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Scientists Accidentally Discover First-Ever "Animal" That Doesn't Need Oxygen To Live

Scientists Accidentally Discover First-Ever "Animal" That Doesn't Need Oxygen To Live

Scientists have discovered that a jellyfish-like parasite does not have a mitochondrial genome-the first multicellular organism known to have this absence. That means it does not breathe and able to live its entire life without oxygen.

Researchers at the National Academy of Sciences have now identified the first animal that does not use oxygen for breathing: Henneguya Salminicola, an 8-millimeter white parasite relative of jellyfish that infects the flesh of Chinook salmon. The parasite forms small white cysts in the salmon muscle, which the researchers say may not harm the fish—or infect humans.

The research was published in the Proceedings of the National Academy of Sciences.

Multicellular organisms use oxygen to produce energy, a process that occurs in mitochondria. But when scientists searched for them in the parasite, they were completely absent, indicated that the animal did not breathe oxygen. The reason why this animal has lost its genes to breathing is unclear.

Researchers found that the organism lost its mitochondria genome and many of its nuclear genes involved in the transcription and replication of the genome.
The researchers are not yet sure how the organism generates energy. Biologist Dorothee Huchon of Tel Aviv University, Israel "suggested that it might draw energy from its host or engage in a breathing technique that does not involve oxygen, similar to anaerobic non-animal organisms."

The team suspects that this strange trait is the product of Henneguya Salminicola's extreme lifestyle, which may involve alternating between two hosts — fish and worm — both live in sediments with deficient levels of oxygen.

Huchon also added, we don't know why this Henneguya Salminicola has lost this ability while all of its immediate relatives, whom we have identified, are using oxygen. Adaptation to an anaerobic environment is unique to single-celled eukaryotes and has also evolved in a multicellular parasitic animal. Therefore, Henneguya Salminicola provides an opportunity to understand the evolutionary transition from aerobic to an exclusive anaerobic metabolism.

This finding is not just a change in our understanding of how life can work here on Earth, and it could also have ramifications for the search for extraterrestrial life. 

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