In the 1960s, Jane Goodall helped change the way we viewed intelligence and sentience in chimpanzees. Her research triggered a core question: if chimpanzees have complex inner lives, what about other animals? Haley Pope explores pioneering research that shows marine organisms also possess and exhibit facets of consciousness, including sentience, self-awareness and intelligence.
The young, blonde Brit had come all the way to Tanzania, notebook and pen in hand, with no concept that she would change the way we understood and studied animal behaviour and cognition; specifically, how we viewed intelligence and sentience in the chimpanzee, our closest living relative. Jane Goodall’s first ground-breaking discovery came in 1960, the same year she arrived in Tanzania to begin her research. While out in the forest one day, she saw a chimpanzee whom she called David Greybeard poking pieces of grass into a termite mound to fish out the insects and eat them. This was the first documented example of genuine tool use in a species other than Homo sapiens. Until then, tool use had been considered a defining characteristic of humankind.
Jane’s findings were published three years later by the National Geographic Society in an article titled ‘My life among wild chimpanzees’, which was accompanied by romantic photos of her in the forest surrounded by chimpanzees. For many of us, the connection Jane shared with them was plain to see. A famous photograph shows her stooping down and extending her right arm to a chimpanzee baby that is mirroring her posture, its fingertips stretched out to touch her hand (see previous spread).
Her research exposed a ‘human’ side of another animal species, one that begged us to reconsider our understanding of animal sentience and intelligence. The scientific community, though, found her discoveries difficult to swallow. Everyone, especially anthropologists, struggled to understand what this knowledge would mean for our species’ identity. When Louis Leakey, Jane’s mentor, received her telegram describing her landmark observation he stated, ‘Now we must redefine “tool”, redefine “man”, or accept chimpanzees as humans.’ Among the many questions triggered by her research, one stood out: if chimpanzees have more complex internal and social lives than previously thought, what about other animals? The floodgate was open.
A decade later, an enthusiastic marine biologist began his scientific career studying bottlenose dolphins off the coast of Hawaii. Louis Herman endeavoured to gain insight into the dolphins’ mental faculties by studying how they communicate. So complex did this field prove to be that he dedicated the next 46 years of his career, and life, to it. What he discovered would also change the course of behavioural and cognitive science. Louis and his colleagues documented dolphins’ abilities to learn and respond to human language transmitted through auditory and visual signals. Not only did they teach two dozen words of an artificial language to a pair of dolphins, but they also realised that the dolphins could understand what individual words meant and how their arrangement affected the meaning of a sentence.
Unlike many animals, which take time to learn what human gestures mean, dolphins were immediately able to understand a signal such as pointing. This hadn’t been observed in other species and it showed, crucially, that dolphins are able to understand a species other than their own. Also unknown until Louis’ research was that dolphins use echolocation to image their environment and detect the distance, shape and size of objects. His pioneering work and discoveries proved that dolphins have complex communication and comprehension skills, which is why they are now considered the cognitive cousins of chimpanzees.
Jane Goodall and Louis Herman helped shape the animal cognition field and ignite scientific interest in the subject. It became clear that, at least for mammals, animal sentience and intelligence are complex and mysterious. Future scientists would branch out to explore the inner lives of countless other animals: elephants, dogs, pigs, ravens, whales, fishes, octopuses and sharks and rays, among others. Yet historically the marine world has received less attention than its terrestrial counterpart. For that reason, it’s not widely known that the ocean also harbours intelligent beings.
Only in the past few decades have scientists begun to peel back the layers of ocean intelligence. The discoveries have been both surprising and enlightening. What has this research told us about the intelligence of marine organisms? And how does it affect the ways in which we view our own intelligence?
When scientists conduct research on animals to explore their inner lives, what exactly are they studying? In the broadest sense, consciousness equates to ‘I think, therefore I am’. To unpack this abstract idea, experiments explore the facets of consciousness, namely sentience, self-awareness, cognition and intelligence. Sentience is the ability to feel sensations, while self-awareness refers to the understanding that one is an individual separate from others and the rest of the world. Cognition is simply information processing: the ability to perceive and acquire knowledge. Intelligence goes a step further, requiring the organism to consider something that’s been perceived and successfully apply that knowledge to solve problems. Intelligence is influenced by the survival requirements an animal faces in its own environment; it is inferred by scientists by assessing behavioural flexibility. Have these concepts been found in marine organisms? Undeniably, but it’s taken a while to get here.
For centuries, science adopted the views of the 17th-century French philosopher René Descartes. He claimed that non-human animals were not conscious and therefore could not reason or learn, didn’t feel pain or have language; although they were living creatures, they were like mechanical robots. Homo sapiens, on the other hand, was the pinnacle of creation at the end of a long yet discontinuous progression of increasing complexity that leaped from the animal kingdom to humans. Under this anthropocentric view, anthropomorphism (attributing human characteristics to other animals) was not just taboo but completely wrong, and we were prompted to categorically deny consciousness in other animals.
In Beyond Words, Carl Safina sums up our centuries-long mistake by saying, ‘Not assuming that other animals have thoughts and feelings was a good start for a new science. Insisting they did not was bad science.’ Anthropomorphism is certainly not the best model for understanding the minds of other animals since it still uses humankind as the benchmark for comparison. However, it does allow for a degree of understanding with regard to a possible evolutionary connection between animal behaviours and our own.
Thankfully, today Descartes’ claims are considered unfounded due to a greater understanding of brain structure and function and of evolution. For instance, in 2015 Herzing and Johnson showed that dolphins have a complex and well-developed paralimbic region similar to that in humans for processing emotions, setting goals, motivation and self-control. Similarly, bony fishes and elasmobranchs (sharks, rays and skates) have a region called the pallium, which is present in all vertebrate brains and equivalent in function to a human brain’s hippocampus, amygdala and neocortex. The pallium functions in learning, memory, individual recognition, play, tool use and cooperation. In 2016, scientists Byrnes and Brown showed that Port Jackson sharks display individuality and personality traits, which may influence their prey choice, habitat use and activity levels.
Evolution tells a meandering yet clear story that links us as Homo sapiens to all life forms on earth. Sure, humans are more closely related to some species than others, yet many cognitive commonalities, like biological commonalities, are due to shared ancestry. Humans are animals with inherited sensations and inherited nervous systems. We share enough similarities in brain structure and function to believe that the underlying traits of consciousness and sentience evolved long before our own species. After all, Mother Nature is conservative. In 2012, the Cambridge Declaration on Consciousness finally concluded that non-human animals, including all mammals and birds, and many other creatures, such as octopuses, possess consciousness.
Suspend your biases for a moment and consider that every living animal is intelligent in some way. Not in the same way, but in a way that makes their own existence possible. Would we treat animals differently? Marine animals are not granted the same amount of moral consideration as are many terrestrial mammals, in part because of the gap between our perception of their sentience and its reality. However, marine animals are without a doubt sentient and intelligent beings, as shown by their self-awareness, tool use, memory and cooperation.
When was the last time you looked in a mirror? Did you recognise you were seeing a reflection? Did you recognise yourself? If you did, congratulations: you’re self-aware! Or so the mirror self-recognition (MSR) test would conclude. Since its design in 1970 by Gordon Gallup, the MSR test has been used in countless experiments to assess self-awareness in non-human animals, including primates, elephants, dolphins, manta rays and fishes.
In 2001, after the great apes passed the MSR test, Diana Reiss and Lori Marino conducted it with dolphins. In the experiment, a mirror was placed in the aquarium tank and the dolphins were marked in locations that could not be seen without a mirror. Sure enough, the dolphins spent more time gazing at themselves in the mirror when they were marked than when unmarked. One dolphin with a mark on its tongue even opened and closed its mouth to see it! No dolphin showed any social behaviour towards the mirror, indicating that they recognised the reflections as themselves rather than another individual. And just like that, evidence showed that self-awareness was not isolated to primates (elephants were also added to the list).
Then, in 2016, self-recognition was recognised in a cartilaginous fish. Csilla Ari and Dominic D’Agostino gave the MSR test to two giant manta rays in The Bahamas. The rays displayed specific repetitive behaviours, like bubble blowing, frequent cephalic fin movement and exposing their ventral side to the mirror only when in front of it. These behaviours enabled the rays to see whether the image moved when they did and also see parts of their bodies they cannot usually see. As in the dolphin study, no social behaviour was observed. The researchers concluded that the rays perceived their reflection to be themselves and therefore have some concept of self-awareness.
Although bony fish species have been given the MSR test, to date none has passed. However, scientists like Cullum Brown blame flaws in the test for the absence of evidence. Fish rely more heavily on chemical cues for navigating their world than they do on vision. Since visual self-recognition in their environment would be relatively useless, they are not likely to have developed it. Thus, fish are more likely to display olfactory self-recognition. Experiments exploring this have yet to be carried out.
Other scientists, like Carl Safina, have criticised the test for its over-simplicity. They assert that the MSR test does not actually test for self-awareness, but rather whether an animal understands reflection and what it represents. Because some species like fighting fish attack their reflection, it was believed they lacked self-awareness. However, an animal that does not recognise its reflection only shows that it doesn’t understand reflection, not that it lacks self-awareness. In fact, because it attacks its reflection it clearly doesn’t view the reflection as itself – an important distinction that is also a component of self-awareness. When an animal does recognise its reflection, it is demonstrating that it understands symbolism: the reflection is not actually me, it symbolises me. If that’s the case, dolphins and manta rays, among others, may be capable of abstract thought in addition to self-recognition!
Skilful masters & planners
Before Jane Goodall discovered that chimpanzees use tools, tool use was a defining characteristic of our own species. Since then we’ve discovered that many animals use tools. Tool use – defined as an action that involves an agent to achieve a goal – is an interesting way to assess intelligence, as it hints at the ability to plan for the future and anticipate outcomes. While only a few interesting cases are highlighted here, in 2013 Janet Mann and Eric Patterson completed a review of 30 known tool uses in marine animals. For marine species, tools were employed for three main identified reasons: protection, parental care and foraging.
It’s not difficult to imagine a chimpanzee using a tool, but a mollusc? For nine years, Julian Finn and his colleagues witnessed veined octopuses in Bali, Indonesia, carrying coconut shell halves and hiding in them. Equipped with six arms and two legs, they would slide over the top of the shells and while some arms would grasp the husk, the other arms and legs would scuttle across the ocean floor to a lair. The soft-bodied cephalopods would then hide beneath or inside the shells, using them as a protective shelter. Seemingly, the octopuses were planning for the future and weighing the costs and benefits: while travelling with the coconut shells they would be vulnerable to predators, yet once inside or underneath their shells they would be safe. Even species like crabs can be seen carrying or wearing objects for protection and concealment.
Humans use a variety of tools to look after their babies, including bottles, strollers and baby monitors. Surprisingly, fish do too. One in four fish species devotes time to caregiving and the use of parental care tools has been noted in bony fishes like gouramis, whitetail majors, catfish and cichlids. One striking example, depicted in the book What a Fish Knows by Jonathan Balcombe, involves whitetail major damselfish and sandblasting. Before the mating pair lay the fertilised eggs, they remove debris from their chosen site by scooping up sand in their mouths and spitting it onto the rock surface. By fanning the site with water or plucking each grain in their mouths, they remove any remaining sand. Once the eggs have been laid, they may fan them with water to help them stay oxygenated, as do many fish: two instances of tool use in one example!
Water itself can be used as a foraging tool. Just as archerfish squirt jets of water through the air to shoot down insects, stingrays use water to flush out prey. In a 2009 study by Michael Kuba and colleagues, frozen shrimp or pieces of squid were placed inside a plastic tube. One end, painted black, was covered with mesh that prevented the largespot river rays from getting the food, whereas the white end was open, allowing food to be extracted. The rays not only learned they could retrieve food only from the white end of the tube (evidence they respond to visual cues), but they also employed various methods to obtain it: they used their bodies like suction caps, undulated their fins to create waves and blew jets of water into the tube. Each stingray learned to use water as a tool in order to get its meal. One of them never made an incorrect choice, always going to the white end of the tube that it knew would be open. This experiment mimicked foraging situations in which prey might be hiding or unreachable in the wild. For instance, the cownose ray and eagle ray have demonstrated that they use water jetting from their mouths to uncover prey hidden in the sand.
Three-second memory no more
If you kept a goldfish when you were young, you probably believed it suffered from short-term memory loss. Remember the anecdote about fish having a three-second memory? Or forgetful Dory from Finding Nemo? Happily, this couldn’t be further from the truth. The ability for animals to remember certain events, locations, skills or other stimuli over long time periods is advantageous to their survival, just as it’s advantageous for us to remember where we live and who are our family members.
It is currently not known how and where sharks process and store memory. However, research has shown that grey bamboo sharks have similar cognitive abilities to birds, monkeys and humans when it comes to memory and understanding optical illusions. In an experiment conducted by Fuss and Schluessel in 2015, sharks were taught to recognise and remember a specific shape (either a triangle or a square). Then the researchers tested their ability to transfer that knowledge and identify the same shape created by Kanizsa figures, which are illusory diagrams that trick the brain into seeing shapes that are not actually there. The sharks responded just as humans do: they saw and selected the shape they were trained to identify. They were also taught to select a hollow square on a background of diagonal lines over a similar rhomboid and to recognise Müller-Lyer deceptions (differences between line lengths). One year later, the sharks were retested… Surprise! The researchers found evidence that sharks have long-term memory. The sharks remembered their training and selected the same shapes and line lengths they had been trained to pick in the past.
Bony fishes are also able to retain long-term memories. As Cullum Brown describes, many fishes are social learners, in that an individual learns a task or piece of information from other individuals. When that knowledge passes through several generations it becomes a cultural tradition. The migration routes of fishes exemplify social learning and how memories can be passed down through generations for navigation and survival. Negative experiences, like being exposed to painful stimuli, also help solidify a memory. Over a century ago, Jacob Reighard showed that when sardines were dyed red, modified with stinging tentacles and fed to snapper fish, the snappers learned to avoid them and continued to avoid them 20 days later. Similarly, previously hooked fish, like pike and carp, showed hook-shyness for over a year after the event.
Unlike sharks or bony fishes, cephalopods are not vertebrates. They are so far removed from our own species in evolutionary terms that our last common ancestor was about a billion years ago. Yet it turns out that cuttlefish have episodiclike memories, or the ability to recall particular events. This has provided credence to the parallel evolution of memory.
In 2013, Jozet-Alves and colleagues provided cuttlefish with a choice of food (shrimp or crab) and placed each in a different location in an aquarium and with a different visual cue. Shrimp, the preferred food choice, was replenished only three hours after the cuttlefish had eaten it, whereas crab was replenished every hour. The cuttlefish learned that if they had eaten the shrimp less than three hours before their release into the aquarium, there was no point in checking the shrimp location, as shrimp would not be there. Instead, they would swim over to the crab location for their meal. If it had been longer than three hours, however, the cuttlefish would check the shrimp location first!
Unexpectedly, the cuttlefish kept track not only of what they had eaten, but also when and where they had eaten it. By doing so, they were able to maximise their foraging time – a beneficial behaviour in the context of the open ocean. Memory is so important to animal cognition that it did not evolve just once in our own evolutionary line; it expanded throughout several lines simultaneously – an example of convergent evolution.
Plurality of partnerships
Cooperation between individuals requires a high degree of social intelligence and is most commonly found in species living in complex social groups. It’s a complicated agreement, in which all individuals within the group must have a shared understanding of not only what one individual needs from its neighbour, but also what that neighbour needs from the individual – and how they can reach their common goal together. Therefore, cooperation is a wonderful measure of another facet of intelligence. Cooperation is well known in humans and other primates, but what about marine organisms? Do they cooperate and if so, with whom?
Cooperation within a species is quite common. Consider lions or wolves, which hunt together in a coordinated effort to bring down prey. After all, you’re familiar with your own species and what other individuals need. Cooperative breeding is an example that is found not only in birds, but also in fish. An individual fish will give up breeding in order to help rear the offspring of another individual and provide additional parental care and protection. Cooperation for food is another example. In 2008, Visser and colleagues observed for the first time how several killer whales worked together to isolate a fur seal on an ice floe and flush it off by creating waves with their bodies and tails. The coordination and complexity of their actions showed they were communicating about their individual roles and how they could accomplish the feat. This has also been seen as evidence for killer whale tool use, since the killer whales used waves proactively with a goal in mind.
Many marine animals cooperate with members of other species, as shown in a study by Bshary and Noe in 2003. Cleaner wrasses remove dead skin and parasites from ‘client’ fish that signal to the wrasse they would like to be cleaned. A fair trade: a meal for a cleaning. Wrasses were able to differentiate between transient and local clients as well as predator and non-predator, which helped them decide whom to service first (transient before local), if at all (predators).
Some cooperation starts with direct communication. Researchers Bshary in 2006 and Vail in 2013 with their colleagues found that when hunting, groupers will elicit the help of another individual to snag a meal. A deliberate gesture from the grouper, like a head shake, will draw the attention of a partner, say a moray eel or Napoleon wrasse, to encourage it to assist in the hunt and point out the location of prey. The two swim off together and when they find the prey, each attempts to flush it out using complementary hunting tactics. Although only one of the hunters will be rewarded with the meal, each has the chance to eat. Working together therefore increases their hunting success rate.
Fish are not the only marine species that cooperate to get a meal. Whitehead and Rendell reported in 2015 that bottlenose dolphins cooperated with an unlikely partner. Along the Brazilian coast, a generational cooperation exists between dolphins and fishermen. When the fishermen head out with their nets and wade into thigh-high water, they slap the surface to let the dolphins know they are there. The dolphins then herd the fish towards the coast and with distinctive dives signal to the fishermen where to cast their nets. Fish that are caught in the nets are the fishermen’s, while those that escape are gobbled up by the hungry dolphins.
In the early 1900s, when whaling was legal, there was similar cooperation between killer whales and whalers in Australia. Upon noticing a humpback whale in the area, the killer whales would drive the humpback towards the whaler vessels. Others would alert the whalers by breaching and lobtailing. When the whalers had successfully harpooned the humpback, they would anchor it to the ocean floor in a gesture of thanks so that the killer whales could eat their favourite bits: the tongue and lips. Then the humpback would be pulled to the surface and brought in for processing – a win-win for all but the humpback!
I have included some of the most notable instances of the intelligence of marine animals in this account, but they are certainly not the only examples. For a more in-depth look at animal cognition, I recommend the following books by noteworthy scientists and authors:
Righting a prejudice
After decades of exploring animal cognition, we’re finally starting to understand we are not the only intelligent life on earth. In fact, our planet is filled with intelligent life above the waves and below. We’ve learnt that many marine animals share similar brain structures and functions with us; that dolphins and giant manta rays have a concept of self-awareness; and that octopuses use coconut shells as tools for future protection, fish use sand to clean their egg-laying site, and stingrays use water as a tool for extracting or uncovering food. We’ve discovered that sharks are capable of retaining long-term memories; that fish can pass down knowledge as cultural traditions and remember negative experiences; and that cuttlefish remember what they have eaten, when and where. And we’ve found out that wrasses and their clients trade a cleaning for a meal; groupers and eels work together when hunting prey; and dolphins and killer whales cooperate with each other and humans to obtain food.
Yes, the earth harbours an ocean of intelligence. To detect it scientists must be creative and resourceful in their approach. In the past, a major limiting factor was study design. Operating from an anthropocentric foundation, we assumed tests that would be appropriate for humans would also be appropriate for other animals. But this assumption was wrong. During a study, researchers discover only what their methods allow them to see. If their assumptions are incorrect, they may be using inappropriate methods to understand an animal’s cognition and intelligence. In other words, the knowledge acquired depends on the methods used.
Every species is uniquely adapted to its own ecology and has a long evolutionary (and cognitive) story of its own. As scientists, we need to design studies that account for this so that we can determine what assumptions and methods are appropriate. Assessing the intelligence of a species based on the ecology of another is like testing whether an octopus can open a jar after seeing a crayfish locked inside. The researchers failed to realise that octopuses depend more on tactile and chemical inputs than on vision for catching prey. When the design was changed and the exterior of the jar was smeared with crayfish scent, the octopuses quickly and easily opened the jar. This example illustrates the importance of a tenet of scientific research: absence of evidence is not evidence of absence.
The more we learn about animal cognition, the more we realise that we are not unique in our mental capacities, but share many cognitive traits with our distant evolutionary cousins. We have had to redefine what it means to be human multiple times in light of research that shows us how ordinary we are. While this can be difficult to accept, we should not be blinded by the lies of anthropocentrism. We should strive to understand our true place in the animal kingdom in relation to animals both great and small.
A final question to ponder: if we admit we were wrong in assuming other animals are not conscious, sentient beings and we’re now armed with knowledge about their complex internal lives, how should our thoughts and actions change when it comes to interacting and managing marine animals? Might they be entitled to greater moral consideration and treatment?