Elio Schaechter of Small Things Considered ponders a recent discovery that small multicellular animals, members of the Loricifera and metazoa groups, are able to survive in an anoxic environment known as L’Atalante Basin, a brine “lake” at the bottom of the Mediterranean.
"Life without air—a term coined by Louis Pasteur, the discoverer of anaerobiosis—has been thought to be exclusively a property of microbes, be they prokaryotic or eukaryotic. Multicellular organisms were thought to lack this talent. Until recently that is, when an Italian and Danish group led by Roberto Danovaro looked at an unusual-sounding habitat, a brine “lake” at the bottom of the Mediterranean, nearly 200 km from Crete. Called L’Atalante Basin, this area was formed when salt dissolved from the sea’s subsurface and accumulated in underwater depressions. Eight times more saline than seawater, this layer does not mix with the water column above it and, like the underlying sediment, is completely anoxic. This particular site is not unique; so-called oxygen minimum zones are found in all the oceans at fairly shallow depths as such things go, usually from 200 m to 1,500 m. Characteristically, they have very low available oxygen and lots of sulfide.
Extremophilic archaea and bacteria are common in such inhospitable-sounding environments, and so are a few eukaryotic microbes, notably protozoa. The news is that one can also find small multicellular living animals at this site."
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