Ocean economic boom threatens many potentially conscious species

Rising human exploitation of the oceans is pushing ever further into regions that scientists increasingly suspect are full of conscious life.

New research into creatures from sperm whales to octopuses, reef fish to hermit crabs, suggests that wide swaths of the undersea world may be populated by animals that have forms of consciousness something akin to those in humans.

Those findings are coming alongside a broad increase in the impact of human society on the sea — a rising tide of disruption driven by economic sectors as diverse as increased oil and gas exploration, record levels of fishing and floods of pollutant-filled runoff from agricultural and industrial buildouts into shallow coastal waters.

The great tragedy of ocean intelligence, Macquarie University fish researcher Culum Brown told The Hill, is that the most intelligent sea creatures tend to be the most susceptible to human economic activity.

“Complexity is adjacent to land, and it’s in the places where there are most people,” he said. 

Hubs of complexity “like coral reefs are getting smashed,” he said, “because there’s just so much pressure coming from human populations.”

Behind the immediate threat of direct coastal exploitation is the great pervasive threat of carbon pollution from global fossil fuel burning. That pollution is heating and acidifying the oceans — a primary cause behind the global dieback in coral reefs, which recent research suggests may be hotbeds of sentient, or even conscious, life.

So far, the impacts of scientific discoveries regarding ocean intelligence have been restricted to the slow growth of an international legal campaign agitating for better treatment — or at least better deaths — for animals now believed to be potentially sentient.

In 2018, following a wave of research suggesting that crustaceans can feel pain and make considered choices, Switzerland banned the common practice of boiling lobsters alive. In 2021, the British government followed, officially defining crabs, lobsters and octopuses as “sentient” — meaning they now must be treated, killed and butchered with the same level of care as mammals and birds.

The new research also adds weight to an ongoing legal fight over the responsibility of terrestrial governments to the ecosystems of the ocean. In late May, the International Tribunal on the Law of the Sea found that carbon in the atmosphere counts legally as pollution, and ordered the world’s governments to go further in restricting them.

That decision comes alongside a series of grinding international debates over the ocean economy: how and whether to permit undersea mining;  attempts to reverse the flood of plastics pouring into the oceans and to curb subsidies for fishing fleets that strip the tropical seabeds bare.

Many ecologists say these debates must begin to reckon with the idea that life in the ocean is as complex and likely intelligent as life on land.

From the language of sperm whales to the problem-solving skills of fish and crabs to the dreams of octopi, here are some of the new findings supporting that idea.

Crabs ‘pay’ to avoid pain

When a British chef asked Queens University animal behaviorist Robert Elwood if crabs and lobsters experienced pain, the scientist was brought up short.

In the literature he reviewed on the question, he told The Hill, “the idea was being completely dismissed.” 

Instead, the mainstream consensus was that crabs, shrimp and lobsters drew back from unpleasant feelings only because of reflex.

Proving whether crabs felt pain — or whether any animal feels any emotion — was all but impossible, Elwood said. “Take dogs and cats: most of us would accept that they feel pain, but in fact it’s only an accumulation of evidence that makes it likely rather than that absolutely proven.”

But what he could do, he realized, was question whether crustaceans were truly only capable of short-lived reflexes — which lead to automatic responses in the moment, but generally not sustained learning.

His team worked with hermit crabs, small crustaceans that put on the abandoned shells of other creatures as they grow. When Elwood’s team used a hidden wire to give the crabs a small shock within a shell, they tended to be more likely to abandon it, even 24 hours after the initial shock — far too long, they concluded, for the response to be based on reflex. 

“You can see the animals will give up very valuable resources in order to avoid some stimuli,” Elwood said. “They will, in effect, pay to avoid those stimuli.” 

The team also found that crabs let go of shocking shells only after considering a wider array of data. Hermit crabs were less likely to abandon a good shell — however painful — than a mediocre one, and they were far less likely to trade shells at all if the water smelled of a predator than if it was clear. A painful shelter, it seemed, was better than none at all.

These findings on hermit crabs track those reached across a diverse sample of the nearly 30,000 species of decapod (ten-footed) crustaceans: species like saltwater prawns, freshwater crayfish and shore crabs, which are so distantly related that to find pain in all of them suggests the quality is widely shared, Elwood said.

“The idea that we’re cherry picking or just being completely lucky — I think it’s not sustainable,” he said.

Octopuses dream

Consciousness research often has a negativity bias. Alex Schnell, a Cambridge-trained marine biologist who hosts National Geographic’s “Secrets of the Octopus” and co-wrote the survey at the London School of Economics that ended up changing British laws on the treatment of crabs and octopuses, said that because of the urgent ethical questions surrounding seafood, “a lot of the research we were looking at was negative emotions: pain, depression, anxiety, fear. And we found compelling evidence in all groups.”

But consciousness represents far more than just the ability to suffer — and there’s growing evidence that octopuses and other “advanced” mollusks represent an example of consciousness evolving separately on the tree of life.

Schnell noted that confined octopuses in aquariums and research facilities need high amounts of cognitive stimulation — like toys and objects to manipulate. They also build rapport with their keepers, who they can identify by touching and tasting, which for octopuses are linked senses. 

A 2023 study in Nature found that the patterns on the skins of octopuses shift as they alternate between modes of sleep. This may be suggestive of dreams, the authors wrote, or at least “convergent features of complex cognition.”

Octopuses also hunt collaboratively with fish, which search the seafloor while the octopuses hunt prey through crevices in rock — while sometimes “punching” fish that get too aggressive.

Human activity broadly impacts the 650-plus different cephalopod species because cephalopods, like humans, are everywhere. “They just went into every type of ecological niche,” Schnell said.

That means that they’re at risk from a wide array of threats: The changing acidity of the oceans, which changes levels of the copper that they need in their blood; overfishing and aquaculture; and nitrate and plastic pollution. (Octopuses are known to take bits of trash back to their dens to eat and play with — or to shelter in — with unknown results.)

They are also, as a class, very sensitive to disruption: because most species only live one to two years, if something interferes with their ability to breed, they don’t get another chance. 

The annual cuttlefish mating aggregation in Whyalla, New South Wales, once the world’s largest, has collapsed by more than 90 percent in the past three decades — which may be related to brine discharges from a local desalination plant, or may have some other cause.

“Sadly, there isn’t a single cephalopod species that’s actually been listed as threatened or vulnerable,” Schnell said. “It’s not because we’re certain that they are thriving, we just don’t know enough.”

Fish pass the mirror test

In 2018, a paper on fish intelligence shook the world of animal consciousness. Scientists at the Max Planck Institute for Ornithology found that the bluestreak cleaner wrasse — a tiny reef fish that makes its living by eating dead tissue off the skins of larger fish — had passed the mirror test, a benchmark of self-awareness.

When the tiny fish were given a colored tag and put in front of a mirror, the scientists found, they tried to remove the tag. “But [they] show no response towards transparent marks, or to coloured marks in the absence of a mirror.”

The mirror test’s inventor, Gordon Gallup, wasn’t having it. A lot of people, he told Quanta magazine, were using the test “to devise ways to salvage the intellectual integrity of their favorite laboratory animals.”

So the fish were retested by a Japanese team — and passed, according to findings published in the Proceedings of the National Academy of Sciences. That just made the controversy more intense. 

“The Mirror Test is Broken,” a review in The Atlantic declared, adding that “either fish are self-aware or scientists need to rethink how they study animal cognition.” 

Brown, the Macquarie University ichthyologist, told The Hill that this response was odd. “Rather than thinking, ‘Oh well, fish smart,’ everybody thought, ‘Oh no. There’s something wrong with this test. It’s been the gold standard for 50 years, and a fish passes it, and now the test is broken.”

Brown argues that it’s “not all that surprising” that fish are potentially self-aware. They are far more closely related to humans, dolphins or corvids than octopuses or crabs are, and many live in complicated environments where intelligence — and particularly social intelligence — is an asset.

He pointed out that there are lots of examples of fish showing behaviors more familiar in birds and mammals. In pursuing prey, they perform complex mental calculus and use tools. Members of many species can learn new skills from each other, recognize family members and jockey for social position. 

And the cleaner wrasse, in particular, is known to swim after “client” fish it has accidentally bitten and rub against them, possibly to entice them to come back. (They also spend more time with regular clients.) 

But when it comes to consciousness, “there is this massive barrier, even today, about land animals versus things that live in the ocean,” he said. 

Scientists talk to whales

One principal reason consciousness research is difficult is that there is no way to truly tell if another species is conscious without their being able to tell you — and so far, humans can only understand the speech of humans.

But in the seas off the French Caribbean territory of Dominica, a team of whale scientists with the Cetacean Translation Initiative (Project CETI) are trying to decipher the communication of sperm whales. (Calling it “language,” like referring to “animal culture” in previous generations, tends to start fights.)

“We feel like we’re baby whales,” CETI founder David Gruber told The Hill. Baby sperm whales, he said, “go through a period where they’re kind of babbling, or they’re starting to [communicate], but then they’re not really doing it right — but eventually they get it.”

But the group’s main target is sperm whales, its leaders wrote in a mission plan published in iScience. The world’s largest predator, sperm whales, they wrote, have big brains, well-demonstrated cognitive abilities and complex social structures. 

They also communicate with a series of discrete clicks known as codas — a feature that, unlike the songs of humpbacks, is sufficiently similar to computer code to make it well-suited to machine analysis.

In a groundbreaking article published in Nature in May, the CETI team showed that these clicks were the basic parts of a more complicated communication structure — Gruber compared it to a “phonetic alphabet” — though the content of that structure remains opaque.

While specific features of the sperm social and communicative system lend themselves to this approach, the team’s ambitions are much grander. “We believe it’ll have relevance to many other species — like elephants,” Gruber said.

CETI cofounder Roger Payne — who discovered humpback whalesong — framed the goal of trans-species communication in urgent terms in a Time op-ed just before his death.

The ability to communicate with animals, “to ask them questions and receive answers—no matter how simple those questions and answers might turn out to be—the world might soon be moved enough to at least start the process of halting our runaway destruction of life,” Payne wrote — a destruction, he warned, that threatened to kill human society “graveyard dead.”

Gruber argues that listening to creatures far less complex than whales can signal the scale of that danger — a devastation that in his fieldwork he has seen happening at alarming rates.

“I would go to reefs that were gorgeous and healthy, and then I’d go back five, six years later, they’d just be like piles of rubble,” he said. 

It’s really distressing, he added, to see things happening on “decadal timescales that shouldn’t be happening on, you know, even 1000 year timescales.”

In a 2020 paper he co-wrote in Scientific Reports, he found that modern corals are deploying all the tricks their fossilized ancestors used to survive the cataclysm of the Cretaceous extinction, which killed off the dinosaurs. Gruber told The Hill this research was just “a different variety of listening to nature” than the whale project.

Unlike primates, he said corals have been through several mass extinctions, and the good news “is that they’re getting ready for this extinction that they’re experiencing.” 

The bad news, he said, is that “we’re not.”

— Updated June 18 at 3:20 p.m.