A vast “necropolis” of whales—packed with both fresh remains and fossils millions of years old—has been found on the floor of the Indian Ocean, where Chinese scientists say the carcasses nourish sprawling deep-sea communities in an otherwise inhospitable realm.
The site is the deepest and oldest whale graveyard yet documented, according to research published in the journal Nature, with some fossils dated to 5.3 million years ago.
Peering out from a small submersible, the research team reported seeing an array of unusual creatures—many thought to be new to science—clustered around the bones and feeding on what the whales left behind.
Among nearly 500 skeletons mapped as deep as 7,000 metres, the scientists also identified a new, now-extinct whale species. The remains stretch along a 1,200km corridor of bones in the Indian Ocean west of Australia.
Lead study author Xiaotong Peng of the Chinese Academy of Sciences said the magnitude of the find caught the team off guard.
Scientists have long understood that when whales die and sink, their bodies—known as “whale falls”—become concentrated food sources for organisms living on the seafloor.
“But discovering a necropolis of this scale was completely unexpected. The size of distribution, the depth and the age range were far beyond anything we had imagined,” the scientist said.
The researchers offered several possible explanations for why so many whales ended up in the same corridor, including the idea that it is a favoured foraging ground and that a V-shaped trench may act like a chute, directing carcasses down to the ocean floor.
‘Vibrant ecosystems’
The discovery was made during 32 dives in 2023 by the Fendouzhe submersible, though the findings were only revealed yesterday.
The craft carried up to three people on each descent and used robotic arms to retrieve fossil samples.
Study co-author Peng Zhou said seeing the graveyard firsthand “was a truly incredible experience”.
“The vibrant ecosystems we saw offered a completely different perspective on this otherwise dark and cold ocean floor,” the researcher said.
The team found a range of animals living off the carcasses, including jellyfish, worms, snails, crustaceans, brittle stars and molluscs known as bivalves.
Using the concentration of bones—most from beaked whales—as a basis for extrapolation, the scientists estimated the broader area, called the Diamantina Zone, could contain more than 10 million carcasses.
The soft tissue and lipids contained within that volume of remains “translates to roughly 6.7 million tonnes of sequestered carbon,” Xiaotong Peng said.
That stockpile represents a massive, long-lasting buffet for seafloor life, akin to how hydrothermal vents support rich ecosystems in the deep.
The researchers also noted that some species observed at the whale falls are known from hydrothermal vents and cold seeps, raising the possibility that carcasses help link far-flung deep-sea communities.
Although this is the largest whale graveyard identified so far, the study said fossils recovered during trawling indicate others may exist off South Africa, the Iberian peninsula and the Crozet islands.
‘Truly unique discovery’
University of Hawaii oceanographer Craig Smith, who discovered the first whale fall in 1987 but was not involved in the new research, told AFP it was “extremely exciting”.
“The vast number of fossil whale falls documented, including a new species of beaked whale, is truly amazing and is of major importance to understanding whale evolution and whale distributions over geologic time,” he said.
Whale fall researcher Amy Baco-Taylor at Florida State University told AFP the “remarkable discovery” would “likely provide many new insights”.
“It does seem very strange” that so many whales died in this area, Ms Baco-Taylor admitted, adding that “we don’t know enough about whale consciousness”.
US palaeontologist Stephen Godfrey compared the “truly unique discovery” to past major underwater finds, such as when scientists first identified hydrothermal vents teeming with life on the ocean floor in 1977.
He called for future submersible voyages to find more whale graveyards across the world.
This discovery “reminded me of a trailer for the first in a series of epic movies”, Mr Godfrey commented in a linked Nature paper.
“I hope that there will be many more of these blockbusters to come,” he added.
