Washington: For the first time, scientists
have claimed to have discovered animals that live without
oxygen deep under the Mediterranean Sea.
These creatures called 'loriciferans', which measure less
than one millimetre in length and somewhat resemble jellyfish
sprouting from a conical shell, were found by team of Italian
researchers from 10,000-feet deep hyper-salty basins in the
Though scientist in the past have found a wide variety of
single-celled organisms that live anaerobically, or without
oxygen, they never had an encounter with live multi-cellular
or metazoan animal living without oxygen in deep seas.
According to researchers at the Polytechnic University of
Marche in Ancona, Italy, the new findings could shed light
on what life might have looked like before the rise of oxygen
levels in the deep ocean and the appearance of the first large
animals in the fossil record roughly 550 million to 600
million years ago, LiveScience reported.
The deep Mediterranean basins are completely anoxic, or
oxygen-free, and loaded with toxic levels of sulfides. In
these extremes, the researchers were only expecting to see
viruses, bacteria and other microbes.
Roberto Danovaro, who led the team that conducted three
expeditions off the south coast of Greece looking for signs of
life in samples of mud from deep hyper-salty basins, said they
have earlier found bodies of multi-cellular animals in these
But they "were thought to have sunk there from upper,
oxygenated, waters", said Danovaro.
Instead, "our results indicate that the animals we
recovered were alive," the scientist said, adding that "some,
in fact, also contained eggs".
The scientist explained that electron microscopy revealed
the three new species of loriciferans found from the basins
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."
According to biological oceanographer Lisa Levin of the
Scripps Institution of Oceanography in San Diego, the
implications of this discovery might also reach far beyond the
The new finding "offers the tantalising promise of
metazoan life in other anoxic settings. For example, in the
subsurface ocean beneath hydrothermal vents, or subduction
zones, or in other anoxic basins," Levin said.
Danovaro and his team reported their findings online in
journal BMC Biology.
First Published: Thursday, April 08, 2010, 17:46