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Do All Animals Need Oxygen to Live?

Updated Mar 05, 2024
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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.”

    Frequently Asked Questions

    Do all animals require oxygen to survive?

    While the vast majority of animals do require oxygen for survival, there are exceptional species that can live without it. For instance, certain parasitic lice and some anaerobic microorganisms have evolved to thrive in environments devoid of oxygen, utilizing alternative biochemical processes for energy.

    How do animals that don't need oxygen survive?

    Animals that can survive without oxygen have adapted to use other chemical processes for energy. For example, some species of lice can rely on anaerobic respiration, where they derive energy from compounds other than oxygen, such as nitrates or sulfur. This allows them to inhabit environments that are inhospitable to most other life forms.

    What is the role of oxygen in animal respiration?

    Oxygen plays a critical role in the process of cellular respiration for most animals. It acts as the final electron acceptor in the electron transport chain, enabling the production of ATP, the energy currency of the cell. Without oxygen, this process would halt, leading to a lack of energy for vital biological functions.

    Can any vertebrates live without oxygen?

    Currently, all known vertebrates require oxygen to live. Their complex organ systems, particularly the brain and muscles, demand high levels of oxygen for aerobic respiration. However, some fish, like the goldfish and crucian carp, can survive for extended periods in low-oxygen environments by producing alcohol as a byproduct of anaerobic respiration.

    What environments are home to animals that don't need oxygen?

    Animals that do not require oxygen are often found in extreme environments such as deep-sea vents, hot springs, or the intestinal tracts of other animals. These environments are typically anaerobic (lacking in oxygen) and can be rich in other chemicals that these organisms use for energy.

    How does the absence of oxygen affect an animal's metabolism?

    Animals that live without oxygen have metabolisms that are not based on oxidative phosphorylation, which is the process most animals use to generate ATP with oxygen. Instead, they may rely on fermentation or anaerobic respiration, which are less efficient and result in different byproducts, such as methane or hydrogen sulfide, rather than water and carbon dioxide.

AllThingsNature is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

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