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.

Scientists discover animal that doesn't need oxygen to live
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.

COVID-19 amplified America’s devastating health gap. Can we bridge it?

The COVID-19 pandemic is making health disparities in the United States crystal clear. It is a clarion call for health care systems to double their efforts in vulnerable communities.

Willie Mae Daniels makes melted cheese sandwiches with her granddaughter, Karyah Davis, 6, after being laid off from her job as a food service cashier at the University of Miami on March 17, 2020.

Credit: Joe Raedle/Getty Images
Sponsored by Northwell Health
  • The COVID-19 pandemic has exacerbated America's health disparities, widening the divide between the haves and have nots.
  • Studies show disparities in wealth, race, and online access have disproportionately harmed underserved U.S. communities during the pandemic.
  • To begin curing this social aliment, health systems like Northwell Health are establishing relationships of trust in these communities so that the post-COVID world looks different than the pre-COVID one.
Keep reading Show less

Decades of data suggest parenthood makes people unhappy

Decades of studies have shown parents to be less happy than their childless peers. But are the kids to blame?

(Photo by Alex Hockett / Unsplash)
Sex & Relationships
  • Folk knowledge assumes having children is the key to living a happy, meaningful life; however, empirical evidence suggests nonparents are the more cheery bunch.
  • The difference is most pronounced in countries like the United States. In countries that support pro-family policies, parents can be just as happy as their child-free peers.
  • These findings suggest that we can't rely on folk knowledge to make decisions about parenting, on either the individual or societal levels.
Keep reading Show less

Lonely? Hungry? The same part of the brain worries about both

MRI scans show that hunger and loneliness cause cravings in the same area, which suggests socialization is a need.

Credit: Dương Nhân from Pexels
Mind & Brain
  • A new study demonstrates that our brains crave social interaction with the same areas used to crave food.
  • Hungry test subjects also reported a lack of desire to socialize, proving the existence of "hanger."
  • Other studies have suggested that failure to socialize can lead to stress eating in rodents.
Keep reading Show less

A Chinese plant has evolved to hide from humans

Researchers document the first example of evolutionary changes in a plant in response to humans.

Credit: MEDIAIMAG/Adobe Stock
Surprising Science
  • A plant coveted in China for its medicinal properties has developed camouflage that makes it less likely to be spotted and pulled up from the ground.
  • In areas where the plant isn't often picked, it's bright green. In harvested areas, it's now a gray that blends into its rocky surroundings.
  • Herbalists in China have been picking the Fritillaria dealvayi plant for 2,000 years.
Keep reading Show less
Scroll down to load more…
Quantcast