Salmon parasite is world’s first non-oxygen breathing animal


Scientists have discovered an unusual species of parasite hiding the muscles of salmon. The tiny species, comprised of just ten cells, is unlike all other animals known to science. The species, Henneguya salminicola, doesn’t breathe oxygen.

Over the course of its evolution, the parasite abandoned breathing and consuming oxygen in order to produce more energy.

“Aerobic respiration was thought to be ubiquitous in animals, but now we confirmed that this is not the case,” Dorothee Huchon, professor of zoology at Tel Aviv University, said in a news release. “Our discovery shows that evolution can go in strange directions. Aerobic respiration is a major source of energy, and yet we found an animal that gave up this critical pathway.”

Several fungi species, as well as amoeba or ciliate lineages, have lost the ability to breathe oxygen over long periods of evolution.

When scientists sequenced the genome of the myxozoan species, a relative of jellyfish and corals, they found its mitochondrial genome was missing. The mitochondria is responsible for collecting oxygen and converting it into energy.

Because the parasite is without mitochondria, scientists determined Henneguya salminicola no longer breathes oxygen. The parasite — described this week in the journal PNAS — provides proof that animals can survive anaerobic environments.

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