actual space, humans and other animals can survive only for a few seconds – because, under extremely low pressure, air trapped in the lungs expands, tearing the tender gas-exchange tissues. Water in the soft tissues of your body vaporizes, causing swelling.
This is true for all animals on earth – except tardigrade! Tardigrades also called ‘water bears’ are micro-animals – very very small, measuring only about an mm when fully grown. They are short andplump, with four pairs of legs, each with four to eight claws. But this description does not do them justice – they are one of the strongest organisms on our planet, and the only ones that we know of today to survive in space. In a study conducted on the European Space Agency’s mission, while orbiting Earth at an altitude of more than 160 miles (258 kilometers), the tardigrades were exposed to the vacuum of space for 10 days. They found that tardigrades survived exposure to space vacuum alone very well, with no significant difference in survival pattern compared to other tardigrades observed in a lab on earth.
Not only this – Tardigrades are found everywhere on earth: from mountain tops to the deep sea andvolcanoes; from hottest desserts to coldest Antarctica. Tardigrades are one of the most resilientknown animals, with individual species able to survive extreme conditions that would be rapidlyfatal to nearly all other known life forms, such as exposure to extreme temperatures, extremepressures (both high and low), air deprivation, radiation, dehydration, and starvation. They are alsofound around you – feeding on mosses, in other environments like dunes, beaches, soil, and marineor freshwater sediments. About 1,200 different species of tardigrades exist today and the lifespan oftardigrades range from 3–4 months for some species, up to 2 years for other species under normalconditions.
But the interesting question is – how do tardigrades do this!? How can they exist in places nobody else can? While there are quite a few organisms which can survive some specific extreme conditions. Pyrococcus furiosus surviving upto 121 degree celsius, Clostridium paradoxum surviving in highly acidic mediums with a pH of -0.6 in volcanic springs, Pyrococcus surviving under a pressure of1100 bar in the Mariana Trench; there have been questions as to how can one single organism – theTardigrade – exist in all of these extreme conditions!?
Tardigrade do so with the help of a process called Anhydrobiosis – Greek word meaning ‘lifewithout water’.
Under unfavorable conditions, they go into a state of suspended animation called the “tun” state—in which their body drys out and appears as a lifeless ball (or tun). In this state, their metabolism may decline to as little as 0.01 percent of its normal rate. It is believed that in the tungstate, tardigrades start synthesizing special molecules, which fill tardigrade cells to replace lost water, in a matrix type environment. This matrix locks up cell components that are sensitive to dryness – like DNA, proteins, etc. This keeps them locked in position and prevents them from unfolding or breaking apart or fusing together – basically, keeps them in place. Once the organism is rehydrated, the matrix dissolves, leaving behind all cellular components intact. This technique makes tardigrades the most resilient organisms of our planet!
The next question that baffles most people is – are tardigrades immortal? Of course, not! We talked about tardigrades achieving a ‘tun’ state that makes them live through almost everything – but if they fail to achieve this state, they act as fragile as any of us, and die quickly. In fact, tardigrades take their own time to achieve a ‘tun’ state after being exposed to the ahostile environment. If you expose them to let’s say icy cold temperatures in a matter of seconds, they fail to achieve the state and die.
Tardigrades have invoked the interest of our scientists since long times – and studies are now going on to identify how they stabilize their sensitive biological molecules and processes – and our aim is to copy the same stabilization technique to improve our life – like developing temperature tolerant crops. If someday we can learn to exist in space as long as they do – there are so many questions about the universe that we will be able to answer. Who knows, it might even help human life survive on other hostile planets!
Where classification and studies are concerned, tardigrades are placed in Kingdom Animalia, in phylum named ‘Tardigrada’. Phylum Tardigrada is comprised of over 1,000 species! If you want to study more about classification and other interesting organisms on our planet, you can go on our app to watch videos for ‘Diversity in Living Organisms’.
While most people already hypothesize that tardigrades are creatures of outer space and landed on earth accidentally, and there are controversies revolving around it, but it might be a good topic to research and dwell upon!