Once a week.
Subscribe to our weekly newsletter.
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.
- 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
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.
These alien-like creatures are virtually invisible in the deep sea.
- A team of marine biologists used nets to catch 16 species of deep-sea fish that have evolved the ability to be virtually invisible to prey and predators.
- "Ultra-black" skin seems to be an evolutionary adaptation that helps fish camouflage themselves in the deep sea, which is illuminated by bioluminescent organisms.
- There are likely more, and potentially much darker, ultra-black fish lurking deep in the ocean.
The Pacific blackdragon
Credit: Karen Osborn/Smithsonian<p>When researchers first saw the deep-sea species, it wasn't immediately obvious that their skin was ultra-black. Then, marine biologist Karen Osborn, a co-author on the new paper, noticed something strange about the photos she took of the fish.</p><p style="margin-left: 20px;">"I had tried to take pictures of deep-sea fish before and got nothing but these really horrible pictures, where you can't see any detail," Osborn told <em><a href="https://www.wired.com/story/meet-the-ultra-black-vantafish/" target="_blank">Wired</a></em>. "How is it that I can shine two strobe lights at them and all that light just disappears?"</p><p>After examining samples of fish skin under the microscope, the researchers discovered that the fish skin contains a layer of organelles called melanosomes, which contain melanin, the same pigment that gives color to human skin and hair. This layer of melanosomes absorbs most of the light that hits them.</p>
A crested bigscale
Credit: Karen Osborn/Smithsonian<p style="margin-left: 20px;">"But what isn't absorbed side-scatters into the layer, and it's absorbed by the neighboring pigments that are all packed right up close to it," Osborn told <em>Wired</em>. "And so what they've done is create this super-efficient, very-little-material system where they can basically build a light trap with just the pigment particles and nothing else."</p><p>The result? Strange and terrifying deep-sea species, like the crested bigscale, fangtooth, and Pacific blackdragon, all of which appear in the deep sea as barely more than faint silhouettes.</p>
David Csepp, NMFS/AKFSC/ABL<p>But interestingly, this unique disappearing trick wasn't passed on to these species by a common ancestor. Rather, they each developed it independently. As such, the different species use their ultra-blackness for different purposes. For example, the threadfin dragonfish only has ultra-black skin during its adolescent years, when it's rather defenseless, as <em>Wired</em> <a href="https://www.wired.com/story/meet-the-ultra-black-vantafish/" target="_blank">notes</a>.</p><p>Other fish—like the <a href="http://onebugaday.blogspot.com/2016/06/a-new-anglerfish-oneirodes-amaokai.html" target="_blank">oneirodes species</a>, which use bioluminescent lures to bait prey—probably evolved ultra-black skin to avoid reflecting the light their own bodies produce. Meanwhile, species like <em>C. acclinidens</em> only have ultra-black skin around their gut, possibly to hide light of bioluminescent fish they've eaten.</p><p>Given that these newly described species are just ones that this team found off the coast of California, there are likely many more, and possibly much darker, ultra-black fish swimming in the deep ocean. </p>
Using machine-learning technology, the genealogy company My Heritage enables users to animate static images of their relatives.
- Deep Nostalgia uses machine learning to animate static images.
- The AI can animate images by "looking" at a single facial image, and the animations include movements such as blinking, smiling and head tilting.
- As deepfake technology becomes increasingly sophisticated, some are concerned about how bad actors might abuse the technology to manipulate the pubic.
My Heritage/Deep Nostalgia<p>But that's not to say the animations are perfect. As with most deep-fake technology, there's still an uncanny air to the images, with some of the facial movements appearing slightly unnatural. What's more, Deep Nostalgia is only able to create deepfakes of one person's face from the neck up, so you couldn't use it to animate group photos, or photos of people doing any sort of physical activity.</p>
My Heritage/Deep Nostalgia<p>But for a free deep-fake service, Deep Nostalgia is pretty impressive, especially considering you can use it to create deepfakes of <em>any </em>face, human or not. </p>
How long should one wait until an idea like string theory, seductive as it may be, is deemed unrealistic?
- How far should we defend an idea in the face of contrarian evidence?
- Who decides when it's time to abandon an idea and deem it wrong?
- Science carries within it its seeds from ancient Greece, including certain prejudices of how reality should or shouldn't be.
Plato used the allegory of the cave to explain that what humans see and experience is not the true reality.
Credit: Gothika via Wikimedia Commons CC 4.0<p>When scientists and mathematicians use the term <em>Platonic worldview</em>, that's what they mean in general: The unbound capacity of reason to unlock the secrets of creation, one by one. Einstein, for one, was a believer, preaching the fundamental reasonableness of nature; no weird unexplainable stuff, like a god that plays dice—his tongue-in-cheek critique of the belief that the unpredictability of the quantum world was truly fundamental to nature and not just a shortcoming of our current understanding. Despite his strong belief in such underlying order, Einstein recognized the imperfection of human knowledge: "What I see of Nature is a magnificent structure that we can comprehend only very imperfectly, and that must fill a thinking person with a feeling of humility." (Quoted by Dukas and Hoffmann in <em>Albert Einstein, The Human Side: Glimpses from His Archives</em> (1979), 39.)</p> <p>Einstein embodies the tension between these two clashing worldviews, a tension that is still very much with us today: On the one hand, the Platonic ideology that the fundamental stuff of reality is logical and understandable to the human mind, and, on the other, the acknowledgment that our reasoning has limitations, that our tools have limitations and thus that to reach some sort of final or complete understanding of the material world is nothing but an impossible, <a href="https://www.amazon.com/dp/B01K2JTGIA?tag=bigthink00-20&linkCode=ogi&th=1&psc=1" target="_blank" rel="noopener noreferrer">semi-religious dream</a>.</p>