Sentience

Can clownfish count?

My Minion — Sun, 04 Feb 2024 11:38:04 +0000

Can clownfish count? My Minion Sun, 04/02/2024 - 12:38

Ecology & Science

To discern friend from foe, clownfish count stripes. A recent study found that common clownfish displayed aggressive behaviour predominantly towards members of their own species with three white bands, engaging in confrontations lasting several seconds. In contrast, intruders of other species faced milder aggression.

Photographer, source or credit

François Libert

Permission or license

CC BY-NC-SA 2.0 DEED

Clownfish, also known as anemonefish, are feisty critters that vigorously defend their anemone homes from intruders, particularly those of their own species, displaying aggressive behaviour. Anemonefish species living in the same areas exhibit a variety of stripe patterns, ranging from three vertical bars to none, as observed by Kina Hayashi from the Okinawa Institute of Science and Technology, Japan.

Hayashi and colleagues published their groundbreaking discovery in the Journal of Experimental Biology, revealing that common clownfish (Amphiprion ocellaris) possess the ability to count. They conducted experiments, raising young common clownfish from eggs in isolation to ensure they had no exposure to other anemonefish species. The researchers then filmed the fish’s reactions to various anemonefish species, including intruders of their own species, to determine their response.

Stripe patterns

To understand how the clownfish distinguished between species, the researchers isolated small groups of young common clownfish and filmed their reactions to models with different stripe patterns. The results showed that the clownfish paid little attention to plain orange models or models with one stripe, but exhibited increased aggression towards models with three stripes, similar to their response to intruders in the previous experiment. Hayashi suggests that the aversion to fish with two stripes could be related to their developmental stage, as common clownfish initially develop two white stripes before gaining a third.

The study showed that the young common clownfish possess the ability to differentiate between species based on the number of white bars on their sides. This allows them to defend their anemone homes from individuals that may attempt to evict them, while showing less concern towards species that pose little threat to their abode.

Sources

Journal of Experimental Biology

Okinawa Institute of Science and Technology

Proceedings of the Royal Society B

References and further reading

Counting Nemo: anemonefish Amphiprion ocellaris identify species by number of w…

Colour patterns influence symbiosis and competition in the anemonefish–host ane…

On the brink

Main minion — Tue, 02 Jan 2024 13:04:03 +0000

On the brink Main minion Tue, 02/01/2024 - 14:04

Op'eds and commentaries

I give up; I can’t do it anymore. I cannot keep pretending or carrying on as if all is well in paradise.

Photographer, source or credit

psymes

Diving is a recreational pastime, meant to offer pleasure and respite from our hectic work schedules and the relentless flood of troubling news that seems to worsen daily.

We have always strived to write about and focus on the wonderful adventures, the beauty of the underwater realm, and to provide educational infotainment that enhances our experiences and appreciation of what lies beneath the surface.

I believe most of us need such a refuge to recharge, so we can return to work and tackle the world’s problems with a refreshed mind. It has been a guiding principle in assembling this magazine to provide such a sanctuary, a break from the daily grind. That being said, it does not mean we should bury our heads in the sand when it comes to reporting on environmental challenges and realities.

We are probably all now acutely aware of the precarious state of the global natural environment. It is under siege everywhere. Most notably, coral reefs across the planet are in dramatic decline, if not outright dying. We must now ask ourselves: How did it get so bad and why did we let it happen?

There are positive signs and trends, such as the resilience of some corals and reefs against rising temperatures. In the past, it has been equally important to report on these glimmers of hope, and it still is.

In this issue, we publish a report by Robert Osborne on a coral bleaching event at one of his favourite reefs in Cuba, which he visited last fall. It brings me no joy, but we have reached a point where we must confront these issues head-on, if we are to stand any chance of effecting positive change. Ignoring them only perpetuates business as usual. But the “usual” is a dead end. The old ways have led us to this dystopian predicament. We must change course while there is still a chance to act.

Can we act? We certainly can, if we are willing and prepared to pay the price, because it will not come cheap. At countless COP summits, heads of state have wrung their hands and repeatedly promised decisive action, only to forget about it as soon as the press conferences end. But perhaps, as more countries are battered by climate change, droughts, floods and other calamities—all of which have major economic impacts—they will finally awaken and act.

Some changes are already irreversible, and developments have been set in motion that can no longer be stopped. But if we commit our hearts, minds and resources, much can be done to stem this accelerating deterioration of our natural ecosystems, and to repair and restore what has been damaged.

It is not a difficult choice. In fact, it is not a choice at all.

— Peter Symes
Publisher & Editor-in-Chief

Sentience

Editorial

A Return to the “Old Normal” in the Dive Industry

Main minion — Fri, 01 Dec 2023 11:50:35 +0000

A Return to the “Old Normal” in the Dive Industry Main minion Fri, 01/12/2023 - 12:50

Op'eds and commentaries

DEMA show 2023 felt like a return to the “old normal" but is that a good thing?

Photographer, source or credit

psymes

We have recently returned from another DEMA Show, and it is heartening to witness the dive industry’s resurgence following the pandemic. The show felt like a return to the “old normal.” However, there is an intriguing duality at play here—the old is becoming the new normal in the dive industry.

With nearly three decades of experience in the dive industry, I may be considered a senior member by conventional standards. Yet, at many dive shows, it does not quite feel that way. Amid the attendees, you will find plenty of grey hair, a few walkers, and even some mobility scooters.

It is no secret that the dive industry faces a significant demographic challenge. The older generation proudly identifies as divers, while younger cohorts often view diving as an item on a checklist, a fleeting experience during vacations. This dwindling retention of divers, who do not progress in their certifications or continue to explore the underwater world beyond occasional holidays, has long eroded the industry’s economic foundation.

So, what has changed? One argument suggests that activities and lifestyle preferences fluctuate in popularity, and diving may have peaked around the turn of the century before gradually declining. While this may hold some truth, I find there is a deeper factor at play.

When my generation, now in our middle years, were children, diving was an unattainable fantasy. Seeing it on TV felt like watching science fiction, igniting our dreams. As dive training gradually became accessible, a door to those dreams began to crack open. As a university student with limited funds, I joined a dive club, piecing together my gear through borrowed, ill-fitting equipment. It took months of club meetings and Tuesday evening training sessions in a public swimming pool before we earned our coveted C-cards.

We were immensely proud because, at that time, certification was a significant achievement, a symbol of prestige. However, just a decade later, you could be at a dinner table, and Aunt Agatha might casually mention her PADI Open Water certification from a trip to Thailand, and no one would bat an eyelid. That is when diving lost its allure for the younger generations, sowing the seeds of its decline.

How do we make diving cool again? I don’t have all the answers, but there are promising signs of a resurgence in some regions, particularly in Asia and pockets of Europe. Additionally, younger divers are increasingly championing environmental causes, participating in underwater clean-ups, coral planting, and reef restoration efforts. It is not just cool; it adds a profound new dimension to being a diver, and that is something to be optimistic about in the ever-evolving world of diving.

— Peter Symes
Publisher & Editor-in-Chief

Sentience

Editorial

The price we have to pay

Main minion — Mon, 23 Oct 2023 08:43:31 +0000

The price we have to pay Main minion Mon, 23/10/2023 - 10:43

Op'eds and commentaries

From Flights to Fins: Making Sustainable Choices in a Travel-Dependent Industry

Photographer, source or credit

psymes

I have just booked my flight to the DEMA Show—the world’s largest dive show and industry event. When I made my reservation, I selected Scandinavian Airlines because they now offer travellers the option of purchasing sustainable biofuel as part of the flight ticket, so one can fly with lower CO2 emissions. I also opted to pay for a full carbon offset of my trip. It hurt my wallet, but it lifted the ache I had in my tummy. Being a transatlantic trip, it did not come cheap, but I do not see that one has a choice any longer.

I cannot in good conscience go on and on about how we should protect the environment and do whatever is necessary to save the planet for future generations, and then just climb aboard an intercontinental jet as if it were business as usual. That would make me a hypocrite of the worst kind.

Proven-effective carbon offset

Some sort of proven-effective carbon offset, or purchase of biofuel, should, in fact, be included in the ticket price, because it would be naive to think that more than a few of us would ever voluntarily pay more than strictly necessary for our flights. We all go shopping for bargains or the lowest price. That is how the free market and human minds work.

Such measures would likely make travel significantly more expensive in the short term until the necessary infrastructure has been developed and deployed. But then again, do we really have a choice any longer? I think not.

That being said, I am painfully aware that this position is probably not going to win me many friends in the dive industry which, after all, is largely dependent on a well-functioning travel sector. But we all have to adapt, and the sacrifices we have to make need not be all that hard. It is mainly a matter of priorities, such as giving up or postponing the purchase of another shiny new toy or working a few extra hours. Or it is a shift in perspective. In both the short and long term, it is an investment in us, as a species, and our only home, Earth.

Choose wisely

But we must be selective and choose wisely. Not all carbon offset projects are equal. Some are not effective at all or even add carbon emissions. A recent analysis by The Guardian and Corporate Accountability revealed that the majority of the most frequently used offset projects were “likely junk.” In response to widespread concerns about carbon offsetting credits, new quality standards for the carbon offset industry were published by the Integrity Council for the Voluntary Carbon Market (ICVCM), so buyers seeking high-quality credits can look for the ICVCM stamp of approval, The Guardian reported earlier this year.

Let us not forget that diving is a luxury, not a necessity like food and clean water, access to medical services, and basic safety. If we want to indulge in our chosen luxuries, we must accept that there will be a price to pay, and it should not be at the planet’s expense.

Right thing to do

Instead, consider it an insurance policy, an investment, a legacy, or a gift to the next generation, our children and grandchildren, and those who are already suffering from the effects of climate heating. They will never forgive us if we do not step up, act and do what is rightfully expected of our generation.

Ensuring that there is some sort of effective carbon offset or sustainable biofuel associated with your purchases of travel, however imperfect the various current schemes may be, is quite a small price to pay in the grander scheme of things. Above all, it is something we can all do.

— Peter Symes
Publisher & Editor-in-Chief

Sentience

Editorial

Justice for All Sentient Beings?

Main minion — Thu, 31 Aug 2023 13:46:26 +0000

Justice for All Sentient Beings? Main minion Thu, 31/08/2023 - 15:46

Op'eds and commentaries

What counts as sentient? We can't know. I therefore do not take anything for granted but acknowledge that even the smallest and seemingly insignificant creature just might be capable of some degree of sentience.

I am therefore I think. Because I think, justice should also be extended to me?

Photographer, source or credit

psymes

Most of us will agree that we should not be cruel to animals but treat them nicely. We have animal welfare laws in place, for example, and pet owners will testify that their animals—often considered members of the family—have personalities and feelings. It is also widely accepted that a number of wild animals possess considerable intelligence and social skills, such as primates, marine animals, and some birds, to name a few.

Some animals even have certain rights or protections. Neglecting or mistreating pets or livestock is, in most places, a crime and animal welfare laws dictate that livestock should be provided with tolerable living conditions and enough stimuli, and they should not suffer any unnecessary pain.

But which animals do such rights and duty of care extend to? Just the familiar species, such as those we keep as pets, raise as livestock, or think are cute?

How about the sentient beings we encounter in the ocean?

Our appreciation of sharks has come a long way since the days when they were considered fearsome monsters and single-minded eating machines to our current understanding of them today as quite intelligent and sentient beings, with social interactions and structure. But does that mean they should also have legal rights?

The prominent philosopher and ethicist Martha Nussbaum thinks so.

Her “Capabilities Approach” is a philosophical framework that aims to provide a more comprehensive and human-centred perspective for evaluating well-being and social justice.

In her recent book, Justice for Animals (which I aim to review in the future), she argues for an expansion of her influential approach, to encompass all sentient beings. She makes a good case albeit one fraught with challenges, including some cultural and legal in nature.

It also made me speculate what counts as “sentient.” As we have frequently covered in this publication, even smaller fish have cognitive skills once thought way beyond them, and feelings too. Crustaceans are known to feel pain, fear and stress, and are likely to also have cognitive skills that we just have not documented yet.

But what about even smaller critters? What, if anything, do they think and feel? There simply is no agreed to minimum size of brain considered capable of supporting sentience, so we cannot rule it out.

The philosophical, ethical and legal implications are enough to make my brain hurt. That being said, it is quite clear that sentient beings matter, and we must do better by them.

When I dive, I therefore do not take anything for granted but acknowledge that even the smallest and seemingly insignificant creature just might be capable of some degree of sentience.

This realisation has not only left me more careful and respectful around other life forms, but has also added to the sense of wonder, profound as it already is, that has made diving so fulfilling.

Sentience

Editorial

Sharks as social and sentient beings

Main minion — Mon, 28 Aug 2023 05:04:49 +0000

Sharks as social and sentient beings Main minion Mon, 28/08/2023 - 07:04

Ecology & Science

Recent research about sharks challenges perceptions, revealing their advanced cognitive and emotional capacities.

Research has begun to challenge the long-standing perception of sharks as solitary hunters, revealing instead a complex social structure that requires a high level of cognitive function.

Photographer, source or credit

Peter Symes

Recent scientific research has begun to challenge the long-standing perception of sharks as solitary hunters. Rather, it reveals their complex social structure that is borne out of a high level of cognitive function.

In fact, these studies suggest that sharks possess a level of social intelligence, problem-solving skills and even emotional intelligence that far surpass previous beliefs, offering a fresh perspective on their behaviour and potential sentience.

Social intelligence in sharks

A comprehensive review of Chondrichthyan cognition (Chondrichthyes: cartilaginous fishes) published in the journal Animal Cognition provides empirical evidence of consistent and repeatable social networks among sharks. Despite changes in group size, the social network position of individual sharks remained consistent, thus suggesting that it was social preference that drove network structure.

The review highlights that the handful of species that have been cognitively assessed in some detail over the last decade have provided enough data to safely conclude that sharks and rays possess a high level of cognitive function.

Social groups

Further research published in the journal Animal Behaviour revealed that sharks form spatial groups characterized by nonrandom and long-term associations. These groups were found to be influenced by individual preferences and adaptation to local conditions, suggesting that the grouping patterns were due to an active choice of individuals, a sign of sociability.

It has also been documented that blacktip reef sharks did not form groups randomly or passively. Instead, their communities developed from an active selection of specific individuals, as a sign of sociability.

Fish Biology published a study on Port Jackson sharks, demonstrating highly repeatable individual differences in boldness and stress reactivity. This study provided the first evidence of individual personality differences in sharks, a crucial aspect of social intelligence.

Social learning

Another study in Animal Cognition showed that juvenile lemon sharks are also capable of social learning. Researchers observed that they were more likely to follow the path of another shark that had previously found food, suggesting they could learn from the experiences of their peers.

This was also the case with juvenile Port Jackson sharks which learned the route to a hidden food reward when they could interact with a previously trained shark. Compared to individual learners, sharks that had the chance to see others perform the task took fewer days to master it, and more of them were successful.

This shows that sharks, like many other animals, can use socially derived information to learn about novel features in their environment.

Problem-solving abilities

Beyond social intelligence, sharks have demonstrated problem-solving abilities. Sharks can adapt their behaviour based on new information. This level of cognitive flexibility was once thought to be exclusive to higher mammals.

Sharks and rays are intelligent and inquisitive creatures with surprising behavioral flexibility.

Sources

Nature

Biology Letters

Fish Biology

Animal Cognition

Animal Behaviour

References and further reading

Smart sharks: a review of chondrichthyan cognition

Learning and robustness to catch-and-release fishing in a shark social network

Evidence of social communities in a spatially structured network of a free-rang…

Shark personalities? Repeatability of social network traits in a widely distrib…

Individual personality differences in Port Jackson sharks Heterodontus portusja…

Social learning in juvenile lemon sharks, Negaprion brevirostris

Sentience

Sharks

Do octopuses have an emotional life?

Main minion — Sat, 30 Jul 2022 10:12:35 +0000

Do octopuses have an emotional life? Main minion Sat, 30/07/2022 - 12:12

Ecology & Science

There is a growing consensus that octopuses are most likely sentient.

Giant Pacific Octopus interact with divers

Photographer, source or credit

Andrey Bizyukin

Octopuses have intrigued scientists for years, because they have both long- and short-term memory, they remember solutions to problems, and they can go on to solve the same or similar problems. They have been known to climb aboard fishing boats and open holds in search of crabs. They can figure out mazes, open jars, and break out of their aquariums in search of food.

They are obviously acutely intelligent and able to learn novel tasks and orient themselves within their environment, and it has been observed that octopuses apparently dream.

As many researchers and aquarium technicians have noted, octopuses adapt to being captured in a few days, unlike many other animals. The change is from a fearful animal to almost pet-like—friendly and very alert about all that is occurring nearby. Octopuses respond rapidly to rewards and are extremely curious and responsive. They focus on any new object they see.

How do they get so smart?

Complex cognitive abilities, such as causal reasoning, future planning, and mental attribution (an individual’s ability to recognize the thoughts and knowledge of others), are a signal of advanced, higher-order thinking that is usually only observed in vertebrates, rather than animals like snails and mussels. Against all odds, cephalopods produce highly intelligent behaviours that transcend common evolutionary reasoning.

How did a mollusc such as an octopus, a solitary creature with little social life, become so smart? Their body plan and nervous system are so very unlike our own. Rather than having a single central brain where all sensory information and motor controls are processed, they have a partially de-centralized nervous system with nine brains, with smaller brains in each arm. The central brain, which is located between its eyes and contains about 180 million neurons, may simply delegate orders, while the arm is responsible for deciding exactly how to execute the order. The peripheral nervous system is made up of around 300 million neurons.

What do they feel?

It does beg the intriguing question of whether sentience is advantageous for survival in a Darwinian sense and therefore bound or likely to follow, in some shape or form, from having a complex nervous system?

We'll leave you with that to ponder. Here is a little selection of the many videos laying around documenting the intriguing behaviour of these molluscs:

References and further reading

Lobsters, octopus and crabs recognised as sentient beings

Do octopuses dream?

Sum Won — Thu, 01 Apr 2021 15:32:48 +0000

Do octopuses dream? Sum Won Thu, 01/04/2021 - 17:32

Ecology & Science

Shifts in colour, behaviour and movement are evidence of a sleep cycle -- with the octopus switching between active and quiet sleep just as humans switch between deep sleep and REM sleep --suggesting that octopuses may experience something akin to a dream.

Their apparent problem-solving ability has led cephalopods to be recognised as intelligent.

Photographer, source or credit

Composite graphic based on image by DaugaardDK

Permission or license

CC BY-NC-SA 2.0

Scientists used to think that only mammals and birds experienced different sleep states. More recent research, however, has revealed some reptiles and cuttlefish -- another cephalopod and relative of the octopus -- show non-REM and REM-like sleep.

A new study has found that the octopus has ‘quiet’ and ‘active sleep’, with different episode duration and periodicity, and experiences active sleep after a long episode of quiet sleep.

States differ on arousal thresholds, skin colour and texture, and eye and mantle movement. Octopuses usually change their skin colour for camouflage or for communication but during sleep, environmental factors no longer trigger these patterns.

How do we know?

Octopuses have a very different brain structure to humans, so how can we know that they dream, or even sleep?

Electrophysiological recordings in mammals show distinct spectral profiles that comprise two major alternating sleep states, one quiet and another active. Much less is known about neurobiological rhythms in invertebrates because electrophysiological recordings remain very challenging in these animals. Despite these limitations, the study of invertebrate sleep has advanced using behavioural criteria originally developed to investigate mammalian sleep.

Among cephalopods, the common octopus (Octopus vulgaris) meets all the criteria to define sleep

The octopuses were very sensitive to very weak stimuli when they were alert, but in both sleep states they needed a strong visual or tactile stimulus to evoke a behavioural response, the scientists said.

"It is not possible to affirm that octopuses dream because they cannot tell us that, but our results suggest that during 'Active sleep' the octopus experiences a state analogous to REM sleep, which is the state during which humans dream the most," wrote the study authors Sidarta Ribeiro and Sylvia Medeiros in an email to CNN.

Quiet with half and half body pattern (‘QHH’) recorded during the day

Sources

iScience (Cell)

References and further reading

Cyclic alternation of quiet and active sleep states in the octopus

Thoughtful Sharks

Ila France Porcher — Thu, 03 Jan 2019 23:40:28 +0000

Thoughtful Sharks Ila France Porcher Fri, 04/01/2019 - 00:40

Ecology & Science

Long term study of the behaviour of individual sharks has shown that they are not just acting on instinct. They are thinking and highly intelligent, and likely conscious too.

Portrait of a Tiger

Photographer, source or credit

Ila France Porcher

So as the Year of the Shark in 2019 begins, here is a review of how their actions reveal some of their mental states.

The usual methods for studying sharks are through tagging and dissection rather than through observing their actions underwater. However, direct observation of the actions of many individuals is the method, termed “ethology” normally used to study wild animals on land. So over a period of fifteen years, I searched out and observed the reef sharks on different islands in the South Pacific and for seven years studied the population of blackfins intensively as individuals. By recording their actions I was able to access a dimension of their lives that had not previously been documented. My records ultimately included 581 individuals and I could recognize 300 different sharks on sight.

Their complex behaviour soon showed that the sharks were using reasoning, rather than reacting automatically to their environment as had been assumed. Cognition, the process of knowing through thinking, is the term used for thinking in animals. An animal shows that it is using cognition, rather than trial and error, when it must have referred to a mental representation in order to act as it did. Many life forms, including invertebrates, are increasingly found to be using cognition in their daily lives, and cognition in fish has been well studied.

Vigilance

Wild animals are always vigilant, always on the lookout for danger, and sharks are no different. Whenever anything was different about my visit, whether it was in a different place or at a different time, their behaviour became more cautious.

All of the species of sharks I observed use the visual limit to conceal themselves. Once out of sight, they continue to pay attention from beyond visual range, by listening and through their lateral line sense. Occasionally they pass into view to look. If the shark is interested enough, its approaches bring it closer each time. Some species, such as tigers, pass above the object of their interest—for example, a diver—while others tend to approach horizontally.

In the case of blackfin reef sharks, the approach becomes more direct with each repetition and the shark turns away at a more acute angle each time. Its closest approach may bring it up to the diver’s mask before it turns away. This close approach is occasionally done very fast in order to intimidate, for example when the shark is trying to force a spear fisherman to give up his fish, however, the sharks who came to know me best would perform it slowly, one after another, when I first arrived, as if it were a sort of greeting.

The older female sharks, which are the largest individuals, were the shyest. Elderly blackfins would often linger out of visual range, making few passes into view and never coming close, while excited bands of males coming into the shallows to mate after sunset would zoom straight up to me on first meeting.

Other species tended to approach by making repeated passes in a straight line, coming closer to the diver each time, but rarely closer than two metres.

On the few occasions that I brought another person with me, the sharks sometimes vanished beyond visual range when the visitor appeared underwater. Many minutes would pass before they came back and they would arrive in long lines led by the boldest among them. In single file, they would glide straight up to the stranger, after which they milled around and if I had brought food, they would not eat.

This behaviour demonstrated their alertness to changes, and their ability to make quick decisions based on unexpected findings. Memories of events that can be called upon for decision-making are called declarative memories and are considered to be evidence that the animal is conscious.

Fishermen who complain that shark feeding dives cause sharks to harass them have failed to understand this crucial point―sharks easily discern the difference between a shark feeding event and a spearfisherman. It is the fishermen themselves who attract sharks, by holding dying fish underwater and trailing scent.

Knowing Others as Individuals

Individual differences marked each shark’s behaviour. Each one had a unique pattern of roaming, under the dual influences of the lunar phase and the reproductive cycle. Some were nearly always present in their home ranges, while others travelled for months at a time. Individual sharks demonstrated different rates of learning, and they varied greatly in their responses to different situations. They had complex social lives and their behaviour was flexible depending on the circumstances.

The sharks recognized each other as individuals, which is the prerequisite for the complex social lives in which cognition is most evident. Blackfins travelled widely, and tended to go with preferred companions. At times they joined with others residing in the regions they passed through. There was always excitement when travellers and residents met, and since they are not territorial, there was no aggression. They would follow each other and swim side by side for long periods, often in a state of excitement, before the companions moved on.

Companions were individuals of the same gender, and usually the same age as well. Some sharks usually travelled alone, some always with the same companion, and others changed companions. Due to the circular paths in which they move, they repeatedly crossed each others’ scent trails, and thus remained in loose contact as they roamed, together, yet not usually within visual range.

As far as I was able to determine, such friends came from the same region. The reef sharks were acquainted with the other individuals whose home ranges overlapped theirs and their travelling companions were usually neighbours at home.

Bonnethead sharks, too, have been shown to recognize each other as individuals, and at least some species of sharks and rays choose their mates, providing further scientific evidence that individuals know each other.

Memory and Learning

Learning plays an important role in the lives of sharks, as has been well documented. Learning is closely involved with memory, and the sharks I knew showed an ability to remember events far back in time. Familiar sharks recognized me in the lagoon as much as two years after their last meeting with me, and their behaviour, of greeting and travelling with me, was unchanged.

Like people, different sharks had different rates of learning. For example, among those who accompanied me most often, one of them never learned to take a treat I threw for her, while only a few caught on immediately without practice.

Hiding

Often a shy shark who appeared briefly in visual range would suddenly pass close behind me, but dart away if I turned and saw her—she had come to look without being seen. Sharks easily understood the direction in which a person was looking. In other ways, too, they showed that they were aware of whether or not they could be seen. When I was with another person, for example, they would swiftly approach for a closer look when we raised our heads above the surface to talk.

Once I was swimming with my step-son, and he climbed on a dead coral structure to look around above the surface. The shark who was accompanying us swam over to sniff his legs, and with his head above the surface, the boy never saw her.

Sharks also surprised me by swimming between my face and hands when I was drawing their dorsal fins for identification purposes; this never happened when I was paying attention to them. One unusual shark passed me nearly every time I went to the lagoon, drifting by from left to right, always and only when I was looking the other way. She did this for eight months before relaxing her vigilance and moving around me more freely.

Always on the alert, the sharks used their awareness of whether or not a person could see them to their advantage.

Therefore, it is not surprising that you never see the shark who bites you. As with other predators, it is best to face them, and pay attention to them when you are with them. But, that said, shark bites are very rare. Sharks were the only wild animal with which I was in intimate contact for many years, and who never bit me, either through accident or irritation.

I eventually concluded that sharks have an inborn inhibition against biting companions, or others of their own species. This is well known among species that have evolved dangerous weapons, though not in humans, the only large predator who invented, and did not evolve, its weapons. During fights, for example, no wolf or dog will bite another who rolls on his back in submission, but humans will kill people who are begging for mercy.

Attention, Curiosity and Observation

The sharks were very curious and investigated anything new. If a coconut floated across the surface, one would notice and rise to sniff it, followed by the others. They would often follow me for long distances, sometimes for hours, while remaining hidden beyond visual range. From time to time I checked to see who was with me by suddenly stopping, whereon they came into view and I could check their identities. It was surprising that they would remain concentrated on one thing for such a long time.

Sometimes unexpected events revealed patterns I might not otherwise have seen. When one of the sharks became ill, each evening I tried a different tactic to give him a piece of food in which antibiotics were inserted. The other sharks seemed to anticipate each of my attempts, and their actions made it very difficult for me to medicate him.

One of the tactics they used after several nights of missing out on this piece of food, was to wait beyond visual range. When the time came to medicate the sick shark, and I went to the kayak and threw his chunk of food into the water, seven sharks, whom I thought had left an hour earlier, soared in, and the fastest one snatched the treat in mid-water.

Since they had been out of view, they had based their decision to act on a signal they had heard. They had understood the sounds of me getting the treat and throwing it, and their actions were effective because one of them did get the food!

This example shows their ability to predict something that might occur in the future and to concentrate on it. Cognition is indicated because they must have held a mental representation of possible food coming, the signal that would trigger its imminent arrival, and what they planned to do when it came.

It often seemed that the sharks tried to be one step ahead of me. In long-evolved predators who catch swift and evasive fish for a living, the strategy of watching and waiting, and trying to predict from past experience what the prey would do next, could well have been selected for.

Self-awareness

Cognitive ethologist Donald R. Griffin pointed out that when an animal hid from view, it was demonstrating self-awareness. He described how Lance A. Olsen had reported that grizzly bears sought places from which they could watch hunters while remaining hidden. Other observers had reported too, that bears tried to avoid leaving tracks.

The researchers concluded that these bears were aware of being present and observable, as well as creating effects―their tracks―through their movements, which could be seen by others. The sharks’ habitual way of remaining concealed beyond visual limit until an opportunistic moment, or approaching from behind to avoid being seen, is in the same category of behaviour and indicates that they are aware of being present and observable.

This is the reason why the so-called ‘shark counts’ that divers are asked to participate in, have no scientific validity. Since sharks are either attracted to divers or avoid them, the numbers of sharks seen by divers are not representative of the true numbers on the reef. Where sharks are habituated to divers and come to see them, such counts may give the impression that there are many sharks, when actually, their numbers are few.

Further, once the information is published, the sharks are vulnerable to being fished for their fins.

Decision Making

Occasionally reef sharks would flip on their backs to wriggle in the sand, presumably to scratch or to free themselves of parasites. On other occasions, a shark would turn to whip the side of its body against a sandbank. The floor of the lagoon was made up of sand interspersed with reef flats and coral, and the sharks invariably chose only sandy places for such manoeuvres.

Sometimes a shark carefully positioned himself to use a smooth, flat surface of dead coral on which to rub himself. Apparently, he had intentionally surveyed the environment and chosen a suitable structure to use. He must have held a mental image in mind of what he wanted, and referred to it while looking for a formation of the right shape.

Though this may not seem to be very impressive in terms of thinking in sharks, the availability of surfaces to use in this way does not mean that the animal will realize how they can be of benefit. For example, mynah birds (Acridotheres tristis), and junglefowl (Gallus gallus), the wild ancestor of domestic chickens, both spend much of their time foraging for insects on the ground, and both have strong feet for walking. However, mynah birds have not discovered that they can use their feet to help them uncover these insects, while junglefowl do so instinctively.

I was lucky to witness a clear decision made by two sharks, between two possible choices. One day near my study area, I saw the fins of many sharks slicing the surface and found a spawning event underwater. Sharks were gliding among the clouds of dancing fish, occasionally snapping one up. Two blackfins came over when they saw me, and returned from time to time to circle me over a fifteen-minute period. When I left and travelled another kilometre into the lagoon in my kayak, these two sharks followed from the spawning site.

They decided to follow me even though they had not seen me for several months, and they made the choice that was based on a mental reference—a thought or memory—that sometimes I brought food. Yet, they were already in a situation in which they could see, hear, and smell food, moving in a stimulating way, and I had not fed them in that location before. This decision to leave, based on a memory many months old, indicated that they must have made such memories, and referred to them, a clear act of cognition that indicates consciousness.

Communication

I could not see evidence of communication between sharks except through body language. Yet occasionally, companions acted in concert, leaving the other sharks, and swimming in formation to perform a specific act together. How they communicated the decision to do this was not clear, but likely body language played a role.

In his book, The Secret Life of Sharks, Professor Peter Klimley described how great white sharks ritualize their conflict when a seal that one of them has killed comes under dispute. Each slaps the water at an angle with its tail, and the shark who raises the most water and blasts it farthest wins the prey. For this ritual to be effective, each shark must view its opponent’s gesture as a communication, and understand it, since the winner gets the seal without a fight, which could badly hurt both sharks.

Scheduling

Sharks often passed the same place at the same time repeatedly. One young visiting male passed by my observation post about five meters to the right, between ten and fifteen minutes after sunset each night for several weeks. Each time, he saw me and came for a closer look, then turned and went on his way.

Another rare visitor’s first four visits, though months apart, occurred precisely at the moment that the sun touched the horizon, four days before the dark of the moon.

Intrigued, when one of the residents who had habitually met me on my arrival in the lagoon, began coming instead at the end of the feeding session and missing out on the food, I kept careful track of the time of her return. For reasons known only to her, she had suddenly begun to spend her days in the ocean. Over a period of many months, she returned about ten minutes before sunset, night after night. Sometimes, she still met me when I arrived at the study site, yet other times, I saw her return from the sea when it was nearly dark and pass in the distance without coming to the feeding session.

Besides illustrating a remarkable ability to follow a daily schedule, and yet be flexible about it, her actions indicated that she had not become dependent on my weekly feeding sessions, though she had known about them since she had been a juvenile.

The sharks seemed to have no trouble catching a fish when they wished to, and often came to the feeding sessions only to socialize. Resident sharks routinely left for months at a time, and visitors did not remain in the area because of the food. Though many came to my feeding site at the proper time, their long-term schedules were unaffected by the few scraps I provided once a week to facilitate my observations.

Social Learning

The resident sharks learned in time that the fish scraps I brought to the feeding sessions were in the back of my kayak. Though this species has not been documented breaching the surface to eat or to look around, these sharks found that the food could be accessed by leaping from the water, and leaning towards the boat, while snapping at whatever they could locate. The sound of their jaws snapping shut made loud clapping sounds, and some of the kayak’s straps were cut, punctured and sliced by their sharp little teeth.

This behaviour pattern was a new foraging technique they had discovered, that was initiated by one or two sharks and instantaneously copied by the others present. They used it from then on. This discovery happened twice, in different locations, under different circumstances, with different groups of sharks, and is an example of social learning, which is basic to the development of culture.

Under normal circumstances, the space above the surface is not something that these sharks would have reason to consider. But they were presented with an artificial situation in which I came from above the surface and returned there, and so did the food in which they were interested. They would doubtless have stored memories about the surface from the occasions, particularly when they were small, when they swam through it or up against it while chasing a fish, though it is unlikely they could have formed more than a vague impression that there was a space above, from such brief events. Yet, their behaviour suggested that they were aware of a volume above the surface in which things could exist, and from which I came and went.

A question in cognition is whether an animal knows that something continues to exist when he or she can no longer see it. An object apparently ceases to exist for dogs, for example, when it disappears from view. So few people would agree that sharks could understand that I was in my kayak, even when I had just left their company and climbed into it. Yet they were aware. Indeed, the many ways that sharks took advantage of the opportunity to hide beyond visual range, strongly suggests that they understood very well the idea that something continues to exist, in spite of being out of their view.

Conclusion

Sharks have exquisitely coordinated senses, and their behaviour indicated that they used this sensory input alertly to make moment-to-moment decisions, and respond flexibly and appropriately to changing circumstances. They remembered the events in their lives and referred to these memories in decision making. They were curious, but cautious, and learned quickly. Their versatile behaviour, individual differences, and different ways of handling various circumstances were not indicative of a set of stimulus/response reactions.

I have observed sharks underwater in the Bahamas, including bull and tiger sharks, and found that their behaviour was remarkably similar to the behaviour of the requiem sharks I had known in Polynesia. This is to be expected since sharks have been evolving for four hundred twenty million years, and many species travel widely and are found around the globe. The essential qualities that sharks evolved to be so successful would already have developed in the ancestral forms before they evolved into modern species occupying the ecological niches we know today.

Though fish may seem primitive when looking down on them from the altitude of Homo sapiens, in fact, they are highly complex and evolved life forms. And no brain is simple, as anyone who has observed the activities of a spider will appreciate.

Sentience

Sharks

Sand tiger sharks have a friendly side

Main minion — Tue, 18 Oct 2016 14:59:00 +0000

Sand tiger sharks have a friendly side Main minion Tue, 18/10/2016 - 16:59

Ecology & Science

Sand tiger sharks Carcharias taurus, exhibit group behaviour that has historically been associated with higher order mammals.

Sand Tiger Shark. Evidence of complex social behaviors in sharks and other elasmobranchs is sparse, however we are beginning to understand the importance of studying shark aggregations

Photographer, source or credit

User Amada44

Permission or license

Creative Commons

While many sharks are solitary predators, some are known to live in groups and are suspected of engaging in complex social behaviors. Meanwhile others simply aggregate due to similar habitat, food, or mating requirements.

Using a novel tagging procedure, scientists in the United States, have discovered that some shark species like to spend their time mixing and chilling out together.

University of Delaware researchers collected tens of thousands of interactions between the 300 or so sand tiger sharks, fitted with electronic tags, over the past four years. In some cases, the sharks were found to spend up to 95 consecutive hours together.

Brainy

Sand tigers have high brain to body mass ratios when compared to other Chondrichthyes (cartilaginous fishes) and therefore may have the ability to maintain complex social structures and social behaviors such as coordinated group feeding behaviors similar to those observed in marine mammals.

The University of Delaware project was launched in 2012 with only a modest 20 sand tiger sharks involved at first. Each had an implanted acoustic transceiver fitted to study their movements throughout the year. Initially focusing on two male sharks the devices also recorded details of other animals carrying transmitters that came near the two sharks. These included Atlantic sturgeons, white and sandbar sharks, spiny dogfish and also lemon and bull sharks.

They all met up

The two sand tiger sharks did not always travel together, it was found, but they did reconnect at various times of the year and encountered more than 50% of all the other tagged sand tiger sharks on the east coast of the United States.

Sources

Nature journal Scientific Reports

References and further reading

Social Network Analysis Reveals Potential Fission-Fusion Behavior in a Shark

Sharks