Scientists discover animal that doesn't need oxygen to live

It's the first time scientists have discovered an animal that doesn't perform aerobic respiration.

STEPHEN D. ATKINSON
  • The animal is a tiny parasite called Henneguya salminicola.
  • The parasite infects salmon and lives within the fish muscle, though scientists aren't quite sure how it breaks down nutrients for survival.
  • The findings are published in the journal PNAS.


In the time it takes you to read this article, you're likely to breathe a few dozen times. Some animals don't breathe as often, and they don't require nearly as much oxygen. The Loggerhead sea turtle, for example, can take one breath and stay underwater for about 10 hours. Still, it's long been thought that all animals need to breathe oxygen to stay alive.

But then scientists discovered Henneguya salminicola, an 8-millimeter parasite that doesn't need oxygen to live, and cannot process it as other animals do. The findings are published in a paper in the journal PNAS.

All other animals have mitochondria, which are organelles that act as the "powerhouse" of the cell by breaking down nutrients and converting them into energy. One way mitochondria do this is by converting oxygen into a fuel called adenosine triphosphate (ATP), which drives processes like muscle contraction, nerve impulse propagation, and chemical synthesis. This conversion process is called aerobic respiration.

H. salminicola inside of a salmon

Michal Maňas

But H. salminicola — a cnidarian animal related to jellyfish and coral — don't have mitochondria, and therefore can't perform aerobic respiration. Lead study author Dorothée Huchon discovered this as she was sequencing mitochondria across Myxozoa (a class of parasites).

"My goal was to assemble mitochondrial genome to study its evolution in Myxozoa and... Oops, I found one without a genome," she told Vice. "I first thought that the lack of mitochondrial genome among the DNA sequence was the result of a bug in genome analyses. But then I realized that it has lost not just the mitochondrial genome but the whole set of protein genes that interact with the mitochondrial genome and all the majority of genes involved in respiration."

An evolutionary advantage

Losing that mitochondrial genome appears to have been a less-is-more type of advantage for the parasite.

"Myxozoans have gone through outstanding morphological and genomic simplifications during their adaptation to parasitism from a free-living cnidarian ancestor," the authors wrote. "As a highly diverse group with >2,400 species, which inhabit marine, freshwater, and even terrestrial environments, evolutionary loss and simplification has clearly been a successful strategy for Myxozoa, which shows that less is more."

The researchers aren't quite sure how H. salminicola breaks down nutrients without oxygen. One possibility is that it absorbs molecules from its host. It's hard to tell, however, because the researchers analyzed dead parasites — they'd need to look at parasites living within the fish to get a better understanding of how the creatures operate.

The discovery highlights how much scientists still have to learn about the diversity of life on Earth. Atkinson told CNN that he expects H. salminicola isn't the only animal that can survive without oxygen, or in even "weirder modes of existence."

The search for alien life

One interesting implication of the discovery is what it means for the search for alien life. It's long been thought that, if aliens exist, they'd likely breathe oxygen. After all, it's the best element that we know of for producing large amounts of energy for metabolism, allowing us to "grow large, run and jump and think," as David Catling, a planetary scientist at the University of Washington, told Forbes.

"Because of oxygen's chemical advantages and the history of complex life on earth is so intertwined with oxygen levels," he said. "I think E.T. would also breathe oxygen."

This is one reason why many think Earth-like exoplanets with atmospheres that likely contain oxygen would be good candidates for harboring alien life. But, in a small way, the newly discovered parasite gives reason to think that the search for alien life — and their life-supporting planets — might be far more complicated.

The world and workforce need wisdom. Why don’t universities teach it?

Universities claim to prepare students for the world. How many actually do it?

Photo: Take A Pix Media / Getty Images
Sponsored by Charles Koch Foundation
  • Many university mission statements do not live up to their promise, writes Ben Nelson, founder of Minerva, a university designed to develop intellect over content memorization.
  • The core competencies that students need for success—critical thinking, communication, problem solving, and cross-cultural understanding, for example—should be intentionally taught, not left to chance.
  • These competencies can be summed up with one word: wisdom. True wisdom is the ability to apply one's knowledge appropriately when faced with novel situations.
Keep reading Show less

What the world will look like in the year 250,002,018

This is what the world will look like, 250 million years from now

On Pangaea Proxima, Lagos will be north of New York, and Cape Town close to Mexico City
Surprising Science

To us humans, the shape and location of oceans and continents seems fixed. But that's only because our lives are so short.

Keep reading Show less

Six-month-olds recognize (and like) when they’re being imitated

A new study may help us better understand how children build social cognition through caregiver interaction.

Personal Growth
  • Scientists speculate imitation helps develop social cognition in babies.
  • A new study out of Lund University shows that six-month-olds look and smile more at imitating adults.
  • Researchers hope the data will spur future studies to discover what role caregiver imitation plays in social cognition development.
  • Keep reading Show less

    New study connects cardiovascular exercise with improved memory

    Researchers at UT Southwestern noted a 47 percent increase in blood flow to regions associated with memory.

    An elderly man runs during his morning exercises at the promenade on the Bund along the Huangpu Rive the Bund in Shanghai on May 18, 2017.

    Photo: Johannes Eisele/AFP via Getty Images
    Surprising Science
    • Researchers at UT Southwestern observed a stark improvement in memory after cardiovascular exercise.
    • The year-long study included 30 seniors who all had some form of memory impairment.
    • The group of seniors that only stretched for a year did not fair as well in memory tests.
    Keep reading Show less
    Scroll down to load more…