Animals not requiring Oxygen

http://www.treehugger.com/files/2010/04/first-oxygen-free-animal-discovered-marine-dead-zone.php

First-Ever Animals Found Living Without Oxygen in Marine Dead Zone
by Brian Merchant, Brooklyn, New York on 04. 8.10
SCIENCE & TECHNOLOGY

Life Will Find a Way . . .

You're likely familiar with the ever-growing marine dead zones, areas in the ocean where no life was believed possible due to depleting oxygen levels. But in a truly startling discovery, scientists have stumbled upon the first animal that can survive without oxygen--a feat that until now was only possible in bacteria. This has a number of implications: both regarding the possibility that life may yet adapt to more severe conditions on earth, and on whether life is possible on other oxygen-free planets--and may be more abundant than we thought.

It looks like a tiny jellyfish in a protective shell. It measures around a single millimeter. And it can survive and reproduce without any oxygen at all. The new species of Loriciferan, named already named Spinoloricus Cinzia after the wife of the scientist who discovered it, and it could be the biggest biological discovery in recent times.

The BBC reports that scientists from the Marche Polytechnic University in Italy found the creature in the Mediterranean Sea's L'Atalante basin--which is "about 3.5km (2.2m) deep and is almost entirely depleted of oxygen, or anoxic." They collected some specimens, which they incubated in an oxygen-free environment--and the eggs hatched successfully in the complete absence of oxygen.



The Oxygen-Free Animal
From the BBC:

"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".
This discovery is especially important when paired with the facts that these marine dead zones are doubling in size around the world every 10 years. This is happening largely because of human activity (of course); it's the result of nitrogen-rich sewage spewing into the coastlines across the globe.

A partial map of marine dead zones--where oxygen-free creatures may yet flourish. Via NASA

Marine Dead Zones
The New York Times has a good explanation of what happens:

Nitrogen from agricultural runoff and sewage stimulates the growth of photosynthetic plankton on the surface of coastal waters. As the organisms decay and sink to the bottom, they are decomposed by microbes that consume large amounts of dissolved oxygen. Most animals that live at the bottom of the coastal ocean cannot survive as oxygen levels drop.
And this is happening all around the world (global warming has been found to play a major role, too). With oxygen-deprived areas expanding, it therefore becomes imperative for sea life to adapt to survive without it--which may be what has happened with this Loriciferan. We'll have to see what details emerge about the creature's life cycle, but needless to say, this could be big. The scientists say that it could additionally help them better understand the possibilities of life existing on other planets with radically different atmospheres. In other words, this probably helps the case that it's out there.