The largest whale graveyard ever discovered, nicknamed the “whale necropolis” because of its immense size

An Abyssal Necropolis Discovered in the Diamantina Area

Deep below the surface of the southeastern Indian Ocean, the seafloor harbors an unexpected secret. Scientists have located a veritable “whale graveyard,” which stands as the largest and deepest collection of cetacean remains ever identified on the planet, according to a recent scientific study. This extraordinary site spans a vast and rugged portion of the ocean floor known as the Diamantina Zone.

This discovery is the result of work by a team from the Institute of Deep-Sea Science and Engineering (IDSSE) at the Chinese Academy of Sciences. These researchers collaborated closely with scientists from the University of Pisa in Italy, as well as with experts from Earth Sciences New Zealand, based in Wellington.

Their initial focus was on a fracture zone stretching approximately 750 miles (1,200 kilometers) along the seafloor. Until this unprecedented exploration, the scientific community had never established a link between this specific region and the presence of whale carcasses. The researchers logically named this area a “whale necropolis,” a graveyard formed by bones that have accumulated there over millions of years.

A Record-Breaking Expedition into the Depths

In early 2023, the scientific team boarded the research vessel Tansuoyihao and deployed a manned submersible named Fendouzhe. Over the course of 32 meticulous dives, the crew inspected a long underwater corridor located at depths ranging from 15,000 to 23,000 feet (4,616 to 7,001 meters). This technical mission made it possible to map an environment that had previously been largely unknown.

The on-site inventory revealed a colossal scale. Instruments and direct observations identified five active whale graveyards and no fewer than 476 fossilized cetacean sites, all scattered throughout this oceanic rift zone.

Prior to this mission, virtually all documented whale carcasses were found at depths of less than 13,000 feet (4,000 meters). The previous record for an active site was 4,204 meters in the southwestern Atlantic Ocean. This new site drastically pushes that limit: an active community, consisting of three beaked whale vertebrae, was located at 22,200 feet (6,789 meters), making it the deepest ecosystem of its kind ever described.

A thriving ecosystem built on bones

A whale carcass in the abyss is much more than just a pile of bones. Each skeleton transforms into a thriving island of life in the midst of an oceanic desert that is otherwise poor in food. On these remains, researchers have observed thick white microbial mats as well as a multitude of highly specialized animals that dominate the scene.

The biological landscape is populated by brittle stars, bone-eating worms of the genus Osedax, and bivalves that feed through chemosymbiosis. The largest carcass, measuring 16 feet (5 meters) and located at a depth of 18,400 feet (5,610 meters), belonged to a minke whale from the Antarctic. Scientists identified it based on a characteristic ear bone and a nearly complete mitochondrial genome.

This extreme environment is home to numerous potential species that have likely never been scientifically named. The team collected genetic data from 21 species, but only one bivalve could be formally linked to a known name. Three species of brittle stars appeared exclusively on whale bones and nowhere in the surrounding mud, suggesting a strict adaptation to this organic-rich habitat. Additionally, a wood-eating sea daisy of the genus Xyloplax was spotted on a carcass for the very first time, setting the depth record for this genus.

The complex dynamics of this spectacular accumulation

The bones tell the precise story of how these whales ended their journey in these abyssal depths. The majority of the remains belong to two species of beaked whales capable of very deep dives: Layard’s beaked whale and Andrews’ beaked whale, both known to inhabit these waters. These predators hunt squid and fish along steep slopes and in deep trenches, making the Diamantina area an ideal hunting ground despite the dangers.

Venturing to such depths carries deadly risks. By pushing the limits of their physiology, some whales perish during their dives and eventually sink to the seafloor of the area. The local topography contributes to this accumulation: the area has a V-shaped geological profile that channels the sinking carcasses directly toward the bottom of the trench.

Antarctic minke whales and northern right whales, which feed near the surface, contribute differently to this marine graveyard. Their presence is explained by carcasses drifting toward the bottom from a shared migration route. From a conservation perspective, the ocean floor in this area accumulates very little sediment, leaving the bones exposed for an exceptionally long time. The beaks of beaked whales, which are particularly dense, are especially durable, protected by a slowly forming coating of iron and manganese oxides.

Five million years of invaluable biological archives

To determine the age of the remains, the team measured strontium isotopes in 33 fossilized bones. The results indicated ages ranging from recent times to 5.26 million years ago. The oldest dating dates back to the Lower Pliocene, proving that whales have been dying and being deposited in this area since well before the emergence of our own species. The fossils include species of beaked whales that are still alive today, as well as several extinct species, including a newly identified one named Pterocetus diamantinae.

Statistical data suggest a hidden abundance of staggering magnitude. Whale remains reach a density of 759.5 individuals per square kilometer, and extrapolations indicate that the area could contain more than 10 million carcasses in total. This represents a vast reservoir of carbon trapped on the seafloor, estimated by researchers at approximately 6.7 million tons—the equivalent of thousands of years of slow organic drift from the upper ocean.

Aligned along a single axis, these whale falls form a veritable pathway through the deep waters. Many animals discovered here are also found near cold seeps and hydrothermal vents, suggesting that these carcasses help chemoautotrophic communities to spread. According to the study published in the journal Nature, beaked whales—previously known mainly from rare strandings—are represented in this Diamantina necropolis by a direct fossil record that traces their evolution since the Pliocene. Such graveyards may still lie hidden in other unexplored regions of the world’s oceans.

Source: earth.com

The largest whale graveyard ever discovered, nicknamed the “whale necropolis” because of its immense size