Life is a fundamental component of the Universe. Perhaps that sounds a bit mystical, but what else are we to think when our own home, Earth, offers up such amazing diversity? Scientists have found the first animals that can survive and reproduce entirely without oxygen, deep on the floor of the Mediterranean Sea. The team, led by Roberto Danovaro from Marche Polytechnic University in Ancona, Italy, found three new species from the Loricifera group. He told BBC World Service they were about a millimetre in size and looked like jellyfish in a protective shell. "We plan to go back and see if there are new surprises for us," he added. One of the three new Loriciferans (so-called because of their protective layer, or lorica) has already been officially named Spinoloricus Cinzia, after the professor's wife. The other two, currently designated Rugiloricus and Pliciloricus, have still to be formally described. They were discovered in the course of three oceanographic expeditions conducted over a decade in order to search for living fauna in the sediment of the Mediterranean's L'Atalante basin. The basin, 200km (124m) off the western coast of Crete, is about 3.5km (2.2m) deep and is almost entirely depleted of oxygen, or anoxic. (Jackson) Fifteen years ago, this would have sounded like something out of an X-Files episode. Please Register or Log in to view the hidden image! (Image via BBC) According to BBC's Peter Jackson, the Marche Poly team recovered three separate species of organism, and viable eggs for two of them: Although it was not possible to extract the animals alive in order to show that they could live without oxygen, the team was able to incubate the eggs in anoxic conditions aboard on the ship. The eggs hatched successfully in a completely oxygen-free environment. "It is a real mystery how these creatures are able to live without oxygen because until now we thought only bacteria could do this," said Professor Danovaro, who heads Italy's Association of Limnology (the study of inland waters). "We did not think we could find any animal living there. We are talking about extreme conditions - full of salt, with no oxygen." The discovery of the new Loriciferans represents, he said, a "tremendous adaptation for animals which evolved in oxygenated conditions". Although we might expect certain caveats establishing boundaries to the profundity of the discovery, some scientists are already welcoming, even celebrating the news: Commenting in the journal BMC Biology, Lisa Levin of the Scripps Institution of Oceanography said that before this discovery, "no one had found [animals] capable of living and reproducing entirely in the absence of oxygen". "Loriciferans are rarely reported," she noted. "Whether they were overlooked or are exceedingly rare and thus not sampled is unclear. Perhaps scientists have been looking for them in all the wrong places." (ibid) And, naturally, the implications are vast, including the discussion of extraterrestrial life and, possibly, the origins of life on Earth. But at the very least, we might say, "Hello, Spinoloricus cinzia. It is very nice to meet you." ____________________ Notes: Jackson, Patrick. "First oxygen-free animals found". BBC News Online. April 8, 2010. News.BBC.co.uk. April 8, 2010. http://news.bbc.co.uk/2/hi/science/nature/8609246.stm
Fascinating! Thanks Tiassa. But this puzzled me… Why do we assume that this organism first evolved in oxygenated conditions? The oceans have always been there and, presumably, have always been as deep as they are now and, presumably, have always been anoxic at those great depths. Why couldn’t this organism have evolved with a purely anaerobic respiration?
Because it's an an animal. Loricifera is a phylum within the kingdom Animalia. There are at least six genera and a hundred other species. All other loricifera, and all other animals, breathe oxygen. So it's certain beyond a reasonable doubt that the entire clade evolved from oxygen breathers and that these three species evolved from an ancestor with a successful mutation that replaced mitochondria with another kind of organelle suitable for anaerobic metabolism, the hyrdogenosome. Of course the operative phrase is "beyond a reasonable doubt." It would be remarkable if the first animals had hydrogenosomes, and a clade branched off with a mutation for mitochondria, and that clade went on to populate the whole planet--remarkable but not impossible. The basin in which these animals were found has an exceptionally high salt concentration, which inhibits the water from mixing with the oxygenated waters above. This environment is apparently very rare.
