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Octopus DNA Seems To Confirm Scientists' Theory About A Long-standing Geological Mystery

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A study of octopus DNA may have solved an enduring mystery about when the rapidly melting West Antarctic ice sheet last collapsed, unlocking valuable information about how much future sea levels may rise in a warming climate.

The innovative research focused on the genetic history of the Turquet's octopus (Pareledone turqueti), which lives on the seafloor across the Antarctic, and what it could reveal about the geology of the region over time.

Tracing past encounters across the species' various populations suggested the most recent collapse of the ice sheet occurred more than 100,000 years ago during a period known as the Last Interglacial — something geoscientists suspected but had not been able to confirm definitively, according to the study published Thursday in the journal Science.

"This project was exciting because it offers a brand-new perspective to solve a long-standing question in the geoscience community," said lead study author Sally Lau, a postdoctoral research fellow at James Cook University in Australia.

"DNA of living animals today contains all the information about their ancestors (in the) past, so it's like a time capsule," she said.

The research team arrived at its findings by sequencing the DNA of 96 Turquet's octopuses that had been collected by institutions around the world and through fishing bycatch over the years. The oldest samples dated to the 1990s, but when sequenced, their genes provided what was essentially a detailed family tree going back millions of years.

The DNA analysis enabled researchers to understand whether different populations of Turquet's octopuses had interbred and at what point that interbreeding had happened.

"It's like doing a 23andMe on the octopus," Lau said, referring to the genetic testing company. "This information gets passed down from parents to children and grandchildren and so on."

Today, populations of Turquet's octopus in the Weddell, Amundsen and Ross seas are separated by the continent-size West Antarctic ice shelves and can't intermingle.

However, the study suggested that there was last genetic connectivity between these populations around 125,000 years ago, during the Last Interglacial, when global temperatures were similar to today's.

This finding indicated the West Antarctic ice sheet had collapsed during this time — an event that would have inundated coastal regions but opened up ice-bound areas on the seafloor that the octopuses would be able to occupy, ultimately encountering and breeding with members of Turquet's populations that were once geographically separated from one another.

"What makes the WAIS important is that it is also Antarctica's current biggest contributor to global sea level rise. A complete collapse could raise global sea levels by somewhere between 3 and 5 metres," said study author Jan Strugnell, professor and director of the Centre for Sustainable Tropical Fisheries and Aquaculture at James Cook University, in a statement. Strugnell first came up with the idea to use genomic methods to investigate whether the ice sheet had collapsed during the Last Interglacial.

"Understanding how the WAIS was configured in the recent past when global temperatures were similar to today, will help us improve future sea level rise projections," she said.

The team chose this species of octopus for the study because the animals are relatively immobile — they can only crawl along the seafloor, which means they're more likely to breed within their genetically distinct local populations. By contrast, a fast-moving marine species such as krill would have more homogenous DNA, blurring out historical genetic connections, Lau said.

Plus, the biology of the Turquet's octopus was relatively well-studied, and scientists understand its DNA mutation rate and generation time, which are crucial for accurate molecular dating, Lau added.

Previous studies involving species of crustacean and marine mollusk had detected a biological signature of ice shelf collapse with direct connectivity between the Ross and Weddell seas, Lau noted. But the new Turquet octopus study was the first with enough high-resolution data and an adequate sample size to understand whether that genetic connectivity was driven by the collapse of the ice sheet or a much more gradual movement of octopuses around its edges.

Lau said that her team's genetic approach couldn't reveal exactly when the ice sheet collapsed or how long that event took. However, with fresh octopus samples and more advanced DNA analysis techniques, it might be possible to resolve those questions in the future.

"We'd love to continue using DNA as a proxy to explore other parts of Antarctica with poorly understood climate history," she said. "We're constantly looking for new species to test these science questions."

In a commentary published alongside the study, Andrea Dutton, a professor in the department of geoscience at the University of Wisconsin-Madison, and Robert M.DeConto, a professor at the School of Earth and Sustainability at the University of Massachusetts Amherst, called the new research "pioneering."

They noted that while geological evidence had been mounting that the icy expanse of the West Antarctic ice sheet may have collapsed during the Last Interglacial period, "each study's findings have come with caveats."

Bringing an entirely different data set to bear on this urgent issue "posed some intriguing questions, including whether this history will be repeated, given Earth's current temperature trajectory," they added.

Using octopus genomics was "an innovative and exciting way" to address an important question about historical climate change, said Douglas Crawford, a professor of marine biology and ecology at the University of Miami who wasn't involved in the research.

"This is a careful study with sufficient sample size and carefully vetted set of genetic markers," he added.

"It takes a challenging hypothesis and uses a totally independent data set that (ultimately) supports WAIS collapsed," he said via email.

Octopus DNA Reveals Antarctic Ice Sheet Is Closer To Collapse Than Previously Thought: "Unstable House Of Cards"

Scientists investigating how Antarctica's ice sheets retreated in the deep past have turned to an innovative approach: studying the genes of octopuses that live in its chilly waters.

A new analysis published Thursday in Science finds that geographically-isolated populations of the eight-limbed sea creatures mated freely around 125,000 years ago, signaling an ice-free corridor during a period when global temperatures were similar to today.

The findings suggest the West Antarctic Ice Sheet (WAIS) is closer to collapse than previously thought, threatening 3.3-5 meters of long term sea level rise if the world is unable to hold human-caused warming to the 1.5 degrees Celsius target of the Paris Agreement, said the authors.

Lead author Sally Lau of James Cook University in Australia told AFP that as an evolutionary biologist focused on marine invertebrates, "I understand and then apply DNA and biology as a proxy of changes to Antarctica in the past."

Turquet's octopus made an ideal candidate for studying WAIS, she said, because the species is found all around the continent and fundamental information about it has already been answered by science, such as its 12-year-lifespan, and the fact it emerged some four million years ago.

About half-a-foot (15 centimeters) long excluding the arms and weighing around 1.3 pounds (600 grams), they lay relatively few, but large eggs on the bottom of the seafloor. This means parents must put significant effort into ensuring their offspring hatch -- a lifestyle that prevents them traveling too far away.

They are also limited by circular sea currents, or gyres, in some of their modern habitats.

By sequencing the DNA across genomes of 96 samples that were generally collected inadvertently as fishing bycatch and then left in museum storage over the course of 33 years, Lau and colleagues found evidence of trans-West Antarctic seaways that once connected the Weddell, Amundsen and Ross seas.

The history of genetic mixing indicated WAIS collapsed at two separate points -- first in the mid-Pliocene, 3-3.5 million years ago, which scientists were already confident about, and the last time in a period called the Last Interglacial, a warm spell from 129,000 to 116,000 years ago.

"This was the last time the planet was around 1.5 degrees warmer than pre-industrial levels," said Lau. Human activity, primarily burning fossil fuels, has so far raised global temperatures by 1.2C compared to the late 1700s.

"Tipping point of future WAIS collapse is close"

There were a handful of studies prior to the new Science paper that also suggested WAIS collapsed some time in the past, but they were far from conclusive because of the comparatively lower resolution genetic and geological data.

"This study provides empirical evidence indicating that the WAIS collapsed when the global mean temperature was similar to that of today, suggesting that the tipping point of future WAIS collapse is close," the authors wrote.

Sea level rise of 3.3 meters would drastically alter the world map as we know it, submerging low-lying coastal areas everywhere.

Writing in an accompanying commentary piece, Andrea Dutton of the University of Wisconsin-Madison and Robert DeConto of the University of Massachusetts, Amherst described the new research as "pioneering," adding it posed intriguing questions about whether ancient history will be repeated.

They flagged however that several key questions remained unanswered -- such as whether the past ice sheet collapse was caused by rising temperatures alone, or whether other variables like changing ocean currents and complex interactions between ice and solid Earth were also at play.

It's also not clear whether the sea level rise would be drawn out over millennia or occur in more rapid jumps.

But uncertainties such as these can't be an excuse for inaction against climate change "and this latest piece of evidence from octopus DNA stacks one more card on an already unstable house of cards," they wrote.

All-seeing Skin, Detachable Butts And Zombies: Animal Oddities Of 2023

The animal kingdom has no shortage of weird and wonderful surprises, and this year biologists gave us some real treats to talk about at the dinner table. All walks of life, from microscopic bacteria to huge cetaceans have remarkable, varied adaptations, and the more we know about how animals interact with their environment, the better our chances will be of preventing extinction. And some adaptations also proved to be very amusing …

Octopus sleep like us, cuttlefish see with their skin

Scientists discover a fascinating new aspect of octopus cognition

Researchers from the Okinawa Institute of Science and Technology (OIST) and the University of Washington examined the brain activity and patterning behavior of the Octopus laqueus and found that it experienced an active stage of sleep similar to rapid eye movement (REM) slumber. What's more, the animal's behavior during this time suggested that, like humans in REM sleep, an octopus might be dreaming, providing new insight into the animal's cognitive capabilities.

Meanwhile, in what was a big month for both the Japanese university and cephalopods, OIST and Max Planck Institute for Brain Research scientists unearthed fascinating new findings as to how the cuttlefish can precisely control and color-correct its camouflaging patterns, showing much greater brain function than previously thought.

Bats with huge heart-shaped penises work with what they've got

The male serotine bat has found a novel way to ensure mating success

Alona Shulenko

Researchers at the University of Lausanne, Switzerland, made some curious discoveries about a group of bats living in a church attic in the Netherlands. The bats had been captured on camera engaging in marathon sex sessions, which seemed a little odd. On closer inspection (all in the name of science, of course), they found that the male serotine bat (Eptesicus serotinus) was sporting a heart-shaped penis that, when erect, measured a fifth of the length of his 2.75-inch (7-cm) body and seven times longer than his partner's vagina. Because of this, the scientists discovered, the bats were having non-penetrative sex, using their penis like an arm to push aside the female's tail to mate in a way similar to cloaca-contact sex in the bird world. It's the first-ever account of superficial-contact mating among mammals. (Click through to see photos of the bat's now world-famous features.)

This beetle, however, has a bottle-opener-shaped penis

Scientists are yet to confirm just why this penis shape exists in the species

University of Copenhagen

Not to be outdone by bats, this European beetle was discovered to have a penis shaped uncannily like a bottle opener. The University of Copenhagen researchers that made this discovery on the newly found species of rove beetle then, fittingly, named it Loncovilius carlsbergi, paying tribute to Denmark's famous beer company Carlsberg. At the time of publication, the researchers were working on producing a bottle opener based on the beetle's penis, to raise awareness of insects – which are the most populous animal on the planet, yet also the most disregarded when it comes to conservation.

Female frog plays dead to avoid unappealing males

Researchers discover the female frog's sneaky move to get males off her back

Adaptations for selective mating is common in female species, and scientists from the Konrad Lorenz Institute of Ethology, Vienna, discovered a particularly dramatic one this year. When bombarded with attention during 'explosive breeding' frenzies, the female European common frog (Ranat emporaria) will fake her own death to avoid mating with an undesirable male. Scientists believe the strategy evolved from tumbling in water, which can drown male and female frogs. So this act of playing dead is both a convincing and an energy-conserving one.

A group of ants were also found to be good actors (mostly)

This group act by the ants was a small but significant finding

In a first, scientists observed not one but a group of ants simultaneously faking their own death. While single ants playing dead have been recorded before, it's never been seen in a group of animals. The scene was discovered by accident, when University of South Australia researchers were investigating nesting boxes for native animals on Kangaroo Island. At first, the scientists thought the ants had died in the boxes, until one Polyrhachis femorata ant gave the grift away and was seen moving. They witnessed this curious behavior throughout the fieldwork, with some ants instantly triggered and others taking longer to get into character.

DNA distribution reveals sea stars to be all head, not arms

Scientists discover the sea star's 'arms' actually have 'head' genes right down to their ends

Laurent Formery

Upending what biologists know about sea stars, commonly known as starfish, researchers from Chan Zuckerberg Biohub San Francisco, working with labs at Stanford University and the University of California Berkeley, found that it has genetic markers for a head, yet none that code for a torso or tail. The genetic signatures for the head were localized in the middle of each of the animal's 'arms', leading scientists to believe the sea star is, in fact, more of "a head crawling along the seafloor."

Snake is seen reducing its own species biodiversity

It's a snake-eat-snake world in Far North Queensland Nick Stock/Australian Wildlife Conservancy

While this kind of cannibalism is not entirely unusual in the world of snakes, recording it is. Nick Stock from Piccaninny Plains Wildlife Sanctuary in Australia (where else), photographed a large black-headed python enjoying a sizeable meal of another black-headed python. Despite the python's usual behaviors of constricting prey fatally before eating, this smaller snake was indeed consumed while it was still alive. The non-venomous, constricting python (Aspidites melanocephalus) is known to eat other reptiles and will opportunistically take a juvenile relative if it can.

Genetics reveal just how beetles drink with their butts

This Colorado leaf beetle can go through its entire life drinking water only through its rectum

Scientists uncover the genetic mechanism that makes it easy for beetles to extract scarce water from their environment and absorb it through their rectum. The researchers from the University of Copenhagen, the University of Edinburgh and the University of Glasgow discovered that the red flour beetle (Tribolium castaneum) had one gene expressed 60 times more in the rectum than anywhere else in the animal's body, and it was localized to a unique group of cells, key to this butt drinking. Because the beetle is genetically similar to other species such as the Colorado leaf beetle, scientists believe muting this genetic mechanism could make environments such as farmed grain crops uninhabitable for them.

Prolific pee-flicking bug uses physics to fling urine around

The glassy-winged sharpshooter in the process of peeing

Georgia Tech

Scientists at Georgia Tech used high-speed video and microscopy to uncover how the glassy-winged sharpshooter (Homalodisca vitripennis), which urinates around 300 times its own bodyweight every day, manages to flick pee such great distances. And it's epic. The bug is adorned with an anal appendage dubbed a "butt flicker," and this rear-end pinball paddles flicks drops of pee at 40 G's, using physics never before seen in nature. The scientists believe that while it's fun to watch (check out the video in the link), this natural adaptation also has practical bio-inspired applications.

Meanwhile, this bug detaches its butt to send it off for mating

This marine worm has a novel tail-end adaptation for reproduction

Because we couldn't get enough insect butt discoveries in 2023: University of Tokyo researchers unraveled the genetic mystery behind how the Japanese green syllid worm (Megasyllis nipponica) grows a 'mini-me' at its rear end, which it then deploys so it can swim off on its own in search of a similar autonomous tail of the opposite sex to spawn with. The worm, meanwhile, will then grow another, to deploy for mating once more.

Scientists find bug that can turn 'zombie mode' on and off in ants

Scientists uncover advanced behaviors in pathogenic flatworm and its host ant

In another first, University of Copenhagen scientists discovered how one cunning pathogenic flatworm can switch 'zombie mode' on and off, engaging in an intermittent hostile takeover when it best suits them. The parasitic lancet liver fluke (Dicrocoelium dendriticum), takes over the brains of European wood ants when the temperature is optimal, steering the ant up a blade of grass and waiting in the hope of feeding cows or sheep – the flatworm's final host – grazing past. If it fails and the temperature changes, the ant regains its faculties … until the next takeover, that is.

Parasite makes 'zombie shrimp' stand out from the crowd

Two amphipods – the top image showing one their natural color, while the bottom image shows the color change they undergo after infection by a parasitic worm

David Johnson

Scientists at Brown University discovered how the parasite Levinseniella byrdi, which can only reproduce in the guts of certain marsh bird species, hacks the genome of its amphipod host to change its behavior and color in order to make it easy pickings for the host bird it needs. Using RNA sequencing, the scientists found that the parasitic worms activate genes that involve pigmentation, interfere with their ability to detect external stimuli, and suppress multiple genes involved in immune responses, which would otherwise fight off the parasite. Not so great for the formerly, elusive, camouflaged amphipod, but excellent for the parasite (and not too bad for the bird, either).

Researchers capture bird's insane 700-mile typhoon joyride

The streaked shearwater may be the first of his kind to join the three-mile-high club

Thanks to GPS bio-loggers attached to 14 adult streaked shearwater (Calonectris leucomelas) seabirds, Tohoku University scientists found that one bold male threw caution to the wind, flying above Typhoon Faxai as the storm pummeled southeastern Japan. It was the start of an 11-hour, 1,146-km (712-mile) crazy journey that took the bird 4.5 km (15,000 ft) higher than normal, at three times its usual speed. The bird lived and the researchers gained incredible new insight into seabird migration patterns and how they may be adapting to more frequent extreme weather events.

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