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April 13, 2010

A Life Without Air

When you think of an organism, you probably think of some type of animal. These creatures need one particular element to gain energy and survive: oxygen. Most of the sugars and fats that are burned within our bodies, and those materials are made with oxygen. There are some bacteria which can survive anaerobically - without air - but certainly no animals that can, right?

An anaerobic animal,
of the group Loricifera
Image Source: Science Daily
Well... not quite. Deep in the Mediterranean Sea live little multicellular creatures that have never come across oxygen. More than that, they are submersed in sulphides, which are usually toxic to animals. Researchers had previously found some multicellular organisms in this and other deep hypersaline anoxic basics, but had assumed that they had died and floated down into this harsh environment. Not the case with these little Loricifera, however. Tests showed that not only where the animals alive, they were thriving and reproducing.

So, how do they do it? Most animals, including humans, need to metabolize oxygen using mitochondria. This process produces energy. For a short period of time, individual cells can produce enough energy to survive without oxygen, but not for any extended length of time. These creatures live in a complete absence of oxygen. The researches used an electron microscope to see what the Loricifera used to produce energy. Instead of the aerobic mitochondria common in pretty much every other animal, they have hydrogenosomes, similar to those found in bacteria that also inhabit anaerobic environments. In other words, instead of using oxygen dissolved in the water to survive, they use the hydrogen dissolved in the water.

This finding is really exciting. Before this, scientists had guessed that there must have been some form of animal that lived without oxygen, way back in the early history of life (550 to 600 million years ago). This gives us more clues about the nature of these creatures. It also opens the door to more research in other anoxic part of the ocean. It seems unlikely that the Loricifera species is the only animal that thrives in this environment, now that we've discovered it is possible.

Source: Science Daily- First Animals to Live without Oxygen Discovered