‘Not so alien’: biologist busts myths and explores enigma of the octopus

This story was originally published by The Guardian and appears here as part of the Climate Desk collaboration

Sat on a dock, a bucket was filled with what appeared to be the ingredients for that night’s dinner — a collection of freshly severed octopus arms.

But then, it began.

“As we were standing there for some time chatting, each arm began to crawl out of the bucket,” says David Scheel, a professor of marine biology at Alaska Pacific University.

As the movement continued, sucker by sucker, the tips of the tentacles reached over the rim. The dead was walking.

It sounds like the stuff of nightmares, but for Scheel it was just another example of the fascinating biology of the ocean’s most enigmatic inhabitants.

Whether immortalized as giant monsters, fetishized in tentacle pornography or celebrated as psychic football pundits, octopuses have long fascinated humans.

Their appearance is undoubtedly captivating. As Victor Hugo noted in his description of an octopus attack: when swimming the animal resembles a closed umbrella without a handle.

But their anatomy is no less intriguing. The brain is located between the eyes, while what looks like a bulbous head is actually the mantle, containing the stomach and anus among other structures. And octopuses not only boast eight arms — which can regrow if severed — but three hearts. And the animals cannot see colour, at least in the way we do, but they can see the polarization of light.

The crawling tentacles highlight another astonishing feature.

“The movement of the suckers relative to each other is not co-ordinated by the central brain, as we might imagine in a human, for example,” says Scheel. “Instead, it’s co-ordinated within each arm.”

As a result, the suckers can work with their neighbours, even when severed from the rest of the animal, provided the tissues still have enough oxygen (and so have not yet died).

The default motion is for items to be moved along the chain of suckers towards the animal’s mouth.

“If you do that against an immobile surface, the octopus arm will crawl tip first away from the mouth, as each bit of substrate below it is passed towards the mouth,” says Scheel.

The upshot is that, in a bucket, the severed arms move as if attempting an escape.

An expert in octopus behaviour, Scheel is no stranger to their peculiarities. But in his new book, Many Things Under a Rock, he hopes to offer a fresh perspective on what are often considered otherworldly animals.

“Maybe the biggest misconception about them is that they’re very alien and very different from us,” he says. “And I think one of the messages I wanted to get across in the book is that all of life, all of animal life in particular, shares a set of universal goals.” Among them, he says, animals are driven to seek food, shelter and a mate.

Indeed with their big eyes, curious nature and famously moody characters — one recent study found they deliberately throw rubbish at other octopuses — the creatures can seem strangely human.

Yet commonalities between us and them are not surprising: as Scheel notes, like other animals, we share a deep evolutionary history.

“We’ve sort of villainized anthropomorphizing animals on the grounds that we shouldn’t assume that the human experience relates directly to the animal experience. And that’s fair,” he says. “But we also shouldn’t assume that it doesn’t — the two are not completely divorced from one another.”

But octopuses do some things very differently. Take sex: while humans get up close and personal, octopuses do it at arm’s-length.

“In males, the third right arm is modified for mating,” says Scheel, adding that the male uses this arm to pass sperm packets to the female’s mantle cavity.

It can be a dangerous act.

“The females sometimes will attack and kill the males. Octopuses can be cannibalistic, and particularly when it’s a larger female and a smaller male, the male’s at a considerable risk,” says Scheel.

Octopuses are also masters of disguise.

“Moving across the reef flats, the day octopus changes on average three times per minute when mobile,” Scheel writes, describing how the creatures can change colour to blend in, as well as alter their posture, body patterns and textures.

The shift may appear magical, but it is a clever trick.

“They do it all by using tiny muscles in the skin that control chromatophores, which are cells that function basically like little bags of pigment, and they can either spread those little bags out, so all the pigment is visible, or allow the bags to hang closed, so that what’s under those chromatophores can actually be seen,” says Scheel, adding that under the chromatophores are layers of skin that can reflect or diffuse light, aiding the creature’s camouflage.

Many Things Under a Rock also discloses the discovery that fish and octopuses can co-operate when foraging, and the revelation that octopuses may dream.

And while the Kraken may be a myth, there is no shortage of alarming encounters, from native legends to Scheel’s personal experience of Calamity, the captive octopus who had a penchant for squirting water from her tank and attempting to pull aquarists in.

Yet Scheel’s book, with its quirky tales and scientific insights, comes as our relationship with octopuses is in flux.

Last year, the U.K. established the Animal Welfare (Sentience) Act 2022, with octopuses among the animals covered.

However, despite growing recognition that octopuses are intelligent and can feel pain, plans are afoot for octopus farming.

For Scheel, it is clear that octopuses have some level of inner experience and awareness of themselves. But when it comes to rights, he says, the question is not so much about how octopuses act, but how humans behave.

“We [are] continually deciding whether we want to be the kind of society that views nature as property, as commodities,” he says. “Or be one that treats nature as its own entity, an entity in which we’re immersed, something with its own ends and goals, an entity that we share with myriads of individuals and many, many species who can live better or worse lives.”