In Our Time - Cephalopods

Episode Date: February 1, 2018

The octopus, the squid, the nautilus and the cuttlefish are some of the most extraordinary creatures on this planet, intelligent and yet apparently unlike other life forms. They are cephalopods and are part of the mollusc family like snails and clams, and they have some characteristics in common with those. What sets them apart is the way members of their group can change colour, camouflage themselves, recognise people, solve problems, squirt ink, power themselves with jet propulsion and survive both on land, briefly, and in the deepest, coldest oceans. And, without bones or shells, they grow so rapidly they can outstrip their rivals when habitats change, making them the great survivors and adaptors of the animal world.WithLouise Allcock Lecturer in Zoology at the National University of Ireland, GalwayPaul Rodhouse Emeritus Fellow of the British Antarctic SurveyandJonathan Ablett Senior Curator of Molluscs at the Natural History MuseumProducer: Simon Tillotson.

This is the BBC. Thanks for downloading this episode of In Our Time. There's a reading list to go with it on our website, and you can get news about our programs if you follow us on Twitter at BBC In Our Time. I hope you enjoy the programs. Hello, the octopus, the squid, the nautilus and the cuttlefish are some of the most extraordinary creatures on this planet, intelligent and yet so unlike other life forms.

They are cutler pods and are part of the mollusk family like snails and clams, and they have some characteristics in common with those. What sets them apart is the way members of their group can change colour, camouflage themselves, recognise people, solve problems, squirt ink, power themselves with jet propulsion and survive, both on land briefly and in the deepest, coldest oceans. And without bones or shells, they grow so rapidly, they can outstrip their rivals when habitats change, making them the great survivors and adapters of the animal world.

With me to discuss a couple of odds are Louise Olcock, lecturer in zoology at the National University of Ireland, Galway, Paul Rudhouse, Emeritus Fellow of the British Antarctic Survey, and Jonathan Ablett, senior curator of Mullocks at the Natural History Museum. Lee Alcock, I'm outlined them very generally, but can you give us more detail of the range of cephalopods and where they are found in the oceans? So the main groups of cephalopods that people would be familiar with,

octopuses, squids and cuttlefishes. But there's also nautiluses that have the shell that we find in the Indo-Pacific, and there are more obscure groups like the vampire squid that we find in the deep sea. And you find geppropods everywhere, really. They are in the intertidal, they are in the subtidal, just below our shore level. They are in the deepest oceans. We haven't actually found them in the Hidal trenches. So if you went to the Marianas Trench, we don't know that they're there,

but we've hardly looked there. So there's probably a good chance they are. But they're on the sea floor. They're in the water column. Of course, different cephalopods are in different places. So octopuses tend to be on the seafloor, although there are pelagic octopuses as well. And you find squids up in the water column. And you find cuttlefishes in coastal areas on reefs.

So different groups of cephalopods are in different places. But overall, anywhere you look in the ocean, you'll probably find a kephopod. Are the clusters in particular places? The octopuses have preferred regions and so on? They do. Well, they're always on the same. sea floor or the certain type of octopus are always on the sea floor and they tend to be there are a lot of them in coastal regions a lot of them in the tropics but they get to all areas because they are both poles as well

they're in the arctic and they're very very diverse and abundant in the antarctic as well they don't tend to cluster in large groups of organisms because octopuses actually tend to be territorial and solitary so you won't go somewhere and find a whole host of octopuses but everywhere you go you'll probably find them except perhaps on the deepest seafloor. The abyssal plains, octopuses are not really known from. In fact, we didn't think they were on the abyssal plains at all until a couple of years ago when an ROV team actually found one at about 4,000 metres.

And that's an indication that we haven't explored the whole ocean yet, and there may actually be cephalopods where we don't expect them. Can you give us some idea of the range of their habitats and how we know that? We know where a lot of them are from fisheries. So if you trawl on the seafloor, you will bring up octopuses and squids. Squids that live just above the seafloor. So squids live in differing habitats depending on which group of squids they're in. So you'll find some just above the deep seafloor.

And in fact, they will migrate at night. So you can catch those with a bottom trawl in the day, and you can catch them by jigging and with pelagic nets at night time. but you also find squids right in the wide open ocean so we've collected them from nets there and so a lot of our knowledge comes from fisheries but in the last few decades with the development of technology we've had ROVs in different places in the ocean

remotely operated vehicles so these are submarines that are connected to the mothership by a fibre optic cable so there's not actually anybody in the submarine but it's got cameras that are being operated from the surface and we can deploy these now to almost any depths and we're seeing parts of the ocean that we've never seen before and we're finding cephalopods everywhere.

Is it surprising the range of their habits? I think there are not many organisms that get everywhere. Fish are one of the creatures that gets everywhere, but apart from fish, cephalopods are perhaps unrivaled in where they get to and it's probably because they are so flexible in their body shape and their lifestyle they've really diversified hugely into different forms and they've found unique ways of dealing with buoyancy

and that's allowed them to be both on the seafloor and in the water column and so they've been able to get to places which many animals haven't Paul Wrighthouse would the fossil records tell us well the the cathopods go right back to the beginning of the paleozoic era the Cambrian period. That's about...

About 600 million years ago, that starts. And they first appear in the fossil record as developments from the primitive mollusk, which would have had a conical shell, and the first Keflopod started to grow septi or chambers in these shells, which could be gas-filled. And as they evolved,

they grew a tube that connected the chambers through which ran a thread of living tissue and that enabled them to pump water and gas in and out of the chambers and so adjust the buoyancy. So right back in the beginning of the Cambrian that evolutionary process started. So we can see you can track the evolution through from the fossil records. Absolutely right from that period which was when complex life really first appeared and started to diversify, the kephalpods were there right at the outset. And they diversified through the Paleozoic, and mostly with external shells, but by the time we got to the end of the Paleozoic, there were forms appearing that had internalized the

shell, and the shell had started to become reduced. And those are what led to the colloid kephalopods, the squids, octopus and cuttlefish that Louise has just talked about. But then at the end of the Paleozoic, has we moved into the... Can you just keep giving the listeners the odd date? Yes. They might not have a million years ago.

Yeah. There was a major extinction event worldwide, about 60% of life forms were wiped out at that time. Do we know why? Well, it was a period when the Earth, planet Earth, was at a, at a more primitive state that it is now. There was a lot more volcanic activity,

and it's thought that there was a major period of extra volcanic activity that would have caused changes in the atmosphere and changes in climate, and that led to this major extinction about 250 million years ago. But critically, many of the shelled Keflopods died out at that time, but a few made it through, and also these early forms that had internalised or lost the shell also made it through.

Was that because of the way they were, it must have been? So can you just tell us the chastristics that enabled them to see it through, not only this extinction event, but others that followed? Yes, yes. It's hard to say precisely why, but clearly there would have been so, it would have been dramatic changes in the environment

and so species that have become that evolved and specialized for particular environments at that time that that environment might have changed so radically that they would have simply not been able to survive some possibly less specialized forms will have made it through and so we see as we come into the mezzoic at the triassic Jurassic period which was the age of the dinosaurs we have had a few shelled cathopods and a few of the non-shelled cathopods made it through. And then there was a major radiation, and the shell cathlopods evolved into the ammonites and bellamites and nautiluses that we see in the fossil record and in the cliffs at Lyme Regis, the fossil record in that part of the world.

then there was another at the end of the at the end of the mesozoic period 65 million years ago there was another major extinction this time possibly due to a meteorite a large meteorite hitting the earth and this is when the dinosaurs went extinct and again there was a major extinction something like 30 or 40 percent of all life forms disappeared many of the shell kephalopods disappeared the ammonites went completely, but critically, the non-shell types that made it through, and one-shell type,

the Nautilus that Louise has already talked about, made it through into the tertiary period, and from then on, we've seen evolution towards the fauna that we have today. Thank you very much. John Abblett, and their mollusks, what do they have in common with other mollusks? So, I mean, they're very diverse group of animals, the mollusks. We have, of course, the slugs and snails, the squid in the octopus, the kevlopods, and sea slugs and sea snails. But there are features that link your snail and your squid. So some of those are the kind of nervous system, although it has varied throughout. They have a very similar nervous pathway.

They have bilaterally symmetrical, so they kind of, if you fold them half, they look vaguely similar. They have a mantle. So this is an area of tissue that surrounds the visceral mass that surrounds the digestive and reproductive systems. and it's often modified for breathing, so for a lung in terrestrial and as gills in aquatic species. They have all except the bivalves, there's always an exception to the rule, so bivalves, things like clams, mussels and oysters,

but all the other groups have a structure called a radula. This is kind of the rasping tongue. So if you see a snail eating your lettuces or your flowers, that kind of rasping action, the pulling off of that vegetation, there's a very similar structure, the same, called the same thing, a radula. In keflopods, they're not. eating your plants. They're predatory, but they're also breaking down the food. They're rolling

this tissue over, and that's also how they're feeding. And of course, the other structure is, as has been mentioned, the shell. So it's very obvious a shell in a snail or a sea snail. And as it's already been said, the Nautilus is the only species currently that has an external shell, whereas in cuttlefish, they have the internal cuttlebone. In squid, we have the internal pen or gladius. And in the octopus, where there's two main groups, one has completely lost the shell, but their ancestors had it, and in another group, they have a very small sort of vestigial shell.

So there are similarities between all these very diverse groups. Before we knew what we know, the Kevlarpods, what were the myths and stories that grew around them? So this is something I really like. So lots of cultures around the world

have these kind of giant, squared, giant octopus legends. You get them all across Southeast Asia. You have the Lusca in Caribbean mythology. You have the Skylar in the Odyssey, in Greek mythology, you have the Krakken in northern Europe, these kind of sea angels. And these are all octopus-y-like tentacled sea monsters. So I think all cultures share this kind of fascination with these huge unknown beasts. And I think the reason is that octopus and squiridivs,

they are unusual. They're very different to the life forms that we generally see in the water and on the land. They're very alien to us. I think aliens are good word when you think of describing them. So if you imagine you were a sailor or someone who worked around the coast and you were coming to contact with something, or maybe a bit of a squid washed up on the beach, it's very easy to imagine that these were parts of some gigantic, terrible beast. And even in modern culture, in 2016, the film Arrival that came out, which was about an alien species landing on Earth.

And the form that the film took for the aliens was of a kind of very Keflopodi-type creature. They had seven arms. They squirted ink to communicate. So still today, we're still seeing these creatures as alien-like and fascinating. Then when you do the arts, in the Minoan art, as I understand it, can you tell us how they figured that, Louise? Yes, I was at Canossus not long ago, and the Minoan art has a very stylized octopus with bulbous eyes and very long arms that they twist around the jars. It's very, very common to find them on jars and pots in Minoan pottery.

Let's get down to the detail of octopus. Which of them change colour and how do they do it? And perhaps why do they do it? Okay, most of them can change colour and they do it in different ways depending on what sort of kaffirpid they are and where they live. So if we think first about octopuses and cuttlefishes,

they tend to live on reefs where they have a distinctly coloured background which they would like to camouflage themselves against. And they are masters of camouflage. They do this using particular organs and cells in their body. So they have these things called chromatophores, which are basically little coloured cells in their skin surrounded by a ring of muscle.

And in the relaxed state, the muscle closes over the little coloured cell. And when the muscles are contracted, they pull back and the coloured cell is exposed. But what's interesting about these is that the colours in these cells, are only three colors really. They're yellow, red or brown. And that doesn't mix with what we know about the colors that octopuses and cuttlefishes can show off. So they have other, they have other structures deeper in the skin than this. Firstly, they have eridophores. And these reflect light. And they've got this interesting protein in them called Reflectin. And Reflectin is a sort of

self-organizing molecule. It stacks itself in layers. But depending on how closely packed those layers are, it reflects a different wavelength of light. Now what the octopuses can do is they can release a neurotransmitter, acetylcholine, and that causes phosphorylation of these little molecules, the reflecting molecules, and that affects how closely packed they are, so it affects what colour they are reflecting back. So they firstly have these chromatophores that show some basic colours, and then they have these eridophores that they can alter the colour that they're reflecting. And below that, they have lucaphores, which just reflect back any colour that is coming on to them, which obviously in certain respects you wish to reflect back

the light of your environment. And at the same time as all this, they can actually shape the pili on their body so they can make their skin go all bumpy. So if they're on a rocky surface, they can make themselves look much more like a rock and completely blend in. And the beauty of this colour change is because it's all innovated by nerves, it can happen really, really fast. So they can do it in about 200 milliseconds, they can completely change colour. And is this for predatory purposes? This is mostly for camouflage. Yeah.

They use it for other... So not as much eating as being eaten? Yes, to prevent being eaten. Who are the biggest eaters? Other fish would... You've got to be a pretty big fish to swallow an octopus, I assume. So we're talking about whales, are you? Whales would take squid.

They wouldn't be taking octopuses, and you wouldn't have whales that close in on the reef. Sorry? Rather discerning well. Yes. But they also do colour change for mating purposes, so they signal, particularly cuttlefishes. Can we develop this form, this changing colour? Yes, a lot of it, a lot of the interests around this is in the eyes of the Keflopods.

The eyes are enormous. Can you tell them this as the enormous? Yes, well, the largest eye of any animal is a giant squid, but all the colloid cephalopods have a very sophisticated eye which is very similar in function to the vertebrate eye but it's actually a spectacular example of convergent evolution where very different structures have evolved to do the same thing and so the eyes of the cephalopod are they have a pupil but it's not round It's square and if they need to reduce the amount of light going in they make it into a small rectangle They have a lens, but again it's different from the lens of a

vertebrate eye in that it Focuses the image onto the retina by moving the lens back and forwards rather as we do with a in a camera rather than the vertebrate eye as we have where the lens changes shape to focus and they they have a retina with very different cells that that can have high visual acuity, but most of the keflopods that have been looked at are actually colourblind. And this is really why I... This is the interest in relation to these fantastic colour changes

that the kerfla pods can do with their skin. They can't see those colours. They can see light and dark and they can also see polarised light. So where the oridophores that the bees referred to in the cuttlefish are used for patterning and changing patterns and communicating with other cuttlefish. And those oridopause reflect polarised light. And so the other keflopods, the other cuttlefish can see those changes, but they're invisible to the fish which can't see polarised light.

so they can signal to each other without giving the game away to the fish. There are one or two squids, there's one species of squid that does see colour, and that's a species which, again, it has light organs, a vast number of light organs on its skin, and it flashes these and uses them to communicate. And that species can see, we think, it can see three colours. in a way that the others can't. John, how do they show they're aggressive?

What signs do they have that can tell us they're going to be aggressive? Well, I guess the warning coloration they show, so as we've said, they can change color in order to communicate. And often we see bright red flashes associated with aggression. If I think about aggressive species of squid, I think of the Humboldt squid, Dostodis, Gygus. are predatory squid. They live on the eastern Pacific from California down to Chile. And these living in quite large numbers, they're quite unusual in the size of groups they live in. And they

attack in a coordinated manner. And they have been known to attack fishermen and divers as well, and actually been responsible for some fatalities. Why would they do that? Have you nailed a reason why they attack certain divers? Well, they're not known to be aggressive all the time. It's thought that they get into a kind of feeding frenzy and if a human gets in the way when they're in these kind of huge feeding clusters then they just kind of don't stop and they get attacked this way

but I don't always think of Keflopods of being aggressive, you know, you might think of the myths and legends of them dragging down boats, but there's some, you know, they're obviously predatory animals so they need to be aggressive but they also need to defend themselves,

as we were saying. The octopus, for example, are venomous, all species of octopus that we know of are venomous. They have venom in their salivism, in their saliva. And when they bite their prey, it injects this venom into them. And this venom often helps to sort of paralyze the prey and also to break down the tissue around it to make it easier to digest. And if you think of something like the blue ringed octopus, this is the most venomous species of octopus. And the cocktail of toxins in the saliva is so great that if they

bit a human, they will actually die. There's been three recorded fatalities and possibly many more and lots of near misses. And this is because the toxin affects the voluntary muscles, so it stops you from being able to breathe, and unless you're given assistance to breathe, then you will die. And of course, that is not just aggressive, but it's defending against aggression from predators. But I actually think that some of the more interesting behaviours are, as we touched on earlier, these courtship rituals, you know, these flashes of light, the way that these animals make. And things like parental care as well. Many octopus look after their eggs. They stop feeding. They kind of keep them safe. They waft them to keep them oxygenation,

and look after them. So although they are seen to be aggressive in sometimes, they, of course, exhibit a whole wide range of behaviours. Louise, how do one of the notable things then move very quickly? How do they do it? And what advantage is it? Well, let's talk about how they do it first. So they move in different ways that the thing that they're famous for is jet propulsion.

And we would have seen that in fossil cephalopods, in ammonites and in early nautaloids. and they have a they have a those groups have a rudimentary funnel and the colloid squids, octopuses and cuttlefishes that we have today have developed this further and as part of their mantle

the mantle is open at the neck of the octopus and the only other opening from it is this funnel so what they can do is they can squish the muscles of their mantle to suck water inside the mantle sack over the organs and then they can strict those muscles around the neck so that the water can't come out of the collar of the mantle and then they squeeze all the rest of their muscles

and squirt that water out through the funnel and that makes them jet propelled and the beauty of the funnel is that it can point it in any direction so they can jet propel forward and they can jet propel backwards as well but it's not very efficient because the funnel's quite narrow and squirting a big volume of water through a narrow tube is not energetically efficient it makes them very fast and it's great for being predatory or for escape but it's not very efficient so they swim in in other ways as well.

They can undulate their fins. And those species which have long fins can send a wave of undulations along their fins. And if they reverse the direction of that wave, the squid will go in the other direction. Or they can send a wave down one side one way and a wave down the other side the other way. And the squid will turn around just like if you reversed one motor on a twin motored boat. But they move in other ways as well because, of course, octopus is live on the sea floor. So they just crawl. And their arms are fantastically maneuverable.

arms are like our tongues because most of our muscles attached to bone somewhere to pull on. But if you think of our tongue, if you wiggle your tongue, it's a free moving muscle and that's what octopus arms are like. So they crawl around using their arms. And their arms are actually amazing as well because they've got mechanoreceptors so they feel with their arms and they've got taste receptors so they taste with their suckers on their arms. So they have all sorts of ways of moving which are exploring their environment at the same time. Paul, Paul Rodehouse, how methodical is the study of these creatures at the moment? Well, a lot of the problems with studying kephalopods

has been the fact that they are soft-bodied. They have very few what we call taxonomic characters, characters that we can use to define a particular species and at other taxonomic levels, family and genus levels. So going right back to Aristotle in his history of animals, there are descriptions of cuttlefish and octopus and squid, which were all found in the Mediterranean and Aristotle had access to. And he made a very good job of defining the main groups and describing them and discriminating between some of the species of octopus. Then we have to fast forward 2,000 years to the 18th century and Linnaeus and the Age of Enlightenment. And Linnaeus started this process of binomial classification of animals,

so where each animal has two names. So the common squid would be Lolligo Volgaris, the common squid. But that was followed by a period of a lot of other people doing, the same sort of thing, but with these very poor taxonomic characters, it created more confusion than it sold. And then by the mid-20th century, we had a couple actually, Gil and Nancy Voss, two Americans, who between them really took a very systematic approach, looking at the taxonomic characters that were being used, deciding which were useful, and really sorting out the really sorting out the problem.

As we move into the 21st century, we've now got the technology, the gene sequencing technology that arose in the Human Genome Project. And so now there's another, a whole new way of classifying and identifying and determining the relationship

between Keflopods. And that is really opening up a whole new area. Thank you very much. John Abbott. What specimens have made their way to you recently at the Natural History Museum? What have you learned from them? So we have about 80 million objects in the Natural History Museum. Of those, we think about 8 million are mollusks,

and of those between a quarter of a million to half a million are the Kevlopods. And we're getting specimens in all the time. I mean, we're saying that the collection started in the mid-1700s, but every week we get new specimens added to the collection. When I think about recent things that have been added to the collection, I guess a personal favourite for me would be a giant squid specimen. So in not very recent, but in 2004, some fishermen from the Falkan Islands caught a specimen of giant squid. They donated it to the fisheries.

I mean, how big, why does it earn its keep as a giant? So giant squid, we think, get to about 13 metres total length. And there's probably one squid bigger, the colossal squid, but we haven't found a fully grown member of that species yet. although when we find the kind of juvenile members of that, they get to, well, I think about nine metres was found in 2008. And so we think the adults get much bigger. But 13 metres is still pretty big to class as a giant squid. The specimen was donated to the Balkan Islands fisheries,

and then it was sent to the museum to me in London. It was 8.62 metres inland, so not quite fully grown, but a pretty good-sized squid. And it's still the largest, what we call wet-preserved specimen. so a specimen preserved in alcohol that the museum has ever done. And, I mean, animals like this are amazing for the kind of public interest of science. When you've got a huge specimen like that, you can talk to people just about how amazing it is. You can talk about evolution.

You can talk about adaptation to environment. You can talk about things like the chromatophores, the behaviour, and just how much we don't know about these creatures. But actually one study, which I think you were involved with Louise, was using this to try and suggest how many species of animals. giant squid are. In the past, it was thought that there were many different species of giant squid. They live in all the world's oceans apart from the polar regions and around the equator. So it would be obvious to think that there is a European species, a South African species, an Asian species,

but actually using this specimen of giant squid, taking DNA and comparing it to other freshly caught and well-preserved specimens around the world, it actually suggested there's only one species of giant squid worldwide, which wasn't what we expected at all. And it's not just the new donations that are fascinate me I sometimes get very excited about the older things that we find in the collection we have a nautilus specimen that was the property of Richard Owen

who is the first director of the natural history museum and he wrote an early work on the nautilus and actually a lot of the time on my desk we have an octopus collected by Charles Darwin well Louise what about the nervous system and that makes them so and what about their intelligence we read all about how very intelligent they are

how smart they are can you just give us some evidence for that. Yes, well their intelligence is connected with the development of the nervous system. It is, as Jonathan said earlier, on a molluscan plan. But what has happened in octopus and squid is that

the various nerve ganglins have come much closer together and concentrated in a brain, which is unusual in a mollusk. And it was very important that they come closer together because octopus neural do not have a myelin sheath like ours.

Our neurons are enclosed by fatty acid called myelin, which helps the speed of transmission. So the speed of transmission down an octopus neuron is quite slow. So if they were all spread out, the transmission would be slow, and the various neurons talking to each other would be slow, and octopuses wouldn't be able to be as smart as they are. So this coming together of all the neurons in the brain

has really aided this. So can you give us some examples of how smart there? And when you've learned about them being able to open jam jars, yes. What else? So they're very good at finding their way. So if you think an octopus mostly lives in a den and it goes out hunting and they can explore their area hunting for a long time and then they can find their way straight back in a bee line.

And we don't really know how they do this. But somehow they're mapping the way they're going. They can also learn through mazes. and it's quite interesting. Octopuses who have a den and always return to it are better in mazes than cuttlefish who don't have a den and don't have to be able to find their way home. So there's clearly learning capabilities

that go with their natural behaviour. Anything else? I think on their intelligence, not so much on their intelligence, but on their nervous system, rather. One of the reasons that they're so adaptable to all their environment is because of their senses. have senses, really remarkable senses. They've got taste sensors in their suckers, but they've even

got light detectors in their arms. They've got op-in molecules in their arms, which are detecting the light. And this is feeding back to their neural system again, which is helping them with their camouflage. So their developed nervous system isn't just about how clever they are, but it's about how they behave and react to the rest of their environment as well. Paul, what do you know about the life cycle? The life cycle of the colloids is one of live fast and die, basically. Nearly all the temperate species that we know about have a one-year life cycle. Some of the small tropical species have a shorter life cycle,

they may be a few months, and some of the bigger species, cold water ones may live for a year or two or two or three years, but they all live for a short period and they all have one spawning event, one reproductive event, and then they die. They have a very high metabolic rate of voracious feeders, they're all predators, they grow fast, they produce in all cases a relatively large number of eggs, and then when they spawn, they often often the squids in particular make quite long migrations, so they use up a lot of energy during the migrations. They then have ritualized courtship and activities. Then they spawn, and then they die. And the body is depleted of nutrients and energy, and they simply keel over after they've

spawned, or probably in most cases they get snapped up by a predator. And that life cycle, is really an adaptation to being able to colonise areas and grow populations quickly when conditions are good. And then when conditions aren't so good, they simply tick over and the populations reduce. But you do get this ecological opportunism. They can move in when the conditions are good. John, can we just talk a little bit more about which has mentioned earlier by Paul about the ability to survive the mass extinctions

and so and so forth? Is there a common factor that says, oh, they survive because of X or X and Y? I think one of the reasons probably they survive these is their intelligence. They are often seen to be this really intelligent creature and most intelligent invertebrate they're often pegged with. I mean, they have about...

What's in charge of it? Invertebrate. So animals without bones. And they have about 500 million neurons in their brain, which is about the same as a dog. And they don't just centralize this nervous system. It's actually a kind of pseudo brain in each of the arms. And this gives them much more adaptability to their environment. So I think adaptation very quickly to an environment is one thing.

And another thing is the short lifespan as well. They're very resilient creatures. Because they live quickly and die, they can adapt very quickly to changes that happens in the environment. Louise, we're told that they can survive out of water but only very briefly. Is there any development there?

Are they just slithering from one rock pool to another and they're caught on the rock instead of in the pool? Well, they're no different from us in that to live they have to breathe. They just breathe a little bit differently from us. and their gills are inside their mantle cavity. So this is the sack that seawater is filtering through all the time. And in fact, they use their musculature to pump seawater

constantly through their mantle sac so that they're getting fresh oxygenated seawater over their gills. So when they crawl out of a rock pool, their mantle sat, they'll probably tighten it a bit around the collar so that it holds that seawater in. And they've got, therefore, oxygenated seawater on their gills until such a time as they've used all that oxygen up out of that seawater. And at that point, they need to reflush their mantle cavity. So they can survive out of water for as long as that oxygen in that seawater lasts. And that's enough time for them to crawl from rock pool to rock pool.

So you're talking about a few minutes? That's right. Maybe slightly more than a few minutes, but probably not more than 10 or 15. And if you, there are some species that live in tide pools, and they tend to hunt at night or in 12. And if you walk along these rocky shores at night or twilight, you will see octopus is walking between tide pools. Not in this country because we don't have these species, but elsewhere in the world, you will see this. Octopus taking a walk.

That's right. Paul, how are they related to fishing stocks? The kephalopods have been exploited by fisheries for millennia, probably going back to the late Minoans. but they have relatively, they've been a relatively low catch, small part of the world catch. But about 20 years ago, a study was done where the 15 statistical areas that the Food and Agriculture Organisation in Rome used to collect data on fisheries demonstrated, a study of these data demonstrated that as the fish stocks have been declining, at worst declining and at best holding their own,

in all of those areas but one, the numbers of geflopods being caught and exploited by the fisheries was going up. And in three particular cases, in the West Africa, off West Africa, in the Adriatic and the Gulf of Thailand, there was a very clear correlation between the decline in the groundfish fishing,

groundfish catches, and the numbers of fish. Keflopods being caught. And this really goes back to what I was saying about them being ecological opportunists. The idea that arose from this is that as you take out the slow-growing big groundfish, these ecological opportunists can come in and fill the vacant niche in the ecosystem. If they were plants, we call them weeds. They're able to grow fast. They don't produce heavy skeleton in the way that weeds don't produce any woody structures and they can move in when the conditions are right and take over.

And this seems to have happened in these fishery areas. And interestingly, only about two years ago, another major study was done by a collaboration of scientists looking at both scientific sampling of kephalopods and fish and also fishery data from new data on fisheries. And both scientific data and fisheries data are showing a continuing trend of increasing kethlopods and decreasing numbers of fish. And this seems to be a function of overfishing and changing the habitat of the conditions

available for Keflopods to move into. So they don't seem to have many threats to them at the moment then, John. There are still threats to keflopods, of course, pollution, like many aquatic animals, will be harmful to them, the change of their environment. So as we damage coral reefs, or as the bottom of the ocean is damaged through trawling, you are of course going to cause an effect on the keflopods. Things like ocean noise pollution are interesting factors as well. So things like drilling, boat sonar, fishing sonar,

these can have an effect on Keflopods and we think that possibly some of the mass strandings we occasionally seen where you get large numbers washing up on beaches could be caused by the effects of this noise on the animals and lab studies have actually shown that when stasis development and this is the organ of balance

that the animal uses to get its pinpoint its 3D point in the environment loud noises actually cause this organ not to develop fully and to develop abnormalities so noise pollution is a problem to them and of course climate change is a big problem. Firstly, if you change the seawater temperatures, you're going to get changes in metabolic activity, so the activity of the squid may change. They may be forced out of areas where

it's too warm or too cold. And also the effect of increasing temperatures means that you change the seawater chemistry. You change the pH of the water. And this can affect the shell development. It can affect the stasis, the organ of balance development. It can change the development of the cuttle bone and the inner sepians of the squid. So really, there are still threats, but they, as we said earlier, they are a very resilient group of animals. They've been around for 600 million years or so.

I think there are some threatened deepwater octopuses as well. They've got very low fecundity, the fined swimming octopuses, and they've been taken by fisheries that are targeted at deep water fish, and they've been taken out at quantities faster than they can replenish themselves. So there are actually some on the IUCN red list

as endangered octopuses. And of course we have the Nautilus, which last year made it onto the CITES list. So these have been collected for the Taurus Valley for their shell. And of course, now they're added to the CITES list. Hopefully it will give them an extra level of protection. Well, thank you all very much. Thank you to John Ablett, Louise Alcock and Paul Rodhaus. Next week we'll be discussing Frederick Douglass,

the great abolitionist, who was born into slavery in Maryland, wrote an extraordinary narrative in his life, negotiated with Lincoln, campaign for African-American rights, and was the most photographed. American in the 19th century. Thank you very much for listening. And the In Our Time podcast gets some extra time now with a few minutes of bonus material from Melvin and his guests. We talked about camouflage in octopus and cuttlefish, but I could say something more about squid, which are a little bit different. Yeah. Because they're out in the open ocean. And so they're not trying to

camouflage against a background of a reef. They're actually trying to camouflage against maybe light coming from above or a darker background below. So they have two things that they can do. They can counter shade their top surface, making it slightly darker, so that for any predator coming from above, they look darker like the seafloor. Or they can counter-illuminate their bottom side, so that for anything coming below, they look more like a moonlit surface. And they do this with photophores.

and so they actually produce their own light and they do this, it's chemical reaction. Some species do their own chemical reaction and other species have symbiotic bacteria that do the chemical reaction for them. So they actually have light emitting photophores and some of these even have a little sort of almost eyelid that they can shut off the photophores

so they can signal with it. But they also have photoreceptors very close to these so that they can detect how bright they're shining so they can moderate how much they're signaling and how bright they are to perfectly match the surface light coming through. So as the sun sets and the moon rises, they can affect how much light they're putting out

with their photovols and become perfectly camouflaged from a predator that's below them. That just kind of shows Keflopods. There's so many amazing things about them. One of the things that really amazes me and we think back to the intelligence is the tool use.

We think of tool use as a symbol of intelligence. think of crows and ravens, you think of dolphins, you think of apes using tools. But when you read that Keflopods use tool as well, I was reading recently about the veined octopus, picking up coconut shells and carrying them around as a kind of mobile defense system. I think that's just fascinating. And there's other species of octopus that gather rocks. Where does he get coconut shells from? So they live, these are a tropical species.

So they, as they wash into the water, they pick them up and they hold them like a kind of a shield to prevent them from being attacked. And another species of octopus that actually makes piles of stones around their dens, there's extra barriers to stop predators from attacking. I just think this is really amazing,

such an amazing group of animals. I've been fascinated by size. Because we have the giant squid, but we also have pygmy squids, which are a thumbnail size. And there's not many animals in the animal kingdom that have such a disparity of size

in their species. And it's not just more and cephrapods that do this, there have been giants through time. There were ammonites that had a diameter of two and a half metres and probably weighed a ton and a half. And there were bellum knights, these early squid that Paul mentioned earlier, that had a mantle of two metres long, which all in all, by the time you had mantle, head, arms, tentacles, that's probably the size of giant squid today.

So we've had these giants through time as well. There are not many animal groups, I think we can say this about. people often ask me what would you like in the museum you know what's your dream one and I have to say I'd like a fully grown colossal squid it'll be a job to preserve it but you know do they get to these 18 metres more the figures that people have quoted throughout the literature

and who knows what size but yeah that was my dream specimen if someone could give me a fully grown colossal squid it'd be a job to preserve but it'll be a fun job do you think I could range that too much well it's an Antarctic species and I normally make myself I'm popular with journalists when, well, I'm talking about giant squid, because although and even colossal squid,

these lengths that people talk about are the total length, including the tentacles. And a squid consists of the main body, which is the mantle, the head and the arms, and then these tentacles that extend out beyond. And the largest body that's been found is about three metres. and if you add the head and the arms onto that, you might add another meter or a meter and a half. And then the rest is tentacle.

So by comparison with some of the big sharks and the big tuners, they're not quite the colossal beasts that people writing about them sometimes crack them up to be. That's not to say, they're not highly impressive animals. and extremely interesting, and it would be fantastic to get hold of some. Thank you all very much. Here's Simon, our producer, coming in to say, tea or coffee.

That was excellent. I'd love a coffee. I'd love a cup of tea, please. In our time with Melvin Bragg is produced by Simon Tillotson. Hi, I'm Rihanna Dillon, and I just wanted to let you know about another podcast that I think you might like. It's called Seriously.

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