Animals Living Without Oxygen Discovered for First Time

http://news.yahoo.com/s/livescience/20100408/sc_livescience/animalslivingwithoutoxygendiscoveredforfirsttime

Charles Q. Choi
LiveScience Contributor
livescience.com – Thu Apr 8, 8:30 am ET

A wide variety of single-celled organisms that live anaerobically, or without oxygen, had been found in the past, usually deep underwater or deep underground. But researchers had not found a multi-cellular or metazoan animal that did so until now - the giant tube worms that live by hydrothermal vents, for instance, rely on dissolved oxygen.

In the past decade or so, researcher Roberto Danovaro at the Polytechnic University of Marche in Ancona, Italy, and his colleagues conducted three expeditions off the south coast of Greece looking for signs of life in samples of mud from deep, hyper-salty basins in the Mediterranean Sea more than 10,000 feet (3,250 meters) deep. These basins are completely anoxic, or oxygen-free, and loaded with toxic levels of sulfides.

In these extremes, the investigators were only expecting to see viruses, bacteria and other microbes. The bodies of multi-cellular animals had previously been discovered in these sediments, "but were thought to have sunk there from upper, oxygenated, waters," explained Danovaro.


Instead, "our results indicate that the animals we recovered were alive," Danovaro said. "Some, in fact, also contained eggs."

These creatures, which measure less than 1 millimeter long, are known as loriciferans. They somewhat resemble jellyfish sprouting from a conical shell.

Electron microscopy revealed the three new species of loriciferans the researchers discovered lack mitochondria, the energy-making organelles or components in our cells that allow us to generate energy from oxygen among other functions. Instead, they possess large numbers of organelles resembling hydrogenosomes - anaerobic forms of mitochondria - that were previously seen in single-celled organisms inhabiting no-oxygen environments.

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