On the 3rd of November 2022, a research ship pulled away from the coast of Hainan Island in southern China, carrying what might be the strangest cargo in the history of ocean science.
A cow, not a living one, it had been processed at a certified slaughterhouse.
Its organs had been removed, and its body had been cut cleanly into two halves.
Nose to tail, it measured 2.7 meters.
The scientists on board were going to sink it.
Not a little way.
1,629 m down.
Stack five of the Gold Coast’s Q1 towers on top of one another, and you still would not reach the bottom.
Down to a stretch of seafloor where sunlight has never once arrived.
Next to the cow, they set a steel frame carrying a camera and a light.
They plugged it into a power cable that already ran along the seabed.
Then they left it there in the dark and waited.
The first visitor showed up the very next day.
By the day after that, something down there had grabbed the carcass and dragged the whole thing clean out of the camera’s view.
For roughly 13 hours, the footage showed almost nothing.
Darkness, clouds of churned up mud, and every so often, the side of something very large sliding past the lens.
When the team sent a robot down to drag the cow back into position, one of the animals came straight back, right there in front of the robot, and kept eating.
Now, here is the part that makes this story so strange.
Nobody on that ship had gone out looking for a predator.
They were trying to stage a funeral.
The funeral of a whale.
And the trail that leads away from that cow runs a very long way.
It runs to a trench off the coast of Western Australia, where whales have been sinking to the bottom for more than 5 million years.
To a worm with no mouth and no stomach.
First recognized by a museum scientist in Adelaide whose males are so small they live inside the female.
To an old Australian Navy frigot that now sits in a dry dock in Brisbane.
And it runs to a question that matters to anyone who has ever watched a humpback breach off an Australian headland.
What happens in the dark when a whale dies?
And what did we wipe out down there without ever seeing it?
As for the animals that found the cow, by the end of this, you will understand why even the scientists who identified them are not completely sure they were strangers at all.
I’m Edmund Hail.
Let’s go down.
To understand why anyone would sink a cow, you first have to understand how hungry the deep sea is.
Picture the floor of the ocean 2 or 3 km down.
It is cold.
It is black.
The pressure would crush a car.
And almost nothing grows there.
There is no light, so there are no plants.
Nearly everything that lives on the deep sea floor depends on food that falls from above.
Most of that food arrives as something called marine snow.
Flakes of dead plankton, scraps of feces, shreds of mucus.
All of it drifting down from the bright surface slowly for weeks getting picked over by everything it passes on the way.
By the time it reaches the bottom, there is very little left.
So the deep sea is a desert, not of sand, but of calories.
And then every so often something enormous happens.
A whale dies.
And when a great whale dies out at sea, far more often than not, it does not wash ashore.
It sinks down through the sunlit layer, down through the twilight zone, down into the black, and they land.
A single large whale can deliver to one small patch of seafloor as much food as that patch would normally receive over hundreds, even thousands of years.
Scientists have a name for it, a whale fall.
And it is not just a meal.
It is the beginning of an entire world.
The first to arrive are the scavengers, hagfish, sleeper sharks, crabs, enormous crustaceans called amphipods.
They follow the scent through the water and begin stripping the flesh.
That stage can last for months.
Next come the opportunists.
Worms, snails, and small crustaceans move into the sediment around the skeleton, feeding on the fat and tissue that has soaked into the mud.
Then comes the strangest stage of all.
Whale bones are packed with oil.
As bacteria break that oil down, they release sulfur compounds.
And in that chemistry, a community grows up that feeds not on sunlight, but on chemical energy, a little like the life around volcanic vents on the ocean floor.
A big whale skeleton can keep that going for decades.
So, if you are a scientist who wants to see the deep sea at its most alive, a whale fall is the single best place on Earth to stand.
There is just one problem.
You almost never find one.
The first modern whale fall was found by complete accident.
In November 1987, a team that included the American oceanographer Craig Smith was diving in the submersible Alvin, more than a kilometer deep off Southern California.
They were looking for something else entirely.
And there in the headlights lay the skeleton of a blue whale around 21 m long.
The bones were coated in bacterial mats and covered in clams and worms that at the time scientists associated with volcanic vents.
Nobody expected to find that kind of life on a dead animal.
That one accident turned whale falls into a field of science.
But nearly four decades later, the number of natural modern whale falls that anyone has actually found and studied is still tiny.
When Chinese researchers found their first one in 2020, they described it as one of fewer than 50 known anywhere in the world.
Fewer than 50 in the whole ocean.
That first Chinese discovery is part of our story, too.
In March of 2020, the research ship Tanuo1 carried a crude submersible on a series of dives into the South China Sea.
On one of those dives at around 1,600 m, the crew saw a small whale carcass about 3 m long lying on the sea floor.
Fish were tearing at its tail.
It was fresh.
It was still in that very first stage.
The scavenger stage.
One of the scientists on that expedition was Shia Wei, a marine scientist at Sunyatsen University.
And that sighting pointed to a very simple, very frustrating idea.
What if you could make that happen on purpose?
Because a natural whale fall is a gift you cannot order.
You cannot ask a whale to die on Tuesday in the right place in front of your camera.
So the researchers began to build their own.
The idea of an artificial whale fall was not new.
For years, scientists elsewhere had been sinking dolphins, porpuses, and the odd stranded whale to watch what happened.
But smaller carcasses vanish too quickly.
The scavengers finish them before the later stages ever begin.
And real whales are almost impossible to get, move, and sink where you want them.
So the team in the South China Sea turns the largest animal they could buy, legally prepare, load onto a ship, and anchor to the seafloor, the humble cow.
In one earlier experiment published in 2023, they sank three cows at three different depths on the flanks of an underwater mountain called Jeong Nan Seamount in the middle of the South China Sea.
The shallowest was 655 m down, the deepest more than 3,400.
Those cows did exactly what a whale would do.
They drew in scavengers.
They fed the mud.
And on and around them, the scientists found worms belonging to a little known group, including three species that turned out to be completely new to science.
A cow, it turned out, is a very good whale.
Which brings us back to that ship off Hainan in November 2022.
The site was chosen with care.
Off the southeast coast of the island, the seabed tips over a steep slope into deep water not far from land.
And on that slope, the Institute of Acoustics of the Chinese Academy of Sciences runs a sealoor observation network with a power cable laid along the bottom.
That cable was the secret weapon.
Most deep sea cameras run on batteries.
They record for a few hours and then they die.
But this one could be wired straight into Maine’s power on the seabed.
It could watch and keep watching for weeks.
The cow went down beside a metal frame.
The camera sat about 2 m from the meat.
A remotely operated vehicle with two robotic arms followed it down to check everything was where it should be.
And the plan was the classic whalefall plan.
Watch who comes, watch who eats, watch the community change.
Within a day, that plan started falling apart.
Before we find out who came to dinner, I want to take you somewhere much closer to home.
Because while that cow was being stripped in the South China Sea, the largest whale fall site ever recorded was waiting to be found in the deep water of Western Australia.
In February 1960, an Australian Navy ship called HMAS Diamantina was carrying out oceanographic surveys in the Indian Ocean west of Cape Leuen.
She was an old riverclass frigot built in Queensland during the Second World War.
She had seen action off Bogenville.
A Japanese garrison had surrendered aboard her.
Now she was a survey ship out of Fremantle measuring the shape of a sea floor.
And off the southwest corner of the continent, her soundings revealed part of a gash in the ocean floor.
So deep that for decades it was listed as the deepest point in the entire Indian Ocean.
That title turned out to be wrong.
When the trench was finally mapped in detail in 2019, its deepest point came in at a little over 7,000 m.
Still one of the deepest places in the Indian Ocean, but not quite the deepest.
The trench and the long scar of seafloor it sits in still carry the ship’s name, the Diamantina fracture zone.
And the ship herself is still with us.
She is the last surviving ship of her class anywhere.
And she sits in the old dry dock at the Queensland Maritime Museum in Brisbane where you can walk her decks today.
For more than 60 years after Diamantina found it, almost nobody went to the bottom of that trench.
Then between February and March of 2023, a Chinese team brought down the crude submersible Fendu, a name that means stver.
On one dive deep in the zone, the crew came across the bones of a whale.
That alone would have been worth the trip.
But the scientists did something clever.
Instead of celebrating and moving on, they went back down again and again.
Dozens of dives along roughly 1,200 km of seafloor at depths between about 4,600 and 7,000 m.
And the bones did not stop.
They documented 476 fossil whale sites, skulls, vertebrae, ribs.
In places, the remains reached a density of more than 700 individuals per square kilometer.
And among the fossils, they found five active whale falls.
Recent carcasses still feeding living communities.
One of them, a cluster of three beaked whale vertebrae, sat at 6,789 m.
That is the deepest active whale fall ever recorded.
It pushed the known depth limit of these ecosystems down by more than 2 1/2 kilometers in a single expedition.
When the team dated the fossil bones, the oldest went back at least 5.3 million years.
Among them was a beaked whale that had never been described before.
It has now been named Terositus Diamantine after the ship and the trench.
The researchers led by Pang Shaoong at the Institute of Deep Sea Science and Engineering published their findings in the journal Nature in June of this year.
They called the place a whale necropolis and their estimate of what lies down there across the whole zone is hard to take in.
More than 10 million whale remains.
So why here?
Why would one trench off Western Australia gather whale bones for 5 million years?
The answer seems to be the shape of the seafloor itself.
The Diamondina zone is a maze of steep slopes and deep troughs shaped a little like a giant V.
When a carcass lands on one of those slopes, gravity and currents can slowly nudge it downhill into the low ground.
Over enormous spans of time, the trench works like a funnel.
Add to that the whales that live above it.
These waters are home to several species of deep diving beaked whales, some of the most mysterious mammals on the planet.
And the bones may matter well beyond biology.
The team estimated how much carbon those 10 million or so carcasses could have carried into the deep.
Their answer was around 6.7 million tons.
Roughly the same amount that marine snow would deliver to that seafloor in 4,700 years.
Every one of those whales, in other words, was a small piece of the atmosphere locked away at the bottom of the sea.
But here is the catch, and it is a big one.
A graveyard can tell you that whales died there.
It can tell you what lived on the bones in the end.
It cannot show you the beginning.
It cannot show you who arrives in the first few hours when the carcass is fresh and the smell is spreading through the dark.
For that, you need a camera already on the seafloor, already switched on when the meat lands.
You need a cow.
And there is one more creature I need to introduce before we go back to Hainan.
Because when you sink a carcass and leave it long enough, sooner or later, this is what moves in.
In February 2002, a team from the Mterrey Bay Aquarium Research Institute in California, led by the biologist Robert Brian Hook, sent a robot nearly 3 km down into a submarine canyon.
They were looking for deep sea clams.
What they found was the skeleton of a gray whale.
And growing out of its bones like a lawn of tiny red flowers was something none of them could identify.
So they sent samples to a man named Greg Rouse.
Rouse was Australian.
He had studied at the University of Queensland and the University of Sydney.
And at the time he was a curator at the South Australian Museum in Adelaide.
He was one of the world’s leading experts on marine worms and he confirmed what the Californians suspected.
These animals were entirely new to science.
They were worms, but they had no mouth, no gut, no stomach at all.
Instead, the females sent rootlike tissue down into the whale bone.
Living inside those roots were bacteria that could break down the fats and proteins locked in the bone.
The worm drilled, the bacteria digested, and together they fed.
The scientists named the new genus oidax, Latin for bone devourer.
Then came the detail that made Rouse certain these were worms at all.
Every large worm they examined was female.
The males were there too, but they were microscopic.
They looked almost like lavi and they lived inside the jellyike tube that surrounds each female.
Sometimes dozens of them at once.
A harim of tiny males living inside their partner on the bones of a dead whale in the dark.
Within a year of that discovery, the same kind of worm was turning up on whale carcasses that scientists had deliberately sunk off Sweden and off Japan.
Since then, bone eating worms have been found across much of the world.
They have even been found in the Diamond Tina whale graveyard.
And in 2017, Australia finally got a whale fall of its own.
The CSRO research vessel investigator was surveying the deep sea floor off the east coast, dragging a troll along the bottom when the net came up holding something nobody had planned to catch.
Pieces of a whale fall from about a thousand m down.
When researchers, including scientists at the Australian Museum in Sydney, worked through the worms living on those remains, they described nine species new to science.
They were the first whalefall worms ever described from Australian waters.
Nine new species from one accidental hall, which tells you how little we have seen.
And it raises the question that will come back to haunt us later.
If one dead whale can carry nine species nobody had ever named, what happened to all the species that depended on whales during the years when we were killing them?
Hold that thought because it is time to go back down to the cow.
The camera off Hanan started recording on the 3rd of November.
Just after midday on the 4th, the first animal glided into the light.
It patrolled around the carcass.
It fed.
It left.
A few minutes later, it came back again.
That evening, a second one arrived.
Then, close to midnight, a third, which circled twice before it finally committed and began to feed.
These were big animals, thick, rounded bodies, short, blunt snouts, small eyes.
They moved slowly, almost lazily, as if they had all the time in the world.
In the early hours of the 5th of November, the fourth one arrived.
And the fourth one was huge.
The scientists later estimated it at around 5.1 m long, nearly twice the length of the cow it was eating.
It fed for well over an hour.
And then somewhere around 4 in the morning, it did what no one had planned for.
It took hold of the carcass and pulled it right out of the camera’s view.
For the next 13 hours or so, the camera was watching an empty patch of seafloor.
Twice, plumes of sediment billowed through the frame, almost certainly kicked up by something feeding just out of sight.
Once an animal flashed through the light and was gone up on the surface, the team decided they had to intervene.
They sent the remotely operated vehicle back down to find the cow and haul it back into position.
And while the robot was doing that, one of the animals swam in and started feeding again right in front of it.
So for a short while, the deep floor of the South China Sea hosted something truly ridiculous.
A robot and a wild predator, both wrestling over half a cow.
The robot won.
The cow went back in place.
And that evening, two more animals arrived.
One immediately after the other.
By the time the experiment ended on the 21st of November, the team had a problem nobody expects in a deep sea study.
Too many big animals to keep track of.
So, they did what wildlife biologists do with whales and wolves.
They started telling the individuals apart.
One had a long horizontal scratch running from its gills to its first dorsal fin.
Another had a dark round spot near its pelvic fins.
One was covered in black patches.
One had a cluster of scars around its eye.
[snorts] One carried parasites on its head and tail.
One had an injured petrol fin.
Eight animals in all.
To measure them, the scientists used the only ruler they had down there, the cow.
They knew it was 2.7 m long.
So they divided that length into 100 equal segments on their screen and counted how many segments each animal stretched across when its snout was touching the meat.
The smallest came in at around 1.3 m.
The largest that 5 m giant.
And then came the moment of identification.
They were sharks.
Pacific sleeper sharks.
The paper reporting them led by Han Tan and the oceanographer Yin Kadong at Sununyat Sen University was published in the journal Animals in 2024.
A second paper on the sharks feeding behavior followed in 2025.
And it was not the species that shocked them.
It was the address.
Pacific sleeper sharks are cold water animals of the North Pacific, Japan, Russia, the Bearing Sea, Alaska, down the coast of North America.
Before this, the southernmost place one had ever been caught on that side of the Pacific was off the east coast of Taiwan.
No one had ever recorded a Pacific sleeper shark in the South China Sea.
Not one.
Now, on a single camera at a single cow, there were eight.
The researchers calculated that the record pushed the known range of the species more than 1,200 km to the west and more than 700 km further south.
And the scientists were careful about what that meant.
Their point was not that these sharks had suddenly moved in.
It may simply be that nobody had ever looked.
The team did not rule out that a changing ocean has played some part, but the simplest explanation is the one about us.
Deep sea fishing surveys in the South China Sea rarely work below about 1,000 m.
These sharks were feeding at more than 1,600.
They could have been there all along, cruising through a world no net and no camera had reached.
Eight sharks of different sizes all in one place also suggested something else.
The population down there is probably much larger than eight.
Then came two details that turned a range record into a mystery.
The first was the way they at.
Pacific sleeper sharks are thought of as loners.
Records of more than one together are extremely rare.
Yet at the cow, the last two sharks arrived one immediately after the other and appeared to take turns.
One fed, then made way, and the next moved in.
The researchers described it as Q-ike feeding.
Han Tian suggested the order might be set by how competitive each individual was.
Bigger, boulder sharks pushing to the front, others waiting.
A kind of deep sea etiquette that stops large predators from fighting over a rare meal.
And the team noted that the sheer aggression of the feeding hinted at something else, that the deep South China Sea may hold more food falling from above than anyone had assumed.
The second detail is the one that still has no answer.
There was no way to examine the sharks up close, but based on the shape of their pelvic fins in the footage, every one of the eight appeared to be female.
Every single one.
The scientists pointed out that another giant deep water shark, the mega mouth, also shows a strong female bias in this region.
And they raised the possibility that this corner of the South China Sea might be serving as a nursery ground for large sharks.
If that is right, the cow did not just reveal a new population.
It may have stumbled into a maternity ward.
Nobody yet knows.
The species is listed as nearthreatened and within its known range, its numbers are thought to have fallen by around a fifth to more than a quarter.
Scientists still cannot say with confidence how fast these sharks grow, when they mature, or how long they live.
Which brings us to the question I promised you at the very beginning.
Were these sharks really strangers?
For most of the last century, scientists recognized three giant sleeper sharks.
The Greenland shark in the North Atlantic, the Pacific sleeper shark in the North Pacific, and a third living throughout the cold waters of the Southern Hemisphere.
That southern animal has a deeply Australian story.
During Douglas Morrison’s Australasian Antarctic Expedition, a large shark washed up on Mcquary Island, the subant Antarctic island that belongs to Tasmania.
In 1913, someone on the expedition made a sketch of it.
That sketch became the basis for the southern sleeper shark, a species later formerly named by the Australian ichthyologist Gilbert Whitley.
The southern sleeper shark has since been recorded in the deep waters of southern Australia, New Zealand, and South America.
But when geneticists started reading the DNA of these animals, something did not add up.
In 2022, a team led by Laura Tim at the United States Fisheries Agency compared genetic material from sleeper sharks across their range.
The Greenland shark came out clearly distinct.
But the Pacific sleeper shark and the southern sleeper shark did not.
The southern samples, only a couple of them, sat right in among the Pacific ones.
The authors described their results as the strongest molecular evidence yet that the two may be one and the same species.
Not everyone agrees.
Some researchers still keep the southern form separate, pointing to differences in fins, teeth, and vertebrae.
The argument is not settled.
But think about what it would mean if Tim and her colleagues are right.
The shark that dragged a cow out of camera range of southern China would be the same species that washed up on Mcquaryy Island a century ago.
The same species living in the deep of Tasmania and southern Australia.
Not a visitor from Alaska.
Possibly one long continuous population stretched along the deep slopes of the Pacific from the Bearing Sea to the Southern Ocean with Australia on its doorstep.
And Australian science has just pushed that story further south than anyone thought possible.
In January 2025, a baited camera dropped by the Mindaroo UWA Deep Sea Research Center based at the University of Western Australia in Perth was sitting on the seafloor off the South Shetland Islands near the tip of the Antarctic Peninsula.
The researchers went through hundreds of hours of footage and at 490 m in water of just over 1° C, a large shark drifted into the light.
A sleeper shark, most likely a southern sleeper shark, a female somewhere between 3 and 4 m long.
Before that moment, there was a general rule in marine biology.
There are no sharks in Antarctica.
The cent’s founding director, Alan Jameson, admitted his team had gone down there, not expecting to see sharks at all.
It was the first time any shark had been filmed in Antarctic waters.
The animal was cruising in the warmest band of water available, a layer trapped between colder, saltier water below and icy melt water above.
Jameson suspects there is a small settled population living in that band simply unseen because for most of the year nobody is down there looking.
That is the same lesson the cow taught.
These animals were not missing.
We were.
And there is one last door the cow opens.
The one I asked you to hold on to.
Remember those worms that live only on whale bones?
The bone devourers?
The worms from the first Australian whale fall?
Scientists believe more than 100 species may be whale fall specialists.
Animals that have only ever been found or found in real numbers on the bodies of dead whales.
Now, think about what happened to the whales.
Industrial whaling cut the world’s great whale populations by at least 2/3 and in some cases by far more.
And the factory ships did not just kill whales.
They processed the whole carcass.
Those bodies never sank.
They never became whale falls at all.
Craig Smith, the same scientist who stumbled on that first blue whale skeleton in 1987, has spent years asking what that did to the deep.
In 2019, he and his colleagues Joe Roman and JB Nation published a model of whale fall habitat.
Their conclusion was stark.
Whaling may have driven some whale fall specialists extinct before anyone ever saw them.
And because the biggest whales provide the longest lasting falls, losing the giants mattered even more than losing the numbers.
Their model also carried a warning aimed squarely at our side of the world.
Whales were depleted more recently in the southern hemisphere, so the deep sea here may still carry what ecologists call an extinction debt.
Species that are still hanging on but are doomed unless the whales come back in large enough numbers and grow large enough over the next few decades.
Which brings this story home.
In 1952, the largest landbased whaling station in the southern hemisphere opened at Tangaluma on Morton Island just off Brisbane.
In 10 years of operation, it processed more than 6,000 humpback whales.
By 1962, the humpbacks migrating up Australia’s east coast had been reduced from an estimated 15,000 or more to perhaps a few hundred.
That year, the station caught only 68 whales, and it shut its doors.
Australia’s very last whaling station at Chains Beach near Albany in Western Australia closed in 1978.
And then something remarkable happened.
The humpbacks came back.
Surveys from Point Lookout on Minerabar, North Strad Island, tracked the East Coast population growing at around 10 to 11% a year, close to the fastest rate a humpback population can physically grow.
By 2015, there were estimated to be around 24,000.
In 2022, the humpback was removed from Australia’s threatened species list.
Those whales are not immortal.
Every year, some of them die out at sea, and many of those bodies do what whale bodies have always done.
They sink.
Somewhere off the east coast, off the west coast, out past the shelf in the cold and the dark, Australia’s recovered whales are once again becoming whale falls.
Each one a feast for the sleeper sharks and the hagfish.
A home for the bone devourers.
A decades long island of life for animals that most of us will never see and many of which have never been named.
The humpback comeback is usually told as a story about the surface, about whale watching boats and breaching calves and crowds on the headlands every winter.
But it is also a story about the bottom of the sea.
We spent a century emptying the deep of its whales.
We are only now beginning to understand what we may have taken away down there.
And it took a cow cut in half sitting under a lonely camera off the coast of Hainan to show us how quickly the deep comes alive when food arrives from above.
Eight sharks, all of them, it seems, female, taking turns in the dark more than 1 and a half kilometers down in a sea where no one had ever recorded them.
They had not been hiding.
They had been waiting.
The wild is not gone.
