Discovered! First-ever 'animal' that can survive without oxygen
Researchers have discovered the only known "animal" that does not need oxygen to survive, a common parasite that largely preys on salmon.
Scientists have discovered a jellyfish-like parasite that does not need oxygen to produce energy needed for its survival. The finding could help researchers shed light on how alien life could exist on other planets.
The tiny, less than 10-celled parasite Henneguya salminicola lives in salmon muscle, according to the finding published on Tuesday in the journal PNAS.
Researchers at Tel Aviv University in Israel say the jellyfish-like parasite spends its life clinging to the inside of North Pacific salmon in a low to zero-oxygen environment. The organism doesn't have a mitochondrial genome -- a system that breaks down oxygen that multicellular organisms use to power their cells and breathe, the Daily Mail reported citing the study.
According to researchers, they don't know exactly how it survives without oxygen but suggest it could be leeching energy producing chemicals from the salmon. But it is not harmful to the fish and can stay with it for its entire life cycle, say study authors.
"Aerobic respiration was thought to be ubiquitous in animals, but now we confirmed that this is not the case," said Dorothee Huchon, a professor at Tel Aviv University (TAU) in Israel.
"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," Huchon said.
Some other organisms like fungi, amoebas or ciliate lineages in anaerobic environments have lost the ability to breathe over time, the researchers said.
The new study demonstrates that the same can happen to an animal -- possibly because the parasite happens to live in an anaerobic environment, they said. The researchers noted that the parasite's anaerobic nature was an accidental discovery.
Until the new discovery, there was debate regarding the possibility that organisms belonging to the animal kingdom could survive in anaerobic environments, the researchers said.
The assumption that all animals are breathing oxygen was based, among other things, on the fact that animals are multicellular, highly developed organisms, which first appeared on the Earth when oxygen levels rose, they said.
"It's not yet clear to us how the parasite generates energy," Huchon said.
"It may be drawing it from the surrounding fish cells, or it may have a different type of respiration such as oxygen-free breathing, which typically characterises anaerobic non-animal organisms," she said.
According to Huchon, the discovery bears enormous significance for evolutionary research.
"It is generally thought that during evolution, organisms become more and more complex, and that simple single-celled or few-celled organisms are the ancestors of complex organisms," she said.
"But here, right before us, is an animal whose evolutionary process is the opposite. Living in an oxygen-free environment, it has shed unnecessary genes responsible for aerobic respiration and become an even simpler organism,” Huchon added.