Think oxygen is a requirement for multicellular life? Think again. As ScienceNow reports, a team of Danish and Italian researchers have discovered the first anaerobic multicellular organisms in the depths of the Mediterranean Sea. The organisms, dubbed Loricifera, live in a basin made up of salt brine "so dense that it doesn't mix with the oxygen-containing waters above."
ScienceNow's story includes more juicy details:
The researchers also found examples of individuals that contained eggs and evidence of apparent molting, which led them to conclude that the animals spend their whole lives in the harsh sediments. The creature's cells apparently lack mitochondria, the organelles that use oxygen to power a cell. Instead they are rich in what seem to be hydrogenosomes, organelles that can do a similar job in anaerobic (or oxygen free) environments.
If you can grasp talk of prokaryotes, protozoa, eukaryotes, and metazoans, the full study (including images) is available in PDF format through this page on the BMC Biology website.