A tiny parasite called Henneguya salminicola is the first known multicellular animal that can survive without oxygen. Scientists have just discovered that a jellyfish-like parasite doesn’t have a mitochondrial genome – the first multicellular organism known to have this absence. That means it doesn’t breathe; in fact, it lives its life completely free of oxygen dependency. This discovery isn’t just changing our understanding of how life can work here on Earth – it could also have implications for the search for extraterrestrial life. We know there are adaptations that allow some organisms to thrive in low-oxygen, or hypoxic, conditions. Some single-celled organisms have evolved mitochondria-related organelles for anaerobic metabolism, but the possibility of exclusively anaerobic multicellular organisms has been the subject of some scientific debate. That is until a team of researchers led by Dayana Yahalomi of Tel Aviv University in Israel decided to take another look at a commo...