Short Wave - Untangling The Science of Octopus Arms

Episode Date: September 19, 2025

Octopuses and their arms are a bit of a mystery.  Not because scientists don’t know how they work; they’re boneless hydrostats, made up of groups of muscles working together and capable of bending, twisting, elongating or shortening — like a frog’s tongue, or an elephant’s trunk. But because scientists are still figuring out how most octopuses use those arms in the wild. Scientists at the Marine Biological Laboratory in Woods Hole and the marine lab at Florida Atlantic University wanted to answer that question. By analyzing videos taken in the wild, they found that octopuses seemed to prefer doing certain tasks with certain arms… and that the majority of the time, they used their front arms to explore and their back arms to get around. Researchers on the project hope that furthering our understanding of octopus behavior and movement will be useful for developing things like soft robotics.Interested in more science discoveries? Email us your question at [e-mail] to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hey, ShoreWivers, Regina Barbara here. And Rachel Carlson with our biweekly Science News Roundup featuring the hosts of all things considered. And today we have the always fun, Ari Shapiro. We're going to miss you, Ari. Oh, I'm only always fun when I'm with you. It's a testament to your show. I love doing it.

So I hear today you're going to tell me about some mysterious red dots in space. Yeah, and how the brain might fill in missing information. And lastly, you'll love this, Ari, the wiggly world of octopus arms. Eight times the fun. Exactly. All that on this episode of Shortwave, the science podcast from NPR. Okay, to kick us off, tell me about these red dots in space. I'm imagining like intergalactic acne.

What is it? Well, let's start at the beginning, Ari. The universe probably started with the Big Bang. At the very beginning. Very, very beginning. So, Ari, this story starts with images from the new James Webb Space Telescope of the very, very early universe. We're talking like 500 million years after the Big Bang, which since the universe is 13.8 billion years old, that's basically less than 5% of the universe's life. So when scientists were looking far back into the dawn of the universe, they noticed these very strange red objects in these images of space.

They debated whether the dots were big black holes or galaxies. But the weird thing was, if they were galaxies, they were much older than they should have been. It will be like checking on your little kid and finding a fully ground adult. That's Bing Jay Wang, an astrophysicist who is part of a team that published a study about one of these red dots in the journal Astronomy and Astrophysics last week. What does her team think these red dots are? So long story short, Ari, we still don't know. They're all very different. They all have like different features.

The lead author of that study astrophysicist Ana de Groff says that our existing models really just don't explain what's going on in this specific case. So any normal star or galaxy model or a black hole model does not fit the data, essentially. So they needed a new model to explain this specific red dots features. And the study's claiming this new model points to a new kind of black hole. One surrounded by a dense cloud of cooler gas, kind of like an atmosphere, but it's not a planet or a star. I didn't know black holes could have an atmosphere. What does that mean exactly? It means that this could be a stage in black hole growth that scientists have never. seen before. It could also be a new clue as to how supermassive black holes at the centers of

almost all galaxies are made. But astrophysicists aren't really sure. Do they have ideas about how that might work? Yeah. So I reached out to astrophysicist at Yale Priya Natarajan, and she says this could be one example of how black holes rapidly grew into supermassive black holes, but that this is only one example of a model that she and her colleague Tala Alexander actually proposed a while ago. They thought that black holes created soon after the Big Bang, with big clouds of dust and gas around them, could rapidly grow to become super massive black holes. So she thinks more work needs to be done. Okay, let's pivot from black holes to holes in information in the human brain. What's the second story? So the brain is wired to fill in visual gaps. For example, Ari, maybe an animal sees the tail of a lion hiding behind a bush, but their brain alerts them as if they've seen the entire lion. So like the brain fills in the gaps to say run. Exactly. And in that case, that brain features really helpful. But sometimes in the case of things like optical illusions, the brain perceives objects that aren't actually there. And because of that, scientists can study illusions to try to understand how the brain fills in those gaps.

A new study in nature, neuroscience did exactly this in mice. So, Ari, I want you to look at an example of what the researcher showed the mice. It's called the Kinesa illusion. And tell me what you see. It looks like three black Pac-Man's. Yeah. Heading for a threesome towards each other. Okay.

Honestly, I like that description. A lot of people see a triangle when they look at it. Oh, okay, yeah, because like the gaps between the pack people's mouths makes a triangle. Yeah, got it. Yeah, exactly. So to a lot of people, it seems like there's a white triangle on top of those black Pac-Men circle things. So this is an example of how the brain fills in the edges of a shape, even when those edges don't exist. And when researchers at the University of California, Berkeley and the Allen Institute in Seattle showed this image to mice, they found a special group of neurons in mice brains specifically involved in that process of filling in the missing edges.

And researchers have known that the brain has neurons that respond to both the edges of real objects and the edges of illusions or objects that aren't really there like that triangle. But these were different neurons, specifically activated by the edges of the illusion. So what can researchers do with that information now that they've identified? this specific brain circuit. One of the study authors, Hayung Shin, says with a lot more work and, of course, work on humans, this could help researchers understand mental disorders that affect perception. The most famous example of that is schizophrenia, but also autism, ADHD, Alzheimer's, many other diseases. Although one limitation of the study is that it's mice.

A mouse can't say whether they see the triangle or not. So there's lots more to be done before we can make claims about humans. Okay, third story, octopus arms. Take it away. Okay, Ari. So this new study came out in the journal's Scientific Reports, and it's all about how octopuses use different arms for different tasks. Scientists analyzed a bunch of videos of octopuses in the wild, and they were like, great, what's each individual arm doing here? Octopuses have eight arms. And to look at what each arm is doing at a specific point,

you have to watch that video eight times. That's Chelsea Benis. She's a field biologist at Florida Atlantic University. University and a co-author of the study. Sounds like a lot of octopus content to go through. What did they find? Two things. One, there was no arm specialization, meaning all of their arms were capable of doing all the same actions.

But two, the octopuses still seem to prefer doing certain tasks with certain arms. The majority of the time they use their front arms for exploration and their back arms for locomotion. Just to be clear, octopus researchers have observed some of these arm preferences in lab settings before. But Kurt Onthank, an octopus researcher at Walla Walla University in Washington State, who's not affiliated with this research, says it's important for us to observe it in the wild too. They're really good at hiding. Just finding them is difficult. And then once you do find them, it's really hard to then ensure that you, the big hairless monkey covered neoprene, is not like messing up their behavior. Huh. Okay. Well, what do we get out of knowing that an octopus might use one arm to give a thumbs up and another to give a peace sign? Yeah. When we asked Chelsea, she told us that it could help us get inspiration for flexible or soft robotics, which she says could be helpful for things like search and recovery or even ocean exploration. And Ari, if you want to see some of the videos the researchers looked at, plus peek at some cute octopuses, we'll have that video online and in our show notes.

They're not octopi? I think it's both right. I think it's both. Anyway, regardless, I look forward to watching. Ari, you are such a great science nerd, and you are always welcome on our show. We're going to miss you. We'll miss you. We love having you on for now. I love nerding out with you. Thank you for enlightening me every week.

You can hear more of Ari on Consider This and P.R.'s afternoon podcast about what the news means for you. This episode was produced by Hannah Chen and Jordan Marie Smith. It was edited by Burley McCoy and Patrick Jaron Watanan. Tyler Jones checked the facts. Tiffany Vera Castro and Patrick Murray were the audio engineers. I'm Rachel Carlson. And I'm Regina Barber. Thank you for listening to Shorewave, the science podcast from NPR.