The FINANCIAL -- Researchers have discovered the only known animal that does not need oxygen to survive. It's the first multicellular animal found in the wild to not have the DNA. Does this discovery mean that we should rethink the need for oxygen-based metabolisms as a prerequisite for animal life?
Researchers just discovered a unique organism that doesn't need to breathe. Instead, the tiny parasite lives in salmon tissue and evolved so that it doesn't need oxygen to produce energy. Stephen Atkinson, senior research associate at Oregon State University's Department of Microbiology told CNN: "When we think of 'animals,' we picture multicellular creatures that need oxygen to survive, unlike many single-celled organisms including protists and bacteria." "In our work, we have shown that there is at least one multicellular animal that does not have the genetic toolkit to use oxygen," he added. The H. salminicola is a myxozoan cnidarian, a type of animal related to jellyfish and coral. It lives inside salmon and "steals ready-made nutrients" from it, Atkinson said, instead of consuming oxygen directly. Atkinson and his team don't think this species is the last oxygen-free animal, CNN reported.
A tiny parasite called Henneguya salminicola is the first known multicellular animal that can survive without oxygen, according to a study published Tuesday in the journal Proceedings of the National Academy of Sciences by researchers at Tel Aviv University. In fact, it couldn't breathe oxygen even if it wanted to — it gave up the process as it evolved. Researchers made the discovery accidentally while sequencing the "Henneguya" genome. Mitochondria, aka the powerhouses of the cell, capture oxygen to make energy through aerobic respiration — but researchers were surprised to find that H. salminicola lacks mitochondrial genes. However, it is still unknown exactly how exactly the parasite produces energy, according to CBS News.
Until the new discovery, there was debate regarding the possibility that organisms belonging to the animal kingdom could survive in anaerobic environments. 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 Earth when oxygen levels rose. "It's not yet clear to us how the parasite generates energy," Prof. Huchon says. "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 characterizes anaerobic non-animal organisms." According to Prof. Huchon, the discovery bears enormous significance for evolutionary research, is written in Tel Aviv University press release.
It's the first multicellular animal found in the wild to not have the DNA, which contains the genes responsible for respiration, and has lost "the ability to perform aerobic cellular respiration," per the study. Some single-celled organisms do not need respiration to survive. H. salminicola is a fairly common parasite, causing "milky flesh" or "tapioca" disease in salmon, according to a guide published by the Alaska Department of Fish and Game. "Milky flesh" disease results in unsightly cysts on the salmon's flesh but is generally harmless to humans and the fish itself. Because H. salminicola resides inside the fish, the tiny creature has evolved to survive with inadequate oxygen supply. Researchers found that over the course of its evolutionary process, the animal has been able to survive by eliminating so many of the traits associated with multicellular species, USA today reported.
Parasitic species like Henneguya salminicola often lose features because the species they attack provides so much for them. If this organism rarely sees much oxygen, then losing the genes needed to perform oxygen-dependent reactions would be the expected outcome. It's also possible that having a smaller genome and less complicated internal structure would be evolutionarily favorable for these organisms. Does this discovery mean that we should rethink the need for oxygen-based metabolisms as a prerequisite for animal life? Not entirely. It's pretty clear that these organisms would have a hard time surviving without animal hosts to provide many of the things we normally associate with more complicated organisms. So, it's entirely possible that the oxygen-based metabolism enabled by complicated cells remains essential for the origin of animals. It's only after those animals exist that it may be dispensable, Ars Techinca wrote.