Try not to breathe

Well, this is intriguing. One of the defining characteristics of a lot of life on Earth is the need for oxygen. Oxygen molecules are a ready source of energy that macroscopic lifeforms like you and I take full advantage of. Mind you we've found all sorts of microorganisms (mostly archaea) which can survive without any oxygen at all. Some live off things like sulfur, while others like to digest methane. For a long time, it was believed that complex animals can't survive without a supply of O₂ to breathe. Until now.

This squiddy looking creature is called loriciferi. It can grow to about a millimetre in size, and it's a newly discovered species. One of three species discovered at the bottom of the Mediterranean in the sediment of the L'Atalante basin, some 200km West of Crete. The basin is around 3.5km deep and almost completely devoid of oxygen.

These new loriciferans are the first complex animals ever found which can live without oxygen. Unfortunately, none of the survived the journey up to the surface, but their eggs did. Not just that, but those eggs successfully incubated and hatched without any oxygen at all. The most remarkable thing about this is that animals have always used oxygen. Some believe that oxygen is what gave life the supply of energy it needed to grow into large complex forms to begin with. The loriciferans, however, have evolved back to a state where they don't need it anymore. And that's pretty incredible. Maybe the so called "dead zones" in the oceans, where oxygen is scarce, might not be quite so dead after all...

The astrobiological implication here is obvious. Complex life doesn't need oxygen to survive. If for whatever reason, the oceans on worlds like Europa turn out to be anoxic, there's still hope that complex life might exist there. And that's really quite inspiring!