Multi-Cellular Life Thrives in a Permanent No-Oxygen Environment!

In my last post, I talked about the organisms that can, amazingly, thrive without any source of light. The deep sea is the home to hundreds of extremophiles (organisms that flourish in extreme environments) but recently, researches found something that puts even the chemosynthetic life on the hydrothermal vents to shame.

Scientists and researchers previously thought that only single-celled organisms could survive in the anoxic (oxygen deprived) areas of the deep ocean. Even when multi-cellular organisms were found in these areas, they were assumed to have sunk from the oxygen-filled waters of higher ocean zones.
Roberto Danovaro, et al, at BMC Biology discovered the first multi-cellular animals that survive in these zero oxygen environments. These organisms live and reproduce entirely without oxygen. Over the past ten years, Italian and Danish scientists sent multiple expeditions to collect sediment from the hypersaline anoxic basins of the Mediterranean Sea, located almost two miles below the ocean surface. Ecosystems like these are permanently devoid of oxygen and, until recently, have had completely unexplored biodiversity.

Danovaro and his team discovered that the sediments collected from the L’Atalante basin, are inhabited by three distinct multi-cellular species of the phylum Loricifera completely new to science. Although researchers don’t completely understand the biochemistry of these new organisms, they know that these organisms lack mitochondria (the organelle present in most animals cells and is sometimes called the cell’s “powerhouse”). Instead, these organisms seem to have organelles called hydrogenosomes that use anaerobic chemistry and are usually associated with endosymbiotic prokaryotes.

This first evidence of a complete life cycle for a multi-cellular organism in a no oxygen environment is very compelling. It also makes the idea of complex life forms on oxygen-free planets seem much less like a giant leap of faith and more like a distinct possibility.

(For more information and for the original photos see BMC Biology.)