First multicellular organism found in oxygen free environment

GLaDOS

http://www.popsci.com/science/article/2010-04/first-ever-multicellular-animals-found-oxygen-free-environment

In the 236 years since oxygen was identified as a life-giving necessity, no scientist anywhere has discovered a multicellular animal capable of living without the stuff. Until now. Researchers from the Polytechnic University of Marche in Ancona, Italy*, have discovered three new species that live their entire life in an anoxic pit beneath the Mediterranean Sea. This discovery drastically revises science's understand of where animals can thrive.
Prior to this discovery, the only organisms capable of life in oxygen-free environments were viruses and bacteria.
Unnamed Loriciferan: via Nature

Unlike plants, all previously discovered animals, and fungi, the newly discovered animal species don't use mitochondria, the cellular organelle that converts sugar and oxygen into water, CO2 and, energy, to power their cells. Instead, these weird creatures have an organelle that resembles a hydrogenosome, a cellular component used by some microbes to produce energy with complex enzymatic reactions. The organisms themselves, none of which have been named yet, all belong to the phylum Loricifera, measure less than 0.04 inches long, and were found almost 10,000 feet down in sediment previous assumed to contain only viruses and bacteria. This is not the first time that scientists have discovered animals living in an anoxic environment, but all the previously discovered species needed to surface periodically for some O2. That makes these creatures the first animals ever discovered that spend their whole lives without oxygen.
How these animals evolved, and what else might be down in this forbidding environment remains to be seen. University of Marche scientists still have a great deal of analysis to do on these animals, but one thing is for sure: our understanding of animal life will never be the same.

Really changes perspectives for evolution, did it develop from oxygen utilising organisms and lose that function, or is there a whole lineage of anaerobic multicellular organisms?


Also interesting in terms of life on other planets.

darjeeling

ScienceNerd wrote: »

http://www.popsci.com/science/article/2010-04/first-ever-multicellular-animals-found-oxygen-free-environment


Really changes perspectives for evolution, did it develop from oxygen utilising organisms and lose that function, or is there a whole lineage of anaerobic multicellular organisms?


Also interesting in terms of life on other planets.

Based on their position in the tree of life (link), we can deduce that the ancestors of these newly-discovered animals once had the ability to use oxygen, and that this has been lost over time.

Loricifera have been grouped into the superphylum Ecdysozoa by comparison of their ribosomal RNA genes with those of the rest of the living world (paper). Other Ecdysozoan animals all possess mitochondria and use oxygen, as do all animals outside this curious little phylum. Even most of the known species of Loricifera use oxygen. The explanation involving fewest evolutionary changes, then, is that the common ancestor of all animals had mitochondria which could metabolise oxygen.