Don’t Breathe: There’s a life form that doesn’t require oxygen

From the realm of the really cool:

Henneguya salminicola is a species related to jellyfish, a multicellular animal that does not need oxygen to live.

H. salminicola is a parasite that lives in fish.  It’s harmless to people, but leaves white spots on the fish it infects.

Animal that doesn’t need oxygen to survive discovered

24 February 2020

by Michael Le Page

Breathing oxygen is seen as a fundamental characteristic of multicellular animals, but we have found at least one that can’t do it.

“It has lost the ability to breathe oxygen,” says Dorothee Huchon at Tel Aviv University in Israel. It remains a mystery how this animal, a parasite that infects salmon, gets the energy it needs without oxygen, she says, but it probably steals it from its host.

All plants and animals were thought to use oxygen to generate a fuel called adenosine triphosphate (ATP), which powers cellular processes. The generation of ATP from oxygen takes places in structures called mitochondria.

Each mitochondrion has its own tiny genome that is separate from the main genome in the cell nucleus. But when Huchon and her colleagues sequenced the DNA of Henneguya salminicola, which is related to jellyfish, they thought they had made a mistake because they found no mitochondrial DNA at all.

Further studies confirmed the finding. When the team stained H. salminicola with a blue fluorescent dye that binds to DNA, no DNA was visible in cells outside the nucleus. By contrast, when they stained a closely related parasite, blue dots corresponding to mitochondrial genomes were visible outside the nucleus.

So while the cells of H. salminicola have structures that look like mitochondria, they can’t make the enzymes needed to use oxygen to produce ATP. “These are not true mitochondria,” says Huchon.


  1. KG says

    There are many, many life forms that don’t breathe oxygen as we do – anaerobic bacteria, which use a variety of chemical reactions in place of the oxygenation of glucose we employ. All will “need oxygen” in the sense that some of the atoms making up their bodies will be oxygen atoms. What’s unusual here is that Henneguya salminicola is a eukaryote – its cells have nuclei and other internal structures like ours – but lacks the key feature of functioning mitochondria.

  2. woodsong says

    There are a few other animal species that don’t need free oxygen out there. I found this in the Wikipedia page on one of the deep-sea hypersaline anoxic basins in the Mediterranean Sea (the L’Atalante basin):

    The dark gray anoxic sediments at the bottom of L’Atalante lake are covered with a 1 cm (0.4 in) loose black layer. Microbes found in the sediments are almost all (90%) various species of Bacillus. In 2010, three metazoan species, all in the Loricifera phylum, were discovered living in the sediment, the first multicellular lifeforms known to live entirely without oxygen.

    I haven’t read more than the Wiki page for Loricifera (LINK), but they look pretty cool. Three species in the phylum have been found in this “brine lake”, and have degenerate mitochondria.

    The page on Loricifera also mentions this about the L’Atalante basin:

    Despite such harsh conditions, this anoxic and sulphidic environment is teeming with microbial life, both chemosynthetic prokaryotes that are primary producers, and a broad diversity of eukaryotic heterotrophs at the next trophic level.

    Emphasis mine. Apparently there are quite a variety of microbes that we’d expect would need oxygen that have adapted to environments without it. Very cool!

    This is the first animal I’ve heard of in an aerobic environment that has lost it’s need for oxygen. That’s different and interesting!

    The sheer variety to be found in living things is truly amazing.

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