Extreme Life On Earth Holds Promise For Extraterrestrial Organisms

photo by Gwendal Uguen via Flickr modified by Curiousmatic 

Organisms living on the fringe of Earth’s hospitable conditions are more common than one might think – and they may just hold promise of extraterrestrial life.

Humans have a very rigid reality of the perfect conditions for life. We need air, water, a moderately temperate climate, a steady flow of food, and Netflix (pretty sure that’s a part of the human condition).

That, however, doesn’t mean such conditions are universally crucial. In fact,  some organisms require none of the above.

These organisms are what scientists have dubbed “extremophiles” – organisms capable of thriving in conditions which – to the human body – are utterly inhospitable.

Extremophile – “an organism that is tolerant to environmental extremes and that has evolved to grow optimally under one or more extreme conditions.” Encyclopedia Britannica

Below are some of the world’s most formidable extremophiles, and the fringe conditions in which they live.

Tardigrade – polyextremophile

photo from Wikimedia Commons by Bob Goldstein and Vicky Madden

The tardigrade (named for the french word Tardigrada meaning “slow stepper”), A.K.A. the water bear, though small, is arguably one of the toughest living organisms known to humankind.

They are never over 1.5mm long and boast a laundry list of extreme characteristics, such as the ability to survive in temperatures near absolute zero, in extreme pressures, and without sunlight.

More notably, tardigrades have even been found to live for periods of up to eight years (some accounts tell of 120 plus years) without any water whatsoever.

By contracting their arms and legs and entering a state very close to death, they are able to reduce their metabolism to .01 percent of the normal rate, and subsist until they come in contact with water.

These formidable creatures have been found all over the world; from Antarctica to the Himalayas, and have even endured trips into space.

Deinococcus radiodurans – polyextremophile

photo by Michael Daly via Wikimedia Commons

This bacterium’s ability to withstand extreme doses of radiation earned it a spot as the “world’s toughest bacteria” – no seriously, look it up in Guinness.

Deinococcus radiodurans has been known to survive in ionizing radiation more than 1,500 times stronger than the fatal dose comparable to the human body, and have been discovered living in toxic conditions like those experienced in Fukushima and Chernobyl.

The bacterium’s resistance to radiation has even come in handy for “bioremediation” – specifically, cleaning up mercury residue found in nuclear waste.

Strain 121 – hyperthermophile

photo of Strain 121 via MicrobeWiki

This organism – classified as Archaea, meaning ancient – is a 3.5 billion year old single celled organism much like a bacteria. Aside from being extremely ancient, it has one exceptional characteristic: it’s ability to withstand heat.

Strain 121 is capable of enduring temperatures of up to 235 degrees Fahrenheit (above the boiling point of water), and has been discovered living next to thermal vents in the ocean floor where from which superheated water spews.

Its characteristics make it capable of living in volcanoes, hot springs, and other extremely hot environments.

The takeaway

Extremophiles make science fun. They challenge the notion of what conditions humans consider to be essential and show us that the world is more genetically diverse than we could possibly imagine – even on a microscopic level.

The real appeal of extremophiles, however, comes from their promise for life beyond Earth. If organisms on our planet are capable of thriving beneath ice sheets, inside volcanoes, and in conditions previously thought to be barren of life, they could just as easily do so on other planets.

In the spirit of all that is science-fiction: the truth is out there – and the truth may be in extremophiles.

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James Pero