When looking to the stars to see if a species could survive, one of the key components required in order for life to be believed to exist has always been the presence of oxygen. Oxygen is an important component to life, but as it turns out there is a tiny presence even in Earth’s ocean that does not require oxygen in order to survive. And this discovery is changing the way scientists are thinking about what it means to sustain life on another planet.
The species, discovered in the Mediterranean Sea, never integrates oxygen into its body, and is constantly surrounded by sulphides which would be poisonous to most other species. The creatures, according to researchers writing for the periodical biology journal BMC Biology have said that the creatures are alive, metabolically active, and can exist entirely without the assistance of oxygen.
The writers came from all across the world, but included Polytechnic University of Italy’s Roberto Danovaro who first discovered the creatures when looking for organisms in extreme environments. He did find several viruses in the waters, as well as bacterium and Archaea. Though there had been some multicellular creatures in the vicinity, they had been thought to have died and then subsequently washed into the area. And not only were they alive and thriving, but also reproducing as they discovered eggs inside some of the critters. This discovery moves the concept of an alien entity existing outside the understood machinations of Earth’s specific environment from the realm of science fiction to that of scientific discovery.
But without oxygen, how could the creatures’ mitochondria produce energy? Rather than the traditional mitochondria found in other creatures such as humans, the creatures have organelles similar to hydrogenosomes discovered in protozoans. The obvious implications is that life could exist in other areas on Earth once thought to be abiotic, such as hydrothermal vents, but it also raises an interesting question about the survival of simple life both on the surface of and deep within other planets. With the discovery of these creatures, a whole new world -or rather thousands of worlds- open up with the possibility of thriving life despite having vastly different surface systems from Earth. So called extremophiles could exist in oxygen lacking hot areas such as volcanic basins or planets that never developed oxygen.
Such life is suspected to have been around long before the oxygen levels rose and complex organisms started appearing in the fossil record some 500 million years ago. Unfortunately, it is unknown if a more complex organism can evolve from a simple extremophile, or if these creatures are at the end of their evolutionary journey simply due to the fact that their environment doesn’t change in a way that promotes the thriving of genetic aberrations and therefore true evolution. Either way, however, these little creatures do show us a way that life on this planet continues to surprise scientists in how it can thrive in hostile environments and gives those studying exoplanets all the more hope about discovering life out there in the galaxy.