Untangling The Science of Octopus Arms

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 https://www.mbl.edu/research/research-centers/eugene-bell-center/bell-center-faculty-and-staff/hanlon-lab and the marine lab at Florida Atlantic University https://biology.fau.edu/marine-lab/people/chelsea-beninice.php 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 [email protected] mailto:[email protected]. Listen 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 http://plus.npr.org/shortwave. See pcm.adswizz.com https://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 https://www.npr.org/about-npr/179878450/privacy-policy

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• 0:00Speaker 00

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• 0:23Regina Barber?

  Hey, Short Whavers. Regina Barber here.

• 0:24Speaker 02

  And Rachel Carlson.

• 0:25Regina Barber?

  With our biweekly Science News roundup, featuring the hosts of All Things Considered. And today, we have the always fun Ari Shapiro. We're gonna miss you, Ari.

• 0:33Speaker 03

  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 gonna tell me about some mysterious red dots in space.

• 0:43Speaker 02

  Yeah, and how the brain might fill in missing information.

• 0:47Regina Barber?

  And lastly, you'll love this, Ari, the wiggly world of octopus arms.

• 0:50Speaker 03

  Eight times the fun.

• 0:52Speaker 02

  Exactly.

• 0:53Regina Barber?

  All that on this episode of Short Wave, the science podcast from NPR.

• 1:01Speaker 00

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• 2:05Speaker 03

  OK, to kick us off, tell me about these red dots in space. I'm imagining like intergalactic acne. What is it?

• 2:11Regina Barber?

  Well, let's start at the beginning, Ari. The universe probably started with the Big Bang.

• 2:15Speaker 03

  At the very beginning.

• 2:16Regina Barber?

  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.

• 2:33Speaker 02

  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.

• 2:49Speaker 05

  It would be like checking on your little kid and finding a fully grown adult.

• 2:54Regina Barber?

  That's Bingjie 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.

• 3:02Speaker 03

  What does her team think these red dots are?

• 3:04Regina Barber?

  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 Anna DeGraff, says that our existing models really just don't explain what's going on in this specific case.

• 3:18Speaker 06

  So any normal star or galaxy model or a black hole model does not fit the data, essentially.

• 3:25Speaker 02

  So they needed a new model to explain the 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.

• 3:41Speaker 03

  I didn't know black holes could have an atmosphere. What does that mean exactly?

• 3:44Speaker 02

  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.

• 3:57Speaker 03

  Do they have ideas about how that might work?

• 4:00Regina Barber?

  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 Tal 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 supermassive black holes. So she thinks more work needs to be done.

• 4:25Speaker 03

  OK, let's pivot from black holes to holes in information in the human brain. What's the second story?

• 4:32Speaker 02

  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.

• 4:42Speaker 03

  So like the brain fills in the gaps to say, run?

• 4:45Speaker 02

  Exactly. And in that case, that brain feature is really helpful. But sometimes, in the case of things like optical illusions, the brain perceives objects that aren't actually there.

• 4:55Regina Barber?

  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.

• 5:04Speaker 02

  So Ari, I want you to look at an example of what the researchers showed the mice.

• 5:08Speaker 03

  Okay.

• 5:08Speaker 02

  It's called the Kaniza illusion. And tell me what you see.

• 5:11Speaker 03

  It looks like three black Pac-Mans

• 5:15Speaker 02

  Yeah.

• 5:16Speaker 03

  heading for a threesome towards each other.

• 5:19Speaker 02

  Okay.

• 5:20Regina Barber?

  No.

• 5:21Speaker 02

  Honestly, I like that description. A lot of people see a triangle when they look at it.

• 5:26Speaker 03

  Oh, okay, yeah, because like the gaps between the Pac people's mouths makes a triangle. Yeah, got it.

• 5:32Speaker 02

  Yeah, exactly. So to a lot of people, it seems like there's a white triangle on top of those black Pac-Man circle things.

• 5:38Speaker 03

  Mm-hmm.

• 5:39Regina Barber?

  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.

• 5:55Speaker 02

  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.

• 6:10Speaker 03

  So what can researchers do with that information now that they've identified this like specific brain circuit?

• 6:16Speaker 02

  One of the study authors, Hee Young Shin, says with a lot more work, and of course, work on humans, this could help researchers understand mental disorders that affect perception.

• 6:26Speaker 07

  The most famous example of that is schizophrenia, but also autism, ADHD, Alzheimer's, and the other diseases.

• 6:34Regina Barber?

  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.

• 6:43Speaker 03

  OK, third story, octopus arms. Take it away.

• 6:47Regina Barber?

  OK, Ari, so this new study came out in the journal Scientific Reports, and it's all about how octopuses use different arms for different tasks.

• 6:54Speaker 02

  Scientists analyzed a bunch of videos of octopuses in the wild, and they were like, great, what's each individual arm doing here?

• 7:01Speaker 08

  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.

• 7:10Regina Barber?

  That's Chelsea Benes. She's a field biologist at Florida Atlantic University and a co-author of the study.

• 7:15Speaker 03

  Sounds like a lot of octopus content to go through. What did they find?

• 7:18Regina Barber?

  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.

• 7:51Speaker 09

  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 messing up their behavior.

• 8:08Speaker 03

  Huh. OK, 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?

• 8:14Speaker 02

  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.

• 8:34Speaker 03

  They're not octopi?

• 8:35Regina Barber?

  I think it's both, right?

• 8:35Speaker 02

  I think it's both.

• 8:36Speaker 03

  Anyway, regardless, I look forward to watching.

• 8:39Regina Barber?

  Ari, you are such a great science nerd, and you are always welcome on our show. We're going to miss you.

• 8:45Speaker 02

  We'll miss you, and we love having you on for now.

• 8:47Speaker 03

  I love nerding out with you. Thank you for enlightening me every week.

• 8:50Regina Barber?

  Aw. You can hear more of Ari on Consider This, NPR's afternoon podcast about what the news means for you.

• 8:59Regina Barber?

  This episode was produced by Hannah Chen and Jordan Marie Smith. It was edited by Burley McCoy and Patrick Jaren-Watanen.

• 9:06Speaker 02

  Tyler Jones checked the facts. Tiffany Vera Castro and Patrick Murray were the audio engineers. I'm Rachel Carlson.

• 9:13Regina Barber?

  And I'm Regina Barber. Thank you for listening to Short Wave, the science podcast from NPR.

• 9:25Speaker 04

  Stay tuned for the following announcements and messages from our sponsors.