I’m often amazed by how much weirder the real world is than the stuff that comes pouring out of the brains of science fiction writers—although, there’s some pretty weird stuff floating around out there, like the questions: Why haven’t we Earthlings discovered that life exists or has existed other places? Where have all the ETs gone?
Extremophiles—which are creatures that can thrive in extreme environmental conditions most living things would find life-threatening—exist on Earth and give us science-fiction wired enthusiasts hope for the discovery of life on other planets.
The weirdness of these creatures eases the harsh reality that, yikes, Earth may be an anomaly—that we exist in this great vastness all alone and are just an accident created by a bunch of random occurrences in the history of our galaxy.
The argument against the possibility of life on other planets usually boils down to the inhospitable nature of such environments. And yet here on Earth, we have creatures who survive and flourish in just such conditions.
An example of an extremophile is the ocean worm, Nereis sandersi, whose home is located near the ocean-floor hydrothermal vents in the Atlantic. These vents spout superheated water and dense mineral deposits with temperatures ranging from 140° to 867° Fahrenheit and yet the creature prevails. Isn’t this type of adaptation possible on planets with a similar environment such as the hydrothermals on Earth?
The Red Flat Bark Beetle
The red flat bark beetle, Cucujus clavipes, thrives in arctic conditions by producing antifreeze proteins that stop water molecules from grouping together.
The Desert Ants of the Sahara
In contrast, desert ants of the Sahara, Cataglyphis bicolor, clamor to the surface during the hottest part of the day to feed on those insects unable to withstand the heat and to avoid predators restricted by the temperatures that can be as hot as 140°F.
The Himalayan Jumping Spider
Himalayan jumping spiders, Euophrys omnisuperstes, have adapted to high altitudes. They have been found as 22,000 feet. For a great PBS video of the jumping click here.
A newly discovered creature—from the loricifera phylum has been identified as an undescribed species of the genus Spinoloricus. It lives without oxygen or sunlight its entire life and occupies salt-laden waters. This is possible because they don’t depend on mitochondria for energy. Instead, they use hydrogenosomes, which doesn’t need oxygen to create energy. (ProbeNote: Interestingly, it is readily accepted that hydrogenosomes evolved from mitochondria. So is this critter a more evolved species than humans?)
The Toughest Guy On the Block
Many bacterial species are considered extremophiles because of their ability to adapt to extremes in temperatures, pressure, pH, salinity, and other abiotic factors.
The Deinococcus radiodurans bacterium—which The Guinness Book of World Records labeled the world’s toughest bacterium—can survive a 15,000 gray dose of radiation by repairing its damaged DNA in a few hours. Ten grays would kill a human and over 1,000 grays kill a cockroach. D. radiodurans bacterium can survive cold, dehydration, vacuum and acid which places it in the company of the rare polyextremophiles.
(ProbeNote: Polyextremophiles can survive a variety of environmental extremes and are not considered—by some—to be true extremophiles. Wikipedia differentiates in this way: Polyextremophiles are not considered extremophilic because they are not adapted to exploit these conditions. This means that their chances of dying increase the longer they are exposed to the extreme environments, whereas true extremophiles thrive in a physically or geochemically extreme condition that would harm most other organisms.)
The Water Bear
One of the most incredible creatures, and a polyextremophile, is called a water bear or Tardigrade. (ProbeNote: The name “Tardigrade” bears some resemblance to Dr. Who’s Tardis—and in more ways than just the spelling.)
The water bear, aka moss piglets, are like the super-powers of the extremophiles and polyextremophiles. The tiny—less than a millimeter in size—creature receives the tag for being the most tenacious guy on the planet. Its evolutionary development has rendered it capable of elaborate dormancy strategies. They can shut down all but the essential biological processes when conditions are not conducive to supporting life.
- They can withstand temperatures from just above absolute zero to just above the boiling point of water.
- They can tolerate pressures six times greater than those found in the deepest ocean hollows.
- They can defy lethal doses of radiation.
- They can go without food or water for years, some say decades. (ProbeNote: One reference stated ten years and another said over 100 years.)
- They can dry out completely—to 3% or less water—replacing the water in their bodies with a sugar called trehalose. Then with a drop of water they can rehydrate, forage, and reproduce.
- And like Dr. Who’s Tardis, the waterbear has been to space and survived. (ProbeNote: More on this revelation next blog post.)
So with all the remarkable and adaptable creatures that we’ve identified on Earth, why are we not pretty certain life exists or did exist on other planets?
Why all the naysayers?
The expeditions we launch to Mars send back images of the planet, yet their mission is not to look for life or even gather specimens, but to see whether conditions were once favorable for life.
Twin landers—Viking 1 and Viking 2—landed on Mars in 1976. Soil was scooped up and experiments run. In one, a belch of a carbon-containing gas was expelled, which seemed to indicate proof of the possibility of life. But NASA’s declared that this was not evidence of life and that the Martian surface could produce the same effect without the aid of microbes.
In 1996, scientists presented evidence of fossil microbes and biochemicals in a meteorite found in the Antarctic. Its origins seemed to be Mars. Believers were questioned and challenged. Non-believers hung tightly to their arguments that the meteorite did not prove Martian life.
There is hope, however, for alien-life-believers. Several missions are in the planning stages for launches in 2020, which will encompass the retrieval of samples from Mars. NASA, Russia—in collaboration with the European Space Agency—and China are among those involved in plans for such a mission.
Other missions are being discussed in addition to Mars to destinations such as to one of Jupiter’s largest moons, Europa, and Saturn’s sixth largest moon, Enceladus.
Why these two moons?
- Europa has a global ocean buried in its depths similar to our Atlantic’s hydrothermal vents.
- Enceladus shoots out large geysers of ice crystals creating the possibility of a probe fly-by and scoop-up sample mission.
For source click here: http://discovermagazine.com/2014/may/15-why-is-et-mia
Worlds of Possibilities for the Open Minded
With all the possibilities evident on Earth of creatures adapting to the harshest of environmental conditions, surely other life-forms have adapted in much the same way and inhabit worlds in outer space.
Then why all the naysayers?
Maybe, we just haven’t asked the right questions, or been to the right places, or been open-minded enough to allow the possibility.
Or maybe some of us have.
And maybe some of them keep secrets for fear of what the knowledge might unleash.
What is your vote for the existence of life on other planets?
- Don’t think so