Oxygen-Free Animals Discovered—A First

Deep in the Mediterranean, scientists have discovered the first complex animals known to live without oxygen.

It was previously thought that only viruses and single-celled microbes could survive without oxygen long-term.

But three new species of multicellular animals found during recent research expeditions live comfortably in oxygen-free depths, said team leader Roberto Danovaro of Italy's Polytechnic University of Marche.

"The bodies of multicellular animals have previously been discovered [in oxygen-free zones] but were thought to have sunk there from upper, oxygenated waters," Danovaro said in a statement. "Our results indicate that the animals we recovered were alive. Some, in fact, also contained eggs."

The new animals are microscopic—each measuring less than a millimeter across—and they resemble tiny jellyfish. (Read about giant mucus

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