New discovery reveals a parasite that needs no oxygen to live

Science has long thought that multicellular life needed oxygen to survive. It turns out that assumption was wrong as a new DNA information on a parasite has been discovered about a parasite described as jellyfish-like. The parasite lacks the mitochondrial genome and is the first known multicellular organism to lack that genome.

Lacking the mitochondrial genome means that the parasite doesn't breathe and needs no oxygen to survive. Scientists note that not only does the discovery change how life can work on Earth, it also has implications in the search for extraterrestrial life. Scientists say that life started to metabolize oxygen over 1.45 billion years ago.

It started with a larger archaeon engulfing a smaller bacterium, and the new home of the bacterium was beneficial to both. That symbiotic relationship resulted in two organisms evolving together and eventually, the bacterium turned into an organelle called mitochondria. Every cell in a human body, save red blood cells, has mitochondria. There are known organisms that can survive in low-oxygen conditions and some single-cell organisms that have anaerobic metabolism.

The possibility of exclusively anaerobic multicellular organisms has been the subject of debate. The team was studying a common salmon parasite called Henneguya salminicola. It belongs to the same phylum as corals, jellyfish, and anemones. It creates cysts on salmon that aren't harmful and lives with the salmon during its entire lifecycle.

It has been known to survive low oxygen conditions, but how it was able to do that was unknown without looking into its DNA. The dive into its DNA revealed that it has lost its mitochondrial genome. It has also lost the capacity for aerobic respiration, and almost all nuclear genes involved in transcribing and replicating mitochondria. Exactly how the parasite survives is a mystery.