Tentacles: The Secret Language of Squid, Octopus & Cuttlefish

Large and flamboyant creatures are cephalopods, a diverse group of animals that includes squid, octopus and cuttlefish. Close relatives of primitive invertebrates such as snails, cephalopods are far more than just simple slugs. They have highly developed brains, superb vision and tentacles with powerful suctioning But their most remarkable trait is their ability to communicate. With complex visual signals and posturing, some cephalopods appear to speak to each other. Each summer, a dedicated group of scientists converge on Bonaire, a tiny island in the southern Caribbean Sea. Theirs is a revolutionary quest to discover if common reef squid are capable of language. In the final, frantic weeks of their short lives, reef squid appear to read and write distinct messages on their shimmering skin. These foot-long mollusks, like humans, are thought to employ a creative, symbolic and visual language. It is difficult to imagine creatures more alien and unlike humans. Cephalopods have blue blood, three hearts and use jet propulsion to navigate through the sea. Theirs is the most advanced nervous system of any invertebrate. They are wily magicians of the deep, the octopuses, cuttlefish and squid. Tentacles are basically arms without bones. These dexterous limbs are utilized for mobility, exploration or capturing prey. The rest of a cephalopod's body is made up of a muscular sack called a mantle, which contains their three hearts, brain and other internal organs. Cephalopod in Latin literally means head-footed. Octopus, squid and cuttlefish belong to the phylum mollusca, a group of soft-bodied animals that includes clams and snails. Unlike many of their simpler relatives, cephalopods have lost their external shells through the millennia of evolution. 400 million years ago, their armored ancestors ruled the seas. These were the ammonites and the oceans once teemed with them. But evolution seems to have passed them by. Only the primitive Nautilus, a living fossil, has retained a protective outer shell. We don't know how ammonites became extinct or why most cephalopods evolved without protective shells. What we do know is that these animals can exhibit an astonishing repertoire of behaviors. They appear to be smart. The evolutionary answer to why octopuses and squid are more intelligent than other invertebrates is probably because while they are derived from molluscs, they have evolved away from using the molluscan shell. A good, big, solid shell is a great place to hide in. And if you're hiding all the time, you don't have to think. As soon as you get out from the shell, you are what some people would describe as bait. Anything can get you. Anything is interested in getting you. And you don't have any built-in protection. Probably not the only way, but an excellent way to get around the problem of not having any protection anymore is to have smarts. The background of these guys is pretty simple. Squid are cephalopods. That means they're molluscs, but they're really unusual molluscs. Dr. Jennifer Mather is a professor of psychology at the University of Lethbridge in Alberta. It's a very short lifespan, so they go from this big hatched to this big doing mating games in less than a year and a half. The crystalline waters of the Dutch Antilles are a long way from the prairies of western Canada. Caribbean reef squid are perplexing subjects considering Mather's primary field of study is human psychology. Her master's thesis dealt with a small species of octopus while her doctorate examined the eye movements of schizophrenics, an unlikely pairing of research topics. Each summer, along with an enthusiastic team of scientists, Dr. Mather travels to Bonaire and its splendid coral reefs. Her ambition is revolutionary. To learn if Sepiotoothus sepioidea, a common species of reef squid, is capable of the most highly evolved of behaviors, language. American Martin Moynihan was the first biologist to present the controversial theory that reef squid might use visual language. But he passed away before proving his theory. Mather's mission, to prove Moynihan right. There's two reasons I chose the Caribbean reef squid for this long-term project. The first one is a really simple one. Martin Moynihan in the early 1980s said that he believed that the squid might make a visual language on their skin. Now this is a really big idea. Humans have language and clearly monkeys have the ability to make a reasonable primitive type of human language. If this were a third language in the animal kingdom, this would be big news. This is a really big question to tackle. Let me see if I can go and crack this particular nut. People often ask me, why are you in a psychology department studying octopuses and squid? Why do you go running off to the reef and watch animals? Does that really have anything to do with humans? And the answer is yes, it does have something to do with humans. The area that I'm really interested in is what has been described as comparative cognition. And that's trying to understand how thinking works by looking at thinking in animals other than humans. Now a lot of people do it by saying, OK, well, we'll look at how monkeys think. What I'm looking at is really something quite different. What I'm saying is, OK, let's take the most intelligent invertebrate, because the octopuses and squid are way ahead of the other invertebrates. They have to have developed intelligence quite differently. In the azure waters of the southern Caribbean Sea lies a tiny island renowned as an environmental success story, Bonaire. This idyllic outpost marine sanctuary is recognized as a world leader in coral reef conservation. The entire undersea ecosystem surrounding the island is protected as a national park of the Netherlands Antilles. Jennifer Mather visited several other Caribbean destinations before choosing Bonaire as a base of operations for her research. The squid are conveniently accessible from shore and are spared the destructive effects of commercial fishing and pollution. When you decide you want to work with an animal in the field, you have to solve a lot of practical problems before you can go work with them. Researchers go to all sorts of strange places to do work, and some of them go half an hour's hike through the bush, and some of them go up to the mountains, and some of them go out in the open ocean in big research vessels. And we wanted something that would be relatively simple. We wanted to be able to go from the shore. We wanted to go to a place where we could find the animals. We wanted to go to a place, too, where animals would be safe. We have to get up early and work hard at a time when people like James are semi-conscious, because that's when the animals are active, and that's what we came to study. I'm a morning person myself, so it's no problem, but some of these others are kind of hard to get up out of bed. I'm basically nocturnal like octopuses are, if left to my own. But in the morning, they are all coming back together and sorting things out again, so we're here. We need to be here. That's when all the activity is. A lot of it, anyway. Mather is joined in the expedition by an eclectic group of researchers. Roland Anderson is the Puget Sound curator of the Seattle Aquarium. Ulrike Griebel is a cognitive and evolutionary researcher from the University of Vienna. She is accompanied by graduate student Ruth Ann Byrne. The final member of the team is James Wood of the National Resource Center for Cephalopods in Galveston, Texas. I'm very fascinated with cephalopods. Well, first of all, they're invertebrates, so they're related to things that don't have brains, and some of them don't even have heads. Yet, they're a group that, behaviorally, is more similar to something like a fish than to a snail. They can change color, shape, and texture better than anything else on the planet. I mean, you might think of a chameleon, but chameleons use hormones, and that has to go through the blood system, and it takes a few seconds. These animals, this is all neurally controlled, so they think it, and they're that. So, they can change what they look like many times in one second. I got involved in the reef squid study here through Dr. Jennifer Mather, who is the team leader of this project. She and I met at a conference back in 1986, and we've been friends and colleagues ever since. A few years ago, she asked me if I'd like to come down here and help her study the reef squid. I jumped at the chance. I'm seeing new stuff every year. I'm coming here now for the fourth year, and I always see new patterns, new combinations of patterns, new behaviors. I think that they need this complex signal language because they are social. As soon as animals are social and live in groups, they need to communicate. This is also the driving force for intelligence, also in mammals. The most intelligent mammals are found among the social mammals, and the same is happening here in the cephalopods. The group's field work is quietly fascinating, but requires patience. Their research demands hours of snorkeling in unobtrusive observation. Individual animals are identified by distinctive scars and skin patterns, and each behavior is recorded for later analysis. Caribbean reef squid are not the species favored by chefs and seafood fans. They are slightly larger and darker in appearance than the restaurant variety. Journalists have branded Mather the Jane Goodall of calamari. We notice personalities in these animals, and we found that there were dramatic differences between individuals such that you could describe them in terms of human personalities or perhaps human temperament. It's almost impossible not to think of them in terms of the human roles. That's why we use this flirting at the bar, that's why we talk about going all the way, making it. From time to time we talk about it as a soap opera because we have all the characters, we have all the situations that you could possibly have in a soap opera. The squid practice a daily routine as timeless as the coral reefs themselves. At night, they disperse to hunt alone. Each day at dawn, small groups of animals gather at precisely the same spot. Early morning is the time for mating games, and this is when things get interesting. They gather together for a few hours of greetings, jousting, courting, and of course, sex. Foreplay may last for hours, but the mating act itself is, suffice to say, quick. Probably the most important behavior that these squid do when they're gathered in these daytime groups is their reproductive behavior. As they come together, females are the first ones to let everybody know they're interested. What we notice is the females rise above the group. They go pale on all of their mantle except just a strip around the front margin, which is kind of a warm brown. When we saw that one, we decided to call it saddle because it looked as if the brown was a saddle around the animal, almost like it was waiting for a rider. When someone is doing something interesting in return, it's probably a male doing stripe. That seems to be the first exchange of visual signals indicating interest in mating in the future. When he's really interested in doing a mating, he'll do a display called a flicker. We call it the flicker because it's on-off, pale dark, pale dark, pale dark. It's so fast that, in fact, we haven't been able to dissect it and find out how often or to find out whether it's all the body at once. But when he does that, it seems to be a fairly honest signal of intent to mate, if she lets him. If a male squid in a school flickers, they have the equivalent of what I say, all hell breaks loose. It's a clear signal that everything's going to happen. Squid are going to zoom all over the school. Other squid are going to come in and try to interfere with it. And if the squid are lucky, they're starting the next generation. The other thing that happens when a male flickers is that it alerts other males to the fact there's an interesting situation coming in here. So they'll do a challenge. They'll do a challenge with the zebra display and coming up beside perhaps in special postures. Often, in order to do anything about having the opportunity to mate, he has to fight off the interfering other males. After four years of study, the scientists have concluded that reef squid exhibit approximately 20 distinctive displays, many of which revolve around reproduction. Each of these displays may involve hundreds of individual components, and there are perhaps thousands of subtle variations. Specialized cells in cephalopod skin called chromatophores contain pigment-filled sacs. Additional layers of cells, iridophores and leucophores, differentially reflect and alter the appearance of incoming light. The three groups of cells work together to form the startling color and pattern changes exhibited by these animals. Next week, I think we're going to have to do an all-day watch on one group and sort of start at dawn and have relays of people coming in, watch for an hour, get out, watch for an hour, get out. Do you think that she didn't want him to mate her? I mean, do you think that's why she was doing the zebra? Yeah, she did the zebra right at him. And she kept the distance, too. I mean, she wasn't with him. Once back at their research headquarters, the team analyzes each morning's observations. I counted 17 today. Individual files cover a wide range of behaviors, including flickers, saddles, and zebra displays. The S.Q.U.I.D. provide the researchers with an endless amount of information and behaviors that must be quantified, sorted, and assigned grades of intensity. Anytime you see that green or blue, the pinkish color, too, that's iridophores. It's a really neat system. The various displays can be sort of quantified and sort of assigned numbers depending on the intensity, whether it was on a quarter of the animal or half the animal or all the animal. For example, the zebra display, the arms can be together, which is kind of a low-intensity thing where they can be completely spread out, which is more of a high intensity. The zebra display can be on only half the animal. So that can be quantified. We just have an incredible amount of information that we get from these animals. Reef squid are very good at communication. Whatever they're doing is obviously very complex and has a lot of different components. Most observations of the S.Q.U.I.D. are made while snorkeling, which has its limitations. With the luxury of a camera team recording them and their subjects, the researchers had a rare opportunity to view their charges up close. Notice there's a fin-based stripe on the under guy. Both of them have. You can see the internal organs there, too. Now she's doing zebra on the left arm. Can we go back on that a bit? See, look at that lower spread. And the upper spread. It's really interesting during the day how they're often this basic brown color, which really stands out against the white background. But in the early morning and at night, they're often light-colored like this, which is much more camouflaged. Now see, when they're maneuvering, they've both got zebra on white, and it's only after they settle for... Photographing the tiny reef squid and their mating behavior proved to be a difficult task. The skittish animals, however, eventually became comfortable, even oblivious to the presence of the divers. Cinematographer Neil McDaniel captured images of behaviors of which little is known. Egg is the final act of a frantic and all-too-short life. When a female's laying eggs, it's really, of course, the culmination of reproduction. And it's a very interesting situation in these animals. Now, biologists talk about this a lot. Who is it who controls who gets their genes in the gene pool? And in the case of the Caribbean reef squid, it looks as if the female has an awful lot of control. Because, of course, when a male does the flicker and he transfers the sperm metaphors to her, it's her choice whether or not to take them and put them inside her mantle cavity. And then, since she's stored the sperm, it's her choice about when to fertilize the eggs with which sperm. Both males and females will die after reproduction, and it's a very short lifespan. We talk about them as having a motto of live fast, die young. An attending male guards the female throughout egg laying. He tries to mate with her right before and even during the process to give his seed an advantage over that of his rivals. After carefully selecting a coral ledge with suitable protection from the elements and predators, the female lays up to 50 strings or fingers of eggs. She squeezes down underneath the rock and she deposits an egg string on the rock. Then she comes back out again. It looks as if she takes a deep breath and goes, that one was hard. And then another five minutes later, on average, she'll do another egg string. They start out life as eggs. There's no parental care whatsoever, and the male contributes nothing except sperm. In only a few short weeks, the eggs hatch and tiny squidlets venture into the water column. From birth, each is prepared to assume the role of marine hunter. Yet, they too must run a gauntlet of predators to reach maturity. In the cold waters of British Columbia, the world's largest octopus appears to have little need for the complex visual signaling used by reef squid. The giant Pacific octopus lives a mostly solitary life, and its reproductive strategy is quite different. Like reef squid, females accept sperm sacs from males to fertilize their eggs. But instead of abandoning her brood, she stays behind to tend the nest in a very motherly fashion. Before she uses the sperm to fertilize her eggs, she seals off a den, produces 57,000 eggs, glues them in strings to the top of her den, and then grooms them for six or six and a half months until they're ready to hatch. During the entire period that the female's there, she does not leave, nor does she feed, and so her body weight will go from something around 15 or 18 kilos down to 5 or 7 kilos when she dies, so she'll lose more than 50% of her body weight. Out of the nest that the female lays, if the population is going to stay stable, all you need is two to survive. They just basically replace the parents. So out of 57,000, which is the average for a female nest, you're only going to get two surviving. More than that, the population increases. Fewer than that, the population decreases, and right now it looks like British Columbia's population is very stable. James Cosgrove of the Royal British Columbia Museum has spent many years studying the reproductive behavior of these intriguing animals. One of the most surprising things I've learned from my research was that the animals are such short-lived animals. It seems unfortunate that evolution would have developed such a magnificent animal, allowed it to grow up to 20 or 30 kilos, only to have it mate, lay its eggs, and die in a period of less than four years. The Gulf Coast of Texas, the research vessel Marine Hall departs from Galveston Bay. Researcher John Forsythe is fishing for food for his captive cephalopods. Hall is used to capture live shrimp, crabs, and fish. Small bay squid are also taken as a bycatch. They are transferred to a holding tank for the trip back to shore. Squid, octopuses, and cuttlefish dislike processed or dead food. They prefer to stalk and capture their prey, much as they do in the wild. Most cephalopods do very well in captivity, and these European cuttlefish exhibit many visual signals similar to those of Caribbean reef squid. In captive environments, they display all the behaviors of wild animals, including mating and egg laying. At the National Resource Center for Cephalopods in Galveston, squids, octopuses, and cuttlefish are raised in a closed seawater system. Eggs, darkly pigmented with melanin, are collected and transferred to special tanks. Each marble-sized egg contains a single animal that hatches in only a few short weeks. These tiny cuttlefish are perfect replicas of their parents. The cephalopods are primarily utilized as marine lab rats and shipped to researchers across North America. Like their rodent counterparts, these cuttlefish provide scientists with valuable insights into human physiology. The reason cephalopods are so interesting is that much of the research we're helping to support is really ultimately aimed at understanding human diseases. But scientists find that going to a human or even a vertebrate is very difficult because the systems are so small and so sophisticated, it's a hard place to begin. So you move down the animal kingdom until you can find a sufficiently sophisticated system that you can begin to understand and ask good questions. And cephalopods, we find, are an interesting place to stop because they have very large elements of their physiology, be it the nervous system or the circulatory system or their brain or their eyes. The processes that are discovered there seem applicable to much more sophisticated systems like vertebrates, even all the way up to humans. This is the premier model in understanding how a living nerve cell can transmit an electric signal down its length. And when you consider that we don't have copper wire inside of us, it really is a miracle that electrical signals can move down living tissues. Back from his field work in Bonaire, Dr. James Wood updates the website that he developed to share cephalopod research. His office is crammed with toy octopuses and squids, a testament to his fascination with these animals. A skilled photographer, he carefully examines his underwater images for new clues to the visual language of the leaf squid. It's clear that cephalopods have varying degrees of visual communication. The intensely social leaf squid are the most expressive, while more solitary animals such as octopus seem to have less need for communication. The complexity of the squid visual displays studied by Jennifer Mather are indeed remarkable. But do they represent a language? Are these squid really able to talk? John Forsythe and James Cosgrove offer differing perspectives on the intelligence and communication skills of cephalopods. There's no question that they're dazzling animals with a broad range of behaviors. To say an animal is intelligent, the best sort of definition or handle I've been able to put on it is to imagine that when an animal is born, you're born with a floppy disk that has so much code written on it, and that code is your behavior or your response to the world around you. I think the question of intelligence will be answered in cephalopods when we can show that the cephalopod can take that floppy disk of behavioral or life options and begin writing new code that wasn't there the day they hatched out. In other words, synthesizing new information into new responses that it didn't possess on the day it hatched. And that, to me, is the beginning of saying, yes, these animals are intelligent. There's no question that these animals are communicating with one another, primarily through visual signaling in their skin, but also their body posturing and their body movements. Reproduction, of course, is a very important area to be able to communicate in for any animal. Squids just don't randomly run into each other and mate and then move on. All the hundreds of hours I've been able to spend watching them, I've never seen a predator get even close to a school of squid. They're gone long before that, so they're extremely effective in that type of communication. To take this to the level of is it a language, is there syntax, or is there sentence structure to the way they communicate, that's very sophisticated and very difficult to get at. I don't think there are many of us ready to just yet say that's the way they structure their communication, but there's no doubt that they do make certain decisions very clearly known to one another. The definition of cephalopod intelligence is a difficult one because we're putting human values on an animal that doesn't live in our environment. When we look at squids and cuttlefishes, we see a lot of visual communication there, and it's very clear that messages are passed back and forth. There is communication happening in that not only is the squid the sender of the message, it's also a receiver of the message, and that's what communication is. It is well known that cephalopods can change color and texture more quickly than any animal. But the theories of the scientists in Bonaire take this behavior many steps further. Jennifer Mather believes the signals between reef squid to be the most complex visual display system among invertebrates. If the signals prove to be encoded with intelligent design, then Jennifer may have discovered something truly remarkable. In terms of do these squid communicate with each other when they're in the groups and they're sending out these displays, this has to be answered by the simple step of saying, what happens afterwards? And I've done some analyses about what happens afterwards, and yes, after these displays, other things happen reliably. So that's the answer of, do they communicate? Yes, they're communicating to each other. Do I always know just exactly what the shades of meaning are? Lots to learn about that. The second part of the question of how are squid communicating is clearly, was my hand right? Do they have a language? And what I have to say at this point is they're so complicated, I can't tell you yet. I'm beginning to gather the basics of the simplest signals. And remember, sexual signals should be simple. I know that in terms of communication, anything that a squid wants to say, it will do not simply, but in a complex way. So there's definitely the background there that they could make a language. It's going to take a long time because it's such a complex thing, because it's such a complex and intelligent animal. There's lots and lots to learn. Four years is just scratching the surface. It may be a few more years before Jennifer Mather can ultimately prove that reef squid are capable of language. There is, however, one thing that is absolutely certain about cephalopods. They generate enormous fascination from a very passionate group of scientists. I think most marine biologists are attracted to something, and sometimes you don't know exactly why, but you're drawn to something. You begin looking at it. And for 25 years, I haven't been able to stop wondering about this animal group. With fishes, I'm not really sure a fish is looking at me. It's hard to tell. But a cuttlefish or an octopus, when you're looking at that in an aquarium, it is looking at you. You're being observed as much as you are observing. There's just new books, new pages, new stones to be turned over that even I can't even imagine right now. But that's what drives a biologist, is knowing that an animal group that you know very well still has those magical mysteries to show to you. I'm crazy about cephalopods because they're smart, and they're different smarts than our smarts, and I'm still trying to understand it. Lots of researchers find that they spend a lifetime with one species because they find that the closer they get to them, the more they get to know them, the more there is to know. And that's the kind of thing I have with these guys. I'm also nuts about squid because they're gorgeous to watch. I love watching the flashes. I love watching the color changes. They're beautiful animals. We don't just do it because it's absorbing and it's fascinating. We also do it because it's great fun. Cephalopods are an amazing group of animals. Species we once considered frightening are proving to be intelligent and wonderfully adapted to their undersea habitat. By evolving with superb communication skills, cephalopods have become less like their simpler cousins and more like fish and perhaps even mammals. What they have accomplished is a remarkable ability to survive, even prosper in a harsh environment. In nature, of course, that's the name of the game.