The discovery of the Henneguya salminicola parasite in 2020 has biologists worldwide scratching their heads. This blip of an organism, composed of fewer than 10 cells, doesn’t need oxygen to live. And since it doesn’t rely on aerobic respiration to create energy, it doesn’t need a mitochondrial genome or any respiratory genes, either.
Unique as H. salminicola appears to be, the researchers don’t think this is the only oxygen-free animal out there.
- “We have shown that there is at least one multicellular animal that does not have the genetic toolkit to use oxygen,” says Oregon State University research associate Stephen Atkinson, part of the research team working at Tel Aviv University.
- H. salminicola is a myxozoan cnidarian, an animal related to jellyfish and coral. It lives inside salmon and "steals ready-made nutrients" from the fish flesh, instead of consuming oxygen directly, Atkinson said.
- The findings, he added, expand the definition of what an "animal" can be. Atkinson expects that future research will probably find a new spectrum of animals with ”even weirder modes of existence.”