Ep 113: Cephalopods: aliens among us (with Danna Staaf)
Credit: Josh Weaver
Does biological plasticity have a cost? Are there evolutionary consequences of plasticity and of organisms acting on their environments?
In this episode, we talk with Danna Staaf, a science communicator and marine biologist with a lifelong love of cephalopods. Danna earned a PhD from Stanford University studying baby squid, and she has written several cephalopod-themed books. Our conversation focuses on Danna’s most recent book, The Lives of Octopuses and Their Relatives: A Natural History of Cephalopods, a beautiful exploration of the diversity of these wacky, wonderful creatures. We discuss cephalopod evolution, morphology, and reproduction, focusing on several fun facts that you can pull out at your next dinner party.
Cover photo: Keating Shahmehri
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Marty Martin 0:07
So Art, what do you think it would be like to have more than one brain?
Art Woods 0:11
Hmm, half-baked philosophical idea or a leading question where I'm supposed to say sometimes Marty, you seem so smart that you must have multiple brains?
Marty Martin 0:20
Definitely the first but it's so sweet of you to suggest the other.
Art Woods 0:24
Hmm not really what I said.
Marty Martin 0:25
Bizarrely some of the species that feature in our episode today, the cephalopods, do have multiple brains, nine of them, in fact. Octopuses, for instance, have a brain in the middle of their bodies near their mouse along with eight others where each arm attaches to the body.
Art Woods 0:40
Just how these complex bundles of neurons collectively decide what to do has intrigued and mystified biologists for decades.
Marty Martin 0:46
In some cases, these distributed brains must all be in sync, such as when animals sense threats and change the color and texture of all their skin in a coordinated manner.
Art Woods 0:56
But in other cases, arms might have minds of their own. Just search for videos from Peter Godfrey-Smith on the denizens of octopolis.
Marty Martin 1:04
In this unique place, off the coast of Australia, where normally solitary octopuses gather in very large numbers. Peter is recording animals mostly focused on one task, say protecting a piece of food.
Art Woods 1:15
But the same animal's simultaneously reaching out with one arm to do something else,
Marty Martin 1:19
You know, when watching the videos, I thought of what it must be like for a newbie urban dog walker.
Art Woods 1:24
Right. Maybe most of your dogs behave well and walk down the street in an organized way. But there's one or two, let's call them challenging pooches, that pull you in the whole pack towards every flower and signpost
Marty Martin 1:36
And the videos are kind of funny. It's like the octopuses have no idea what their arms are up to.
Art Woods 1:41
You know what I find most amazing about cephalopod intelligence is that besides being so distant from us, evolutionarily speaking.
Marty Martin 1:48
-right, 650 million years since the most recent common ancestor-
Art Woods 1:51
Is that squids, nautiluses, and octopuses tend to live for just two to three years. Some can make it a bit longer, but even the giant squids that Jules Verne popularized in 20,000 Leagues Under the Sea probably die at the ripe old age of five.
Marty Martin 2:06
Yes, that's crazy, because a main argument for the evolution of sophisticated primate cognition involves relatively long lives and complex social systems. The logic is that only evolutionary lineages that mature slowly and invest heavily in a few offspring should also invest in a sophisticated and complicated organ, like the brain. It's supposed to take years to learn complex behaviors and the social mores associated with group living.
Art Woods 2:31
Mhhm. And some of us never do.
Marty Martin 2:34
Which is exactly why cephalopod intelligence is so cool and surprising. They achieve it so quickly in their lives, that they must use it for quite different things, probably coordinating those arms.
Art Woods 2:45
And don't forget about avoiding being eaten by most everything. After all, with some exceptions, they're just big bundles of flexible tasty carbon floating in a predator rich world.
Marty Martin 2:55
On today's show we talk about cephalopod intelligence, morphology, behavior and ecology with Danna Staaf, author of the new book The Lives of Octopuses and Their Relatives: A Natural History of Cephalopods.
Art Woods 3:06
Danna is a science communicator and marine biologist with a PhD from Stanford University and author of several other books including Monarchs of the Sea, and The Lady and the Octopus: How Jeanne Villepreux-Power Invented Aquariums and Revolutionized Marine Biology.
Marty Martin 3:22
We touched on this latter book a bit in the show, and I can't wait to read it because Jeanne Villepreux-Power is one of those amazing people in the history of biology that we just haven't heard enough about.
Art Woods 3:31
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Marty Martin 3:41
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Art Woods 4:02
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Marty Martin 4:10
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Art Woods 4:19
I'm Art Woods
Marty Martin 4:20
And I'm Marty Martin
Art Woods 4:21
And this is Big Biology.
Marty Martin 4:36
Danna, welcome to Big biology. We're really excited to have you on the show today to talk about your new book The Lives of Octopuses and Their Relatives: A Natural History of Cephalopods. Honestly, it's an absolutely beautiful book to look at, which makes podcasts for such things unfortunate. So I encourage listeners to go find a copy and see for themselves fantastic pictures that are there.
Art Woods 4:56
So just to get going, tell us about how did you get into cephalopods in the first place? Clearly, it's a love. But how did you get there?
Danna Staaf 5:03
Thanks so much for having me. I'm really excited to talk about this book with you guys. And yeah this is a lifelong thing for me. So when I was 10, approximately, my family went to the Monterey Bay Aquarium, and I met an octopus. And that was sort of the end of the story also, but also the beginning of the story, because they have a Giant Pacific Octopus, at least one on display pretty much all the time. I mean, anybody who's been there has seen the octopus. And this was the first time that I had ever seen an octopus alive. And it completely captured my attention. Now, I was already really into animals and nature generally. I would watch the squirrels and the ants in my backyard. And I was into aliens, too. I thought aliens were really cool and not like into conspiracy theories, just like, hey, it would be really cool if there was some really super weird shaped things living on another planet. And then I saw this super weird shaped thing living on our planet. And it was like, it brought everything together for me. It was like, Okay, this, this is it!
Art Woods 5:59
The aliens are among us.
Danna Staaf 6:00
And yeah, I was just completely captivated. It has these eyes that look back at you. Like there's clearly a sort of interchange of interest happening when you're looking at an octopus that's looking back at you. And yet it's so different. And it's so similar. And yeah, I was just totally fascinated. We went home. So my mom was very sweet. She bought me a little octopus postcard in the gift shop, so that was great, but I wanted a real octopus. And so I made quite a stink about it for a while. And finally my dad and I figured out that we could get a secondhand saltwater aquarium, we could pool enough resources to pay for it. And that you can keep small pet octopuses, much smaller than the Giant Pacific Octopus like smaller than the palm of your hand. And I was in LA, I grew up in LA. And so one of the nice things about being in a big urban center is that there are tropical fish stores, and I could bike to one that occasionally had octopuses. So I got a pet octopus. And at school, I became the girl with a pet octopus. And basically ever since then, that's like the thing everybody has known about me for 30 years, and I get octopus T shirts. And I get octopus mugs from people who like barely know me. It's very sweet. So that first octopus that I got, I named her serendipity, which was the name of a sea monster in a children's book that I really liked. But of course, it also has its own meaning. It's, you know, a sort of wonderful coincidence, a wonderful happenstance, which was kind of like my meeting with the octopus.
Marty Martin 7:21
Wow, that's perfect. That's almost like a story book. Ok, I think we should start a chat today in the fairly obvious place of what is a cephalopod? I love the sort of shorthand, colloquial definition or vision you gave of these things-attaching your limbs to your lips. So that's about as vivid as it gets. But is that enough to describe what's this?
Danna Staaf 7:48
The question of what is a cephalopod comes up all the time. And so I do have this sort of imagine that you could take your arms and legs off of your body, and stick them onto your lips. That's the way an octopus or squid is organized. Instead of having the head on top of the body and the limbs attached to the body, they have the head between the limbs in the body. And that's where the word cephalopod comes from, it means head foot. They have their feet or their limbs attached directly to the head. But of course, that's superficial in a way, because if you did that with your body, you would still be full of bones. And octopuses and squid have no bones whatsoever. They are invertebrates, and they've been evolving on a totally different trajectory from us for more than 500 million years. So obviously, there's a lot of other differences as well. And another way to think about them coming from a different angle, because the groups that they're most closely related to are slugs and snails, is that they're like slugs with jet propulsion. They're like the snail that turned into a fish. And all of these comparisons certainly are not perfect, but they're different ways of trying to get at what is this super weird animal?
Marty Martin 8:55
Right, right? Because within those cephalopods there are groups, right sort of different types of them, and their morphology is quite different, right?
Danna Staaf 9:04
Right. It can vary quite a lot within this, like, okay, you've got your limbs attached to your head, and then a mantle also attached to your head, that's the body that has all the organs in it. But then, on top of that, some of them still do have external shells like a snail, those are the nautiluses, that they live in. And then some of them are shaped very much like fish. They're very hydrodynamic and very fast swimmers. And they're good at hunting down prey. And then some of them, like the octopuses, have almost no shape at all. And they're just sort of like almost like liquids flowing around and adapting to whatever shapes are around them.
Art Woods 9:36
So take us back, you mentioned 500 million years or so, take us back to the origins of cephalopods. So what did the very earliest ones look like? And what's the process of differentiation from the other mollusks? And do we have, you know, fossil evidence of all of this?
Danna Staaf 9:52
So we do have some really cool early fossils of cephalopods. We still have to make guesses because that's how paleontology works is that we never have every single space filled in, basically. But we see the earliest cephalopod fossils, in a period of time called the Cambrian. And the Cambrian is famous for something known as the Cambrian Explosion, because it was a period of time when animal diversity on Earth was just getting wild. Before this, there were sponges, and there were a jellyfish, and there were some other things that we don't really have names for it, and they were all relatively small. And then, in this period of time, we got to see kind of the explosion of most of the groups of animals that we have today. So this is not only when we see the earliest cephalopods, but also the earliest sea stars and sea cucumbers and sea urchins, stuff like that. Also, even the earliest vertebrates, our own ancestors, although they looked like little worms, like nothing like a vertebrate today, and lots of other groups showed up in this time, in the Cambrian.
Danna Staaf 10:55
And so with the cephalopods, we're part of this group called the mollusks, which are soft bodied animals that build hard shells. And so there's lots of little shells, they all started out quite small, little shell fossils. The great thing about shells is that they're hard and they fossilize relatively well. And the way that paleontologists identify cephalopod shells as different from snail shells or clam shells, or the other groups that were even before snails and clams is that their shells, the cephalopod shells, have chambers in them. So inside the shell, there are walls separating it into rooms. And the reason that's such a big deal, and we still see it in the chambered nautilus, which is the living cephalopod that has a shell, is that in those chambers, they could actually swap out liquid for gas and become buoyant. And long before tentacles or suction cups or camouflage or anything, that was the big cephalopod innovation, was while the snails and clams were sitting on the seafloor, burrowing in the seafloor, they were floating above it, because they had these buoyant shells.
Marty Martin 12:00
So with those early cephalopods, I mean, what kind of diversity are we talking about? When did the octopuses in the squids and you know, all the things that we all know today when did they show up?
Danna Staaf 12:09
Quite a lot later, really, the earliest octopuses and squids and cuttlefish came even later. They're not coming along until the Mesozoic, really, which is dinosaur time. And the Cambrian is hundreds of millions of years before that. So for quite a long time, it was all shelled cephalopods, but there was, there were a couple of groups that fossil hunters will know, the Ammonites and the Belemnites, in particular. So the Ammonites were, in some sense, the first big cephalopod success story, but I'd say they're actually the second one, because those early cephalopods that were very tiny, by 50, 100 million years after they first show up in the fossil record they were evolving huge forms. And so there were these very early giant cephalopods
Art Woods 13:00
Like meters long, right?
Danna Staaf 13:02
Yeah, like taller than a basketball hoop. And those were actually the first big animals on planet Earth. It's like, I cannot emphasize enough how cool that is, and how many more people should know about it. Because it's way before dinosaurs. And it's way before most of the giants like the prehistoric giants that we think about, because there was nothing on land. So there's no dinosaur to compete with them at all at this time. And in the water, there's no big fish. They are the biggest animal there. And we don't know if they were like super predators eating all the trilobites, or if they were maybe more like super scavengers, just picking up stuff after it died. But they were super, they were very big. So that's success story number one. And then after time, and after evolution of more diverse forms, and especially after the evolution of more fish that were getting bigger and getting jaws that can grab and crunch shells. That's when we see the Ammonites start to show up. And those with those coiled forms that became super abundant, that are really common in fossil collections. There's small ones, there's big ones, there's tightly coiled ones, there's loosely coiled ones, there's ones that are coiled, like ice cream cones, like they became wildly diverse.
Art Woods 14:11
And the implication is that the shells are a defense against fish.
Danna Staaf 14:14
Yeah. And in particular, it seems to be that the coiling of the shells, because those early giants have straight shells. I forgot to say. So they had long, straight shells like super long ice cream cones with a squid stuffed in one end. And then the Ammonites coiled their shells. And there seems to have been an advantage to that, like a tighter coiled shell is maybe more difficult for a predator to crack or it's easier to maneuver in the water, because certainly you can imagine this super long, straight shell you can't swing that around very quickly if you've got a shark coming after you.
Art Woods 14:45
Yeah. Okay, so Ammonites, huge success, but they're gone. So what happened to them?
Danna Staaf 14:51
Right, so they did and now we're going all the way through the Mesozoic Era, dinosaur time, ammonites continued to proliferate to diversify. There are ammonite shells with cool spines on them and ammonite shells that look like they were tied in knots. There's just like endless ammonite diversity. And at the same time, the earliest squid and octopus ancestors were also evolving in the oceans now. And so now we've got dinosaurs on land, marine reptiles in the water, mosasaurs, ichthyosaurs, stuff like that, and a lot of those marine reptiles are just chowing down on cephalopods like they are the snack of choice for most of the marine predators in the Mesozoic, and I will, jump forward to say that that is still very true today, pretty much anything that can catch a squid will eat it, including like seabirds and wolves, anything. So in this time, they were doing great, as sort of central to the food web. So not top predators, and not the bottom of the food but making all these connections. They're eating small stuff and getting eaten by big stuff. So like really central to the ecological connections there.
Danna Staaf 15:50
And then, we had this really bad day on planet earth when a giant rock smashed into the Yucatan Peninsula. And I was actually just reading a really awesome book about it called The Last Days of the Dinosaurs by Riley Black. And it's and she just like lays it all out, like just what a very bad day it was. And so in the ocean at first, it was not that bad, because there were no fire storms. Like they were sort of buffered by the water that they were in. But in those days after the impact, and this is the end Cretaceous impact the extinction that ended the non-avian dinosaurs, oceans really fell apart. There was a lack of sunlight to fuel the bottom of the food web. There was also acid rain that was making the waters more acidic. And that pretty much collapsed a lot of the food web that depended on plankton, which ammonites seemed to have done especially when they were babies. And so the early life forms of ammonites as we understand it couldn't really survive in those days after the impact. And for whatever reason, the ancestors of octopuses and squid and nautiluses were able to squeak through. And there's probably some aspect of chance there and luck and where they found themselves, but there's also thought to be the for the nautiluses they also had coiled shells, like ammonites, but they had larger eggs, they still do today lay fairly large eggs. And it's thought that once they're born, they might have been able to scavenge right away, which would have made them less dependent on that planktonic food web.
Marty Martin 17:36
Okay, so let's move to modern times, but I gotta, I gotta ask how did those first cephalopods get so big? Was it this trick of buoyancy that allowed them to become giant like that?
Danna Staaf 17:47
Exactly. Yeah so a snail for example, is kind of limited in size, because the bigger it gets, the bigger its shell needs to be. And the bigger its shell is, the heavier it is, like that's a solid thing that you got to carry around. And cephalopods broke that connection, because their shell every time it gets bigger, they can add another chamber full of buoyant gas. And so it can get just bizarrely large at that point. And also, the larger they were getting, the greater the range of either prey or dead prey, they could scavenge. And so that really seems it was that buoyancy. That was their first like, okay, like freedom from constraints really.
Marty Martin 18:26
Hmm interesting. So I mean, it's always a paradox for me because things get really, really big, and then they also disappear. Right? We still, as you say, we have the nautiloids. But why don't we have any giant shell nautiloids or things like them now?
Danna Staaf 18:39
I know
Marty Martin 18:41
Wouldn't that be cool?
Danna Staaf 18:42
It would be very cool. But we actually didn't get, let me see. I'm thinking about giants now. So they were some pretty big ammonites in the day and so they were able to make pretty big shells. There's one called Parapuzosia that was in I'm not gonna remember the exact year, but I think it was Jurassic, it was sometime in the Mesozoic, or maybe even Cretaceous actually, I think it was later on. So like way after those early, early straight shell giants we had this coiled shell giant and its shell was big enough that you can climb inside.
Art Woods 19:13
Wow
Danna Staaf 19:14
So clearly, there was a capacity for even the coiled shells to get quite large. I think that those animals went extinct, obviously, and for whatever combination of chance and like new ecosystem shapes that came about in the modern times post asteroid they just couldn't. That's not a form that works so the cephalopods without shells can now get giant so we have giant squid, we have colossal squid we have Giant Pacific Octopuses, but the shelled ones, there's a certain niche that they can occupy. And that's where they are.
Art Woods 19:51
Yeah, one more question about the shells and buoyancy. So how do they secrete the gasses into these spaces?
Danna Staaf 19:58
I do, and it's so cool!
Art Woods 20:01
Oh, excellent.
Danna Staaf 20:08
Ok so the living animal lives in the outermost chamber of the shell. So you've got a shell with multiple chambers in it. And as they grow, they'll make a new chamber and sort of move into that one and seal off the old one. But there's always an opening in each wall of the sealed off chambers. And through that opening, there's this tube of flesh. So the animal's living flesh does extend all the way back to the center of the spiral or the or the end of the shell, if it's a straight shelled cephalopod. That little tube is called a siphuncle, which is Latin for little tube, and it has blood in it, just like the rest of their body, it's part of their circulatory system. And it's through the skin and the blood that goes through each chamber that they're able to adjust the amount of gas and the amount of liquid.
Danna Staaf 20:56
Now, when I was a kid, I thought there was some sort of like active pumping, like somehow they're like squeezing the siphuncle and pumping gas into the shell. But it turns out that the gas diffuses passively, because what they can do is change the salinity of the blood in the siphuncle. And so they make the blood extra salty. And when the blood inside is extra salty, it's saltier than the fluid, basically, the seawater that's in the chambers, and it draws that water in. And so that reduces the pressure in the chamber itself, which pulls gas out of solution. And so their blood has dissolved gasses in it just like ours, we have dissolved oxygen, dissolved CO2 in our blood that's how we're doing gas transfer and breathing. And so those dissolved gasses in the blood of the cephalopod get pulled out of solution, as the salty blood is pulling liquid in.
Marty Martin 21:49
That's phenomenal.
Art Woods 21:50
That's super cool.
Danna Staaf 21:51
Does that make sense? It's totally bonkers.
Art Woods 21:54
Yeah. It's like using osmosis to like create pressures to drive the gasses. That's awesome.
Marty Martin 22:00
Okay, as promised modern times, that was a modern time clearly there are nautiloids that are doing things like that.
Danna Staaf 22:05
There are. That's how people figured it out. Right? They didn't figure that out by studying fossils. Right?
Marty Martin 22:10
That would be impressive if one could do something like that. Okay, so another very conspicuous thing of, I think the first cephalopods that come to the average listener's mind- arms and tentacles, what's the difference between these things? And why do they have the numbers and arrangements that they do?
Danna Staaf 22:28
Right. So the first step is to give you a cocktail party fact that you can wow people or really annoy people depending on your friends' personalities. Octopuses do not have any tentacles, they have zero tentacles-
Marty Martin 22:42
Ah
Danna Staaf 22:43
-in the technical scientific definition. Now, if you pull out just like a dictionary, Oxford, Merriam Webster, I think that one of the definitions of tentacles would probably include the arms of an octopus, because it's a casual usage, which is fine. But if you want to be scientific, arms are the appendages of a cephalopod that have suckers on their whole length from the base to the tip. And they're not elastic, they can't stretch and contract, they're a certain length. So if you're looking at the definition, or a species description for a given octopus, they'll tell you how long the arms are, because they're going to be that long, more or less unless an eel bites off the tip of one or something like that.
Danna Staaf 23:25
Now tentacles are elastic and squids and cuttlefish have tentacles, they have two tentacles that are often retracted in little pouches. And when they're hunting their prey, they'll shoot out really fast. It's called a tentacular strike. And they only have suction cups on the tip of them, which is called the club or the manus. And the rest of it has no suction cups. It's just this like rubber band almost, that can shoot out really fast, the ends grab on to the prey, and then they retract and pull it back in. And then squids and cuttlefish like octopuses have eight arms, and they use those arms to grapple to cling on to the prey as they're eating it, biting it, doing whatever they need to do.
Danna Staaf 24:05
That said, nautiluses have no suction cups, and they have dozens, 60 to 90 tentacles. We call them tentacles, even though they're not quite like the tentacles of a squid or cuttlefish. They do have an ability to sort of retract and pull back because they have a sheath around them. They're also sensory and sticky, and honestly, we need to study them more because scientists are still figuring out what nautiluses do with their tentacles, what their abilities are to smell and taste and all of this cool stuff that they do. Oh, and there's a fun way to remember it too. The word arm is shorter than the word tentacle, and arms are shorter than tentacles, in a single animal. So like a squid, for example, you spread out all of its appendages and the tentacles are the two long ones and the arms are the eight short ones.
Art Woods 24:57
I'm heading to a party tomorrow night. I'll try all this out. Yeah we'll see how far I get you look worried.
Marty Martin 25:03
Depends on how many biologists are at this party.
Art Woods 25:05
It is gonna be a biologist party.
Marty Martin 25:08
Yeah, okay. Okay.
Art Woods 25:09
What about suckers? So, you know, that's another thing, I think, that immediately leads to mind we think of octopuses. So how, how does suckers work? And what are they?
Danna Staaf 25:16
They're so cool! And there's so many different kinds. The octopus sucker it's a suction cup, essentially, and the back of it is attached right to the skin of the arm. And it is so sensitive, and under such detailed muscular control, that not only can it suction on to things like we think of a suction cup typically doing, but they can actually bend the edges and use it to grab things, almost like little fingers. So in a of fuzzy but sometimes useful analogy you could think of the arm that an octopus has is kind of like our arm, and then it's covered with sections cups, which are sort of like fingers because they use them to grab and manipulate things, as well as if they're trying to avoid being pulled out of somewhere, or if they're trying to pull up clamshell or something open, then they'll just use the straight up suction, which itself is really impressive the amount of suction that they can exert.
Danna Staaf 26:13
But then squid and cuttlefish suckers are a little bit different. They're on stalks. So there's actually like a little stem almost between each section cap and the arm of the squid or the cuttlefish. And they're less able to grab and manipulate things. But they are also super, super strong and able to hold on to things. And all of these suckers are very powerful in terms of their sensory ability, they're able to detect sort of the chemical surroundings, they're almost like tastebuds. They can also recognize self from nonself, which is why octopus hackers don't stick to themselves when their arms are moving over each other. They're bizarre.
Marty Martin 26:51
That's great. Okay, why there's so much to hit with the sucker side of things. On the sucking piece of suckers, I learned from your book that they have a glue that they can produce as well. There's some variant of mucus, talk about that. How common is that and are they using it for adhesion only or what are its own purposes?
Danna Staaf 27:10
Okay, so mucus is very important to mollusks generally. This is one of the first things that I learned. So you have to think about a snail, a slug, sliming, across the leaf, they're very mucousy animals. And so yeah, cephalopods produce mucus, their skin is generally covered with a thin layer of it. It's part of what protects them, if they do come out of the water, crawl around on the tide pools and stuff. Some species have evolved glue. And it's not related really to the stickiness of their suction cups. It's a different phenomenon that they use sort of in different ways.
Danna Staaf 27:43
So for example, the pygmy squid, which is the tiniest adult cephalopod on the planet. It's very adorable, it's smaller than your fingernail. Those have in addition to the teeny, tiny suckers on their arms. They have a fairly large section organ on their mantle, which is the main part of their body. And they use that organ to just stick themselves on the seagrass, which is where they live in seagrass beds. And they're sit and wait predators. So they stick in place and they wait for yummy looking shrimp to come by, for the most part. And that glue that they secrete to stick themselves to the seagrass, they can also secrete another one to sort of break the adhesion. So it's almost like a multipurpose, like they can stick themselves down with it, and then they can very quickly unstick themselves. And that stuff is still being studied. There's a lot that we don't know about it.
Art Woods 28:32
I was gonna say, sounds like fertile ground for bioinspiration of new adhesives. Is anybody doing that?
Danna Staaf 28:37
Yes, it is. Yeah, yeah. That's definitely one of the areas that material scientists engineers are looking into for biomimesis.
Marty Martin 28:47
And it's not all suckers either. Right? I mean, I think we have to mention that sometimes they have these hooks, right. Certain species instead of suckers, it's big hooks. Which species have these things?
Danna Staaf 28:57
So the colossal squid is probably the most famous, they have these big hooks on their arms and on their tentacles that can actually rotate. So there's enough flexibility in the flesh that they can rotate, in position, which helps them to hold on to their prey. And so these are big, big, big squid that are catching pretty big fish and suction, one could imagine the fish might be strong enough to just break that. So by having these, basically being covered with fishing hooks, they can really grip onto and hold their prey. And with the twisting ability of the hooks probably means that instead of getting just ripped out, if the fish is fighting, they can hold on to it and keep their grip.
Art Woods 29:40
Yeah cool. I wanted to turn to a question about internal physiology. And this is something I learned about when I was having my first technician job after I graduated from college. It was a lab where some some people were working on neurons and neurobiology, and they were working on these giant axons in squids And, just for the listeners, tell them about what these giant axons are, and the role they played in the development of of neurobiology, because they've actually been really important, right?
Danna Staaf 30:09
They have been super important. So squid and their ancestors basically lost their shell. They lost what you would think of as their protection against predators. And as they were evolving away from having a hard external shell to hide in, they were evolving a new strategy, like a new approach to escaping predators. And that's jet propulsion. So they can swim by jet propulsion, which is quite rare in the animal kingdom, there's really only one other group of animals, the salps, that does it at all. And they do it by filling their bodies with water and then squirting that water out of a siphon, which is a small opening, and that pushes their body in the opposite direction. And the way they squeeze the mantle, to push out that water, is through muscles, and the muscles are being controlled by nerves. And if they can squeeze really hard, really fast, kind of all those muscles in concert, then they can create something called an escape jet that's a really fast, really effective jet away from a predator or a threat of any kind. And so squid create that escape jet using something called a giant axon.
Danna Staaf 31:16
And so there is sometimes some confusion because there are also giant squid in the world. Does the giant axon come from giant squid? No, all squids have a giant axon and it is giant in comparison to the other axons that neuroscientists were used to looking at, like itty bitty little mouse axons and things like that. It's still small, like, you can see it with the naked eye, but it's not like as big as your arm. And you know, it's a thread, it's a string going the length of the mantle of the squid, but it is so much bigger than the sort of microscopic cellular stuff that neuroscientists had alternative to that, that when this giant axon in the body of squid was discovered, it really kicked off the whole field of neuroscience. I shouldn't say that it was better than the alternatives, because nobody had developed any alternatives.
Art Woods 32:07
Everything else was too small at the very beginning, yeah.
Danna Staaf 32:09
Right, we didn't really know very much, because this is also sort of early on in microscopy. It's not like scientists then had a really clear view of how the nervous system worked, because you just couldn't see it. And then they started opening up squid and actually being able to see the size of this axon, the shape of it, where the dendrites connected, so it's connections to other nerves. You could stimulate it and see what it did to the muscles around it. And it really, yeah, it really was a game changer in terms of understanding not just squid, but how nerves work in the entire animal kingdom. Which just goes to show that even though they kind of seem like aliens, cephalopods are definitely related to all the rest of us. They have nervous systems, just like everybody else.
Art Woods 32:51
So I think, you know, one functional question is why they have large axons? And my understanding is it has to do with the speed of conduction of action potentials, right? So the bigger the diameter, the faster the signals can go. And so I could make up a story like, you know, they have to be able to respond ultra fast to threats, and maybe contract their mantle and create this jet to get away from danger. But you could say, well, there's lots of things in the world that have that exact problem. And so why don't other things also have giant axons?
Danna Staaf 33:19
Right, and it's a great example of convergent evolution actually. Sorry, not convergent evolution, what's the word I'm looking for? It's like
Art Woods 33:26
Like alternative solutions to the same problem?
Danna Staaf 33:29
Yeah, it's like similar problems that we come up with sort of similar but also different solutions to over evolutionary time because vertebrates, fish, mammals, birds, all of us, we also evolved to conduct super fast nervous signals. And the way that we've done it is through myelination, so by insulating the nerves. And that insulation around our nerves around our neurons makes the signal travel much, much, much faster. And so in a way the giant axon of a squid is sort of their parallel path, that's what I'm thinking, talking about parallel evolution.
Art Woods 34:03
Yeah they don't have myelin.
Danna Staaf 34:05
Yeah, they don't have myelin, they don't have insulation. And yet they were evolving on this trajectory that we think of as almost a vertebrate trajectory, being able to need to react quickly move fast, be very active, like very different from this sort of snail, clam, slug trajectory of evolutionary history. And I think what's so cool is that, you know, evolution just happens when the pressures are there. And when there's enough material for natural selection to work on. And in the case of squid, with their invertebrate background, their molluscan heritage, the raw materials for natural selection to work on to end up creating this other way of transmitting signals really fast. So you can either do it through myelination or through making a really big axon.
Marty Martin 34:53
Well, this is a good time. It almost feels like I'm being prompted to mention vision here. Because you know what, what wonderful What better case of convergent evolution? Can you talk about than vision in these guys. So tell us about the key pieces that sort of make cephalopod vision interesting with respect to vertebrate vision.
Danna Staaf 35:11
Totally so the ancestors of modern cephalopods and in particular, I'm talking now about the group of cephalopods called Coleoids, which is a word that means sheath. So that's how I remember it, it's all of the octopuses and squid and the other animals that sheathed their shells, brought them internal, and then reduced them. The ancestors of that group of cephalopods were really evolving in parallel with fish, filling a lot of the same niches competing for a lot of the same prey also eating each other constantly.
Danna Staaf 35:39
And so there was a lot of pressure and continues to be a lot of pressure to be a very agile, reactive animal. And a strong sensory capacity tends to come with that. And vision in both cases, was really important for spotting predators, spotting prey, seeing where you can swim in your environment that won't lead you to crash into a coral head or something like that. So their eyes evolved to give them this ability, essentially.
Danna Staaf 36:08
And so when you look superficially, at the eye of an octopus and the eye of a human, they look super similar. We have lenses, we have pupils, we have this array of photoreceptors at the back. And we have this complex nervous system to digest all that information and translate it for us. But then when you look more closely, you can actually see how the animals converged through different trajectories on a similar solution.
Danna Staaf 36:34
And in particular, the thing that always gets me is that the human and the vertebrate eye generally has a blind spot, because the way our eyes evolved, the nerves that are taking the signals from those photoreceptors at the back of our eye actually come out towards the front of the eye. And so they're inside our eyeball needing to get out to the brain. And so we have a little opening in the eyeball where they all gather together and come out to go back to the brain. And that little opening can't have any photoreceptors in it. So we can't see right there. And of course, it's not an issue for us, our brains have evolved to fill in that blind spot, and we're moving our heads, and we're moving our eyes, and we hardly ever noticed that it's there. But it's not something that you would put in it from a design perspective. If you were sitting down and trying to create an eye and the way cephalopods evolved, it didn't happen. Through whatever vagaries of chance and just stepping along that process, their photoreceptors evolved to the back of their eye with the nerves coming out the back already, so they don't have a blind spot, their nerves all gather together go straight into the optic lobe, that part of the brain that processes all that information.
Marty Martin 37:39
Right, right. So one of the things, I think the most remarkable and surprising thing from the book, again, my ignorance of cephalopods. They don't have cones, right? They don't have the ability to see color. So how in the world do they come to emulate, you know, all the various subtleties in their environment, when they can't even see one of the key things about the environment they're trying to resemble?
Danna Staaf 38:02
It is totally bonkers, from a human perspective. So if we could get out of our own brains just a little bit, there are a lot of ways that we can understand them.
Marty Martin 38:15
Be an octopus, okay?
Danna Staaf 38:17
You don't even have to be an octopus just like try to be a little less human.
Marty Martin 38:20
I can do that part.
Danna Staaf 38:23
So I think that one of the first things to remember is that the skin of a cephalopod has a lot of layers to it. The sort of main part that we think about, that we usually talk about, when we're talking about, how do they match their environment? How do they camouflage? Is they have layers of chromatophores, or organs that are connected to the nervous system again, so they can change at the speed of thought, essentially. And each one is like a little pixel almost, it can turn on and off. And when it's on, you see the color red, brown, yellow, and when it's off, it's so tight, usually can't even see the color at all. So that's those, that's cool, that's how they're creating colors and patterns on their skin. But there are other layers as well. And one of the layers underneath that is called leucophores. And those are "leuc," means white, because they're not white, but they are basically just default reflecting whatever's in their environment. And so they have this layer that really helps them to match what's around them, because it's just bouncing back the light that's around them. So there's that that's happening. There's also a layer of iridophores, which are reflective and, they are usually, we think of them as making like blues and greens and purples sort of like a peacock tail. And it's a similar structural color instead of the pigment that's in the chromatophore, they're refracting and bending light to create those sort of iridescent colors.
Danna Staaf 39:42
And so the combination of all of these different abilities that we look at and what we notice most is color because we are super tuned into color vision. But there's a lot of other stuff to notice. And that is, the pattern and the reflectance and even polarization which we can't perceive without special equipment or polarized sunglasses, but that the cephalopods are able to perceive polarized light. And so there's a lot going on there that we're not perceiving. And we're just so tuned in to color that we tend to pick out, like, "Hey, you're matching the color really well." But if we look at it really closely, often the best match might be the pattern. And because we're just seeing is such a good match, our eyes are sort of filling in our brain is filling in like, "Oh, also the color matches really well." But you know maybe it's not always that good.
Danna Staaf 40:25
And then it's also been found, and the details are still very much being worked out that the skin itself has photoreceptors in it. So it is, to a certain extent, actually getting information about what's around it, we don't know how much it's taking that on, it would be a huge stretch, like probably a stretch to the breaking point, to say that their skin is seeing. But it is definitely there's sensory input going into the skin as well as going out. And that probably is helping them too.
Marty Martin 40:57
That's crazy. But if if you know we think like an octopus, or we try to think less like a human, I mean, giving a little bit more latitude to what we would call seeing, you know, just using these photo pigments in consistent ways, but maybe not exactly all the same bells and whistles. That's absolutely amazing.
Danna Staaf 41:12
That said the scientists definitely have kept trying to find ways that they could see color without cones. It's like, Okay they don't have cones. But what if they could adjust the shape of their pupil over time to let in different wavelengths at different times? And then sort of integrate that information? Yeah, people get very creative with it. So we may yet find something that we don't know.
Art Woods 41:32
Super cool. Let's turn to some life history issues, maybe tell us about how they reproduce and sort of what this the schedule of reproduction is, and yeah, how does it happen?
Danna Staaf 41:42
Sex. This is great. I hope it wasn't obvious, but the neuroscience is a little bit out of my wheelhouse, because it's all reading. I have never- I patch clamped a cell more than like once or twice in my life. But my entire PhD thesis was on the sex and babies of squid. So I'm right here. One of the reasons that cephalopods have done very well in modern times and seem to continue to be doing well, on average, is that they reproduce fast with lots of babies and other exceptions. Now there are exceptions, but on average, a squid or octopus, most species live a year or less. So they're developing all the way from hatching out of their eggs to making eggs of their own. And often a matter of months. It is totally bonkers. Especially the big ones. So I was studying Humboldt squid for my thesis, and they get to be five, six feet long. And they're doing that in a year, maybe a year and a half, maybe two years for the really big ones.
Danna Staaf 42:41
And then they're laying, the Humboldt squid were laying, this is something that we discovered while we were working on them that nobody had seen their egg masses before. But we found one in the Gulf of California and calculated that it could have had a million eggs in it, half a million, two million, or even more. And that's all from one female, and she can make more than one of those. So that is a bit of an extreme case, the smaller octopuses like the species that I kept in my home aquarium, that one's not going to be laying more than maybe a few hundred eggs. But still, it's a few hundred eggs, like most of them are definitely hundreds, thousands of eggs that they're producing. And that fast generational turnover every year or so, and the vast number of offspring that they're producing, it really helps them as individuals as a species, I shouldn't really say as individuals, but like, it gives the species so much to work with. If the environment is changing, if there's a bad year, or a good year, or there's not a lot of resources, or predators are moving in or predators are moving out, there's this flexibility in their life history system, where they can take advantage of good times, lots of babies will survive. And in bad times, most of those babies will get eaten, but as long as a couple of them survive, the species keeps going.
Art Woods 43:57
So that sounds like a way of flooding local habitats and ecosystems with lots of babies and sort of rolling the dice and some of them are gonna die but there's alternative strategies, right in some species where they make very few very large propagules and they invest a lot of parental care. Is that also true?
Danna Staaf 44:14
Well parental care in cephalopods is so interesting, as is the size, and those are a little bit decoupled. Interestingly, so octopuses are known for caring for their eggs as females as mothers and I think that has gotten a lot of attention in the last 5, 10 years. The documentary My Octopus Teacher showed the female sort of devoting the end of her life to her eggs. There was a discovery of a mother octopus in the deep sea, who had brooded her eggs for four and more years without moving away or eating. And even just in an aquarium, if a Giant Pacific Octopus lays eggs, she'll stop eating and basically devote all of her energy to protecting them, keeping them cared for, but that's hundreds and hundreds of eggs still, in the case of a Giant Pacific Octopus she lays lots of strings of really tiny eggs. So it's an interesting case where there is parental care until hatching, at least, there's none after hatching, but also still quite a large number. But then there are animals like the nautilus that I mentioned that do lay quite large eggs and they don't care for them. But those eggs are large enough that the baby that hatches out just looking like a little baby nautilus. And it can start eating and scavenging right away, there's a lot of variation. And squid were thought to not do any parental care that was like, that's the octopus thing. That's what they do. And squid just lay their eggs and then pretty much die, like there's a lot of predators that will just come and feast at squid mating grounds, on the squid that have managed to lay their eggs. But then again, this is just relatively recently, in the last few decades, there'a a couple of species of deep sea and midwater squid that were found swimming around with their egg masses in their arms. And again, it's quite a lot of eggs, but they are clearly holding them with them, caring for them, keeping them away from predators.
Marty Martin 46:16
Okay, so I think it's time because there's so many questions we have, it's time to raise the most conspicuous thing about these cephalopods- how bright they are. And I love that we just finished talking about how insanely quickly they grow and mature and how reproductively prolific they are, because you're not supposed to get that kind of a pairing, right. I mean, you know, our cognition is supposed to be a manifestation of these long, developmental gestation periods and parental care thereafter, and all of that kind of thing, and it's consistent with the other primates. But the cephalopods don't play that game. What's your favorite story about cognitive sophistication? And what's your favorite explanation of why that happens in cephalopods?
Danna Staaf 46:59
I mean, I think the stories of captive octopuses climbing out of their tanks is just-it can be a little bit heartbreaking, because if they can't get back in, or if they can't get into another tank, they're gonna die. But there are just these amazing stories that aquarists tell where they get out of their tank, and they go into another tank to eat, they're like, "Oh, good, thank you for keeping this neck tank full of crabs, I will now go and have dinner. And then I will go back into my own tank." It's just it's so cool. You know, they are really good at adapting to their environment. And I think that that kind of brings us to the explanation, which is that we think of intelligence from our own perspective, as it's something that allows us to teach each other generation to generation, parent to child, grandparent to child even, and sort of build on that knowledge of those who came before and adapt to our environment in these complicated ways.
Danna Staaf 47:56
But cephalopods remind us that complex behavior and cognition can also be really adaptive over the short timeframe, over just a matter of weeks or months, by having a really flexible set of behavioral strategies by having the ability to learn from their environment, and to be curious about it, an individual octopus or squid increases its own likelihood of survival. And I think that that paired with the abundance of babies that most of them have, is really interesting. It's really valuable. There's a lot of animals that make a lot of babies, but that don't have very complex cognition. As far as we can tell, they tend to have pretty simple behavior. A lot of insects come to mind not to dunk on the insects, because there are some cool behaviors there as well. But a lot of them are not, they just kind of do exactly the same thing, more or less, from one generation to the next. And a lot of cephalopods have the ability to do different things to find different food sources to adapt to a different habitat or a change in the types of predators that they're exposed to.
Marty Martin 49:03
Right. There are some squids that are in really big social groups, though, right? I mean, they're big groups. Maybe to call them social would be an overstatement. But, I mean, is there any signatures such that species that do have more complex social relationships show more disposition towards innovation or creativity generally?
Danna Staaf 49:22
I think we don't really know yet. The squid that you're thinking about, I'm pretty sure, is the reef squid that have been studied quite a lot to the point that some of the researchers studying them have quite seriously proposed that they have a language that these these scientists have been able to track the patterns that they show on their skin, not for the purpose of camouflage, but for the purpose of communicating to each other. And those patterns are covering things about mating, things about the environment potentially. It's not like they have a dictionary yet, but there's clearly a whole set of behaviors that the squid are using to communicate with each other. And reef squid, in particular, are interesting because they will group in a squad, many of us like to call a group of squid a squad, of different sizes. And most other species of squid will not do that, because the big ones will eat the small ones. And so they will only form squads of exactly the same size squid and so that cannibalism doesn't become an issue, but the reef squid will actually mingle sizes without cannibalism seeming to be a major issue. And so it's definitely like a species, I think that people like to look at as what, you know, we see some things here that look familiar to us. What else could there be? Could there be culture? Could there be language? Could there be all these things?
Marty Martin 50:37
Well, the social influence on cognitive evolution, development, I mean, there's a lot of back to the reproduction side, a lot of the mates sort of, you know, it's a one way street, the male doesn't necessarily make it out of that situation. Right. There's cannibalism there, too.
Danna Staaf 50:51
Yeah, absolutely. Yeah. Which is why a lot of a lot of octopuses have evolved to mate at arm's distance.
Art Woods 50:57
Otherwise, too dangerous
Danna Staaf 50:59
Literally, the male will collect his sperm and pass it down to the very tip of this specialized arm. But then there's there's a couple species of octopuses that have been fairly recently studied to, to meet in a much closer position, beak to beak sort of an intimate mating act and terrifying when you consider that the beak is how they eat each other and very sharp, and will even share dens, which was basically unheard of for octopuses before that. So there's definitely still a lot out there that we're only just beginning to understand.
Art Woods 51:31
Super interesting. So sticking on cognition and intelligence, just for a minute, you know, I think another signature of that kind of thing is tool use. So are there tools that different species use?
Danna Staaf 51:44
Definitely. And I think we're well past the time in history when tool use was thought to be an exclusively human phenomenon. But I think it still excites us quite a lot when we see animals do it and certainly does me. I think it's very cool when you see a crow like picking up a stick to pry something open or dropping a nut, so that a car will drive over. Something like that. And yeah, octopus is definitely do they, they will manipulate objects in their environment to be where they want to be. One of the earliest examples of observing this, I was really excited to learn because it was when I was working on my book, The Lady and the Octopus, which is about Jeanne Villepreux-Power, who invented aquariums in the 1830s, to study octopuses. And she was most interested in the octopuses that make their own shells, the argonauts, which we could get into later if we have time.
Danna Staaf 52:31
But she also studied common octopuses. And she found them taking little rocks and sticking them into the opening of a clam, when it was opening its shell to feed. She saw these octopuses just like they would quickly go, throw it, throw a little rock in to hold the clam open.
Art Woods 52:48
So the clam can't close.
Danna Staaf 52:51
Right and they would wait for the clam to open. They just sit there and wait. And when the clam finally needed to take a breath or to eat and had to crack its shell open a little bit they throw the rock in and then the clam can't close it’s shell all the way so they'd be able to get in there and open it. In more recent times an amazing octopus scientist named Christine Hufford has observed octopuses that, somewhat famous within the world of cephalopods, coconut octopuses carrying around half coconuts as a sort of mobile home, and the walk around with them, and then if they're threatened, or if they need shelter, then they'll drop them and hide inside them and sort of pull the coconut halves over themselves.
Marty Martin 53:30
That's crazy. Okay, so I think we have to extend the question into the potentially uncomfortable mystical kind of space. What's the expert consensus now about consciousness, and cephalopods? I mean, do we know about self awareness? Do we know about dispositions to lie or play? Or, you know, what's there? If you know the Dunbar number in humans? I mean again, it's weird, because that invokes human cognition as this thing about social complexity, so Dunbar might not be the right kind of thing. But yeah, what do we think about consciousness in octopuses?
Danna Staaf 54:06
One of my favorite things about octopuses, cephalopods generally, but I think octopuses tend to pull this out the most, is that you can't stay away from philosophy for long when you're studying them. You know, no matter how you're like, "Oh, we're just gonna, like be very scientific about this, and we're just gonna study their lifespan, or we're gonna study their diet or something." They seem to really bring this out of us, either as scientists or as just observers, or journalists or anybody, these philosophical questions. And I think it's the same thing that grabbed me when I was ten is that there's there's such an embodiment of familiarity and difference. A lot of animals we look at and we're just like, wow, that's super weird. Like a butterfly, a caterpillar that turns into a butterfly. That's super weird, but we don't look at it and be like, "Oh, the caterpillar is looking back at me and like, what if that happened to me?" You know, most of us don't get really deep into the philosophy of that. I do sometimes because I'm a weirdo, but it's not typical. But I think that looking at an octopus, we see that oddness that like its body is so different from ours, the life that it lives and the world that it inhabits is so different. And yet it's, a lot of it's in the eyes, because we're used to looking at other humans in the eye, and the octopus looks back at you. And a lot of it's in the behavior. They do exhibit undeniable curiosity, exploring their environment, not just because there's food somewhere, but to explore it to learn about it. Play, absolutely, play behavior has been documented, and personalities. So different octopuses will reliably behave in different ways, not just the octopuses either, but squid as well.
Danna Staaf 55:44
And if I make a quick detour, I want to mention that I think the reason that although cephalopods generally are cognitively complex we tend to focus on octopuses is that it's just easier to study them. Most squid are really hard to keep in the laboratory, because they have these escape jets, they have these really fast swimming lifestyles. And so you need a massive tank to keep them happy. And then it's really hard to give them the sort of cognitive tests that we're wanting to give an octopus. An octopus, like I was saying, it wanders around, it goes back to its home, you can give it a maze to solve. It's really hard to think of how you would give a squid a maze to solve. So I think that a lot of it's there in squid, but it's just really difficult to study.
Danna Staaf 56:23
But the octopus is we we look at them, they look back at us, we notice their personalities, there's some that will be reliably bold when it comes to facing off against a threat, but shy when it comes to exploring an environment just as an example of like axes of personality that scientists have pulled out. And I think that they come to symbolize that then for people, of nature generally. Like if you look at an octopus, and you can simultaneously say "This is so similar to me that I don't want to eat it," which I hear from a lot of people who are not vegetarians generally, but they'll tell me I stopped eating octopuses after I watched My Octopus Teacher, or after I saw one at the aquarium, or after who knows what. So they'll look at and say, "It's so similar to me, I don't want to eat it. And then at the same time, it's so weird, I can't possibly comprehend what it's like to have eight arms and section cups and camouflage over my whole skin." And then we look at all of nature, I think that can really expand us and be like, but that's the world we live in. We're part of it. It's all related to us. And yet we're kind of stuck being human, and just using our imaginations. I don't know if I even answered your question. But I just love that you asked it because I think it's something that octopuses bring out of us. And that's cool.
Art Woods 57:35
Yeah. I have one follow up about and I don't think it's necessarily about consciousness, but it's about the way octopus nervous systems work. And it's this observation that so much of it is distributed, right? So they have kind of a central nervous system, but then also, you know, nets that go down into their arms. Has anybody any biologists thought about, like, what that means for the way they process information and how they might think and be conscious in such a distributed system?
Danna Staaf 58:01
Totally. Scientists have totally thought about it. And so have science fiction authors, which I love.
Art Woods 58:07
I have a question for you about that, too.
Danna Staaf 58:11
Yeah, Children of Ruin?
Art Woods 58:12
Yes. We'll get there.
Danna Staaf 58:16
Very good. Very good. Yeah. So there's, there's actually like a little sort of factoid that you can also bring out to cocktail parties, if you want, that has come out of that research, which is saying that octopuses have nine brains, which is something that I feel a little so like octopus is definitely have three hearts, and I trot that one out all the time. And then people are like, whoa, that's so crazy. And then I explain that it's actually very similar to the fact that you have one heart with four chambers, just imagine that your chambers were separated. That's what the three hearts of an octopus are. It's just they have one systemic heart for pumping to the body and it just sort of separated that. But I think like, you know what, the nine brain thing, I think it's valuable for getting across a real piece of information that their nervous system is way more distributed than ours, and then discussing it, because it's true that they have a mass, a central nervous system, a brain in this in their head. And it's shaped weird, by the way, it's like a ring, a doughnut around the esophagus, and then these two big optic lobes, and then they also have a mass of nervous tissue in each arm, ganglion. Let's call it a brain. Why not? Because it is clearly not just sort of sending signals to the muscles of the arm, the skin, the suction cups, but it's also integrating information and to a certain extent making decisions. So there is some independent, maybe you could even call it problem solving that's happening in the limbs that doesn't need to go to the brain. And there's even connections between those ganglia in the arms, where they can send signals back and forth to each other that don't have to go to the brain.
Danna Staaf 59:49
So I think we're still very early in understanding what that means, like the ability to scan brains on that level of detail to see where the connections are is new. And so I think over the next few years, decades, we're going to learn a lot more about it. And it's going to be really cool. And yeah, thinking about what does it mean then to be to have that experience? I think it's really hard for us to get away from this thought of like, what is me would be the brain. So I would be the central nervous system. And I would feel like my arms were moving of their own volition. And like, okay, maybe, but like, maybe you is everywhere, too.
Art Woods 1:00:28
Right? So is there experimental evidence that there's like local processing in an arm as if it's thinking unto itself and taking action of its own volition?
Danna Staaf 1:00:38
Yeah, to a certain extent. So there have been some studies where the ability of the central nervous system to perceive the environment is blocked off. Basically, it just you can't see. So like, get their arm through a hole looking for food, and they can't see at all or take any sort of action from what you would think the central nervous system would be. And the arm is able to do a certain amount of like maze solving and finding food and independent reacting even to like a bright light being turned on.
Art Woods 1:01:07
Yeah got it. Ok so we brought it up. So I have read this series now a couple times by Adrian Tchaikovsky starts with Children of Time. The second book is Children of Ruin. And you know, without going on about it at length, I'll just say it's awesome. And book two has space intelligence spacefaring octopuses. So just let that sit in your mind for a minute. And to me what's so interesting about the way Tchaikovsky approaches all this stuff is that he really incorporates a lot of biology of the organisms that are the sort of focal taxon of the book like spiders in the first book and octopuses in the second. And he has this sort of vision of the way these distributed nervous systems are working and how they're communicating using, you know, color patterns on their skins and how bizarre their language and their thoughts must be. Anyway, I just wanted to get your impression of that book. And you know, are you a super fan? And what was your reaction to it?
Danna Staaf 1:02:00
I loved those books. I'm very impressed with Tchaikovsky's work. It is, as you say, like incredibly grounded in science, and I am a sucker for hard science fiction. Pun intended. That includes cephalopods for sure. And absolutely, like one of the highlights so far of my science communication career was being invited to be on a panel with Adrian Tchaikovsky at a British science fiction convention called Eastercon, it was so cool. So I zoomed in, I was a remote participant. He was one of the guests of honor, so it's not like this panel that I also happened to be on was the only thing he was doing. He was like giving a talk and doing all kinds of cool stuff. But I was very excited to to be on it with him. And we talked there a couple of other people there, and we talked about a lot of this stuff about like, what would consciousness look like and other non-human forms, and it was super fun. He's a fantastic nerd and like a very kind person, as far as I can tell. So
Art Woods 1:02:54
Any of the biology objected to in the book, like anything you stumbled over besides spacefaring, I mean?
Danna Staaf 1:03:00
I have a different take on it. I mean, the space is great, it was totally like a plausible presentation of how the octopus has got there. And the great, great backstory of how they got there, how they ended up sort of genetically tweaked to be what they are in that book, I do feel like the way that he presents their awareness, their self awareness is sort of what I was describing at first as their main awareness is central. And from there, their conscious awareness, these, the sentient octopuses in space, their arms are kind of just doing things. Presents them, but he does it in a really compelling way. He presents them as like not, they basically are not ever aware of the details of what they're doing. Their conscious awareness is all sort of big picture, managerial almost. And then their arms just carry things out. They do mathematical calculations, but they couldn't really talk to you about the mathematical calculations they're doing. It just happens on the level. It's so cool.
Danna Staaf 1:04:03
So like, I don't argue with that. I do think that if I were to write such a thing, like, first of all, I would need some skills that I'm still developing, to put it gently. But also, I think I would prefer to explore like, what would it mean to actually be consciously aware of all of your body, to feel that you were embodied and that the decisions were more distributed? I think that would be interesting, too. But I love the way that he does it.
Danna Staaf 1:04:29
And one of my favorite things is about his communication between the humans and the octopuses as they're trying to, like build this rapport, is that the way the octopuses communicate with each other is of course through their skin patterns, which is like obviously the correct thing to do. If you have sentient octopuses, and so they flesh colors and patterns on their skin. And because they're pretty technologically advanced, that has become a language that they can also transmit electronically, colors and patterns on screens to each other, to communicate with each other. And the humans. There's one human in particular, she's trying really hard to decipher it and like break through. And she's got her own screen. And she's trying to put the right colors and patterns on it to communicate with these octopuses. And of course, there's all kinds of lives at stake. And it's very important, and they're kind of not paying attention to her. And so she's like, do I have I not understood the language, what's going on with me, and she finally gets really frustrated, and gets super emotional. And just like, over the top, like, "I am so upset that I can't make myself understood that I had so want to make myself understood," like very dramatic. And that finally makes the octopus pay attention. As basically they just thought she was boring before.
Art Woods 1:05:35
They need this sort of emotional current in whatever they're saying. Yeah, yeah,
Danna Staaf 1:05:39
They are very volatile creatures, and they can't understand you unless you are also like, what humans would consider to be over the top emotional, which is really it's sort of I love that it sort of plays with this idea that for humans, when we're communicating with each other, we're often like, "Okay, can you calm down? I can't understand you, please, please, like be a little more logical." And these guys are the total opposite. If it's just logic, we don't care.
Marty Martin 1:06:04
That's really cool. This is the second time that this series of books has come up on the show. So I'm still yet to read this thing. I really need to read this and I'm a big sci-fi fan two's. I've got no excuse. I think it would be inappropriate to let you go without giving you the chance to talk about if you have one, your favorite. Is it the vampire squid, the giant squid, which we've not even mentioned the Argonaut that you briefly alluded to, or something else?
Danna Staaf 1:06:31
It's like, I have two children. Would you ask me which is my favorite?
Marty Martin 1:06:37
I know that’s a terrible question isn't it?
Danna Staaf 1:06:38
No, no but they don't care. I mean, the children care but the cephalopods don't care. The argonaut is definitely one of my favorites, because it is an octopus. So it's part of this group that completely evolved away from shells like their ancestors had small internal shells. The modern ones have no shell at all, no hard parts except for a beak. And then over time, these argonauts evolved a totally new way of making a shell. It's completely different from the way nautilus makes shells, from how the ancestral cephalopods made shells. Their arms secrete it's calcium carbonate, but it's a different sort. And it's a different matrix. And the shells themselves are much thinner, they're translucent, which is why sometimes argonauts are called paper nautiluses because they make these very thin, translucent shells. And It's different. They don't they're not born with it, they start making it after they hatch, and only the females do it, because it isn't for protection so much as it's for their eggs. And they spend their whole lives building it up. And then they lay their eggs in it. And they use it as like an egg case.
Danna Staaf 1:07:45
And they're just everything about argonauts is cool. And the whole story-this woman, Jeanne Villepreux-Power, who I mentioned, who invented the modern aquarium, because she was trying to figure out how they make their shells. And she was able to do that in the 1830s. And so it's tied in with the history of women in science and this woman who had to be super determined to like be an inventor and be a scientist and then like really speak up for herself because most of the scientific societies at the time didn't even accept women. So the whole story like researching her life and researching the argonauts has a very special place in my heart.
Danna Staaf 1:08:17
Oh, and then the male Argonauts are really tiny and nobody found them for a very long time. So I mentioned that a lot of octopuses mate at a distance, they have a specialized arm for passing sperm. So argonaut males, this specialized arm is like three times their body length. It's like they have this tiny, tiny little body and then this giant arm and then loaded up with sperm and it breaks off. And then it sort of wiggles around in the female's shell until she's ready to use the sperm to fertilize her eggs. And so that arm Jeanne found it, other people found it and they thought it was a parasitic worm. Jeanne was actually the first one to look more closely at it and be like this has suction cups in kind of looks like an octopus arms, so maybe this is actually the male. But even she couldn't find the rest of the male. It took a while for them to figure that out. Argonauts are bizarre
Art Woods 1:09:04
Super cool. Super cool. All right Danna. Well, we've covered just a ton of interesting topics. Thanks so much for talking to us on Big Biology. It was a really, really fun conversation.
Marty Martin 1:09:12
Thank you. This was great.
Danna Staaf 1:09:14
Thank you so much.
Marty Martin 1:09:24
Thanks for listening. If you like what you hear, let us know via X Facebook, Instagram or leave a review wherever you get your podcast and if you don't, we'd love to know that too. Write to us at info at big biology.org
Art Woods 1:09:34
Thanks to Steve Lane who manages the website and Molly Magid for producing the episode.
Marty Martin 1:09:39
Thank you to Dayna De La Cruz for her amazing social media work and Katie Shahmehri produces our awesome cover art.
Art Woods 1:09:44
Thanks also to the College of Public Health at the University of South Florida and the National Science Foundation for support.
Marty Martin 1:09:49
Music on the episode is from Poddington Bear and Tieren Costello.