Metazoan extremophiles

Deep under the Mediterranean Sea, small animals have been discovered that live their entire lives without oxygen and surrounded by ‘poisonous’ sulphides.

Also, from the same article:

“These extreme environments,” said Danovaro, “have been thought to be exclusively inhabited by viruses, Bacteria and Archaea. The bodies of multicellular animals have previously been discovered, but were thought to have sunk there from upper, oxygenated, waters. Our results indicate that the animals we recovered were alive. Some, in fact, also contained eggs.”

So contrary to conventional biological wisdom, metazoan life can thrive in extreme environments.  This new research also helps us appreciate how another popular belief is also probably false….

and that is the belief that Archaea represent the most “primitive” domain of life.   The logic is that since Archaea are largely restricted to existence in extreme environments, this is a relic that reflects their evolution on an ancient Earth, which would certainly qualify as an extreme environment.  In other words, “extreme” becomes associated with “ancient” and “primitive” ( in fact, ‘archaea’ means ‘ancient.’).

But over the years, mundane research has shown the ability of archaeal cells to survive in extreme environments is mostly a derived, rather than primitive, state.  And that’s just not as exciting as thinking that Archaea give us a glimpse into primitive life.  Now that we know metazoans, a clearly derived state, can exist in extreme environments, perhaps the popular notion of life in extreme environments representing a primitive condition can be more widely dispelled.

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