5.3-Million-Year-Old 'Whale Necropolis' Discovered 7,000 Meters Deep in Indian Ocean

A "whale necropolis" has been discovered in the deep sea of the Indian Ocean, featuring hundreds of whale fossils dating back up to 5.3 million years and active whale fall sites where ecosystems are still maintained, widely distributed across the seabed at depths of 4,200 to 7,000 meters.

A joint research team from Italy and New Zealand, led by Dr. Xiaotong Peng of the Chinese Academy of Sciences, announced on Thursday (June 11) in the scientific journal Nature that they have discovered a massive whale graveyard at depths of 4,616 to 7,000 meters in the Diamantina Zone of the southeastern Indian Ocean.

The research team stated that this area, where whale fossils and carcasses stretch for more than 1,200 kilometers along the deep-sea floor, is highly likely to be the deepest and most extensive whale necropolis known to date, and is expected to open a new window into the study of deep-sea ecosystems and whale evolution.

Numerous organisms adapted to extreme environments live in the deep sea, and one of the fascinating phenomena is the "whale fall" ecosystem, which is formed when the carcass of a dead whale sinks to the ocean floor.

Whale falls are a relatively common phenomenon, with about 70 sites reported across various oceans and depths so far.

The research team pointed out that while whale fall sites gather a highly diverse range of organisms to form unique deep-sea ecosystems, their distribution is regionally uneven, and discoveries and documentations have only been made intermittently, leaving their actual distribution and ecology insufficiently understood.

Indeed, whale fall sites are known to act as "biodiversity oases" in the deep sea, gathering various organisms that use whale bones and residual organic matter as energy sources. Most reported whale falls have been found at depths ranging from tens of meters to about 4,000 meters.


The research team first discovered a whale fossil at a depth of 7,002 meters in 2023 while exploring the Diamantina Zone in the southeastern Indian Ocean using the deep-sea submersible Fendouzhe. Since then, through 32 diving expeditions, they have identified 485 sites with whale fossils and traces of whale falls at depths between 4,616 and 7,001 meters.

The whale fossils and carcasses were found to be distributed over approximately 1,200 kilometers along the seafloor, with five whale fall sites currently supporting diverse biological communities.

The deepest whale fall was a beaked whale carcass found at a depth of 6,789 meters, and the skeleton of a 5-meter-long Antarctic minke whale (Balaenoptera bonaerensis) was also identified.

Unique biological communities, including brittle stars, bone-eating Osedax worms, and bivalves symbiotic with chemosynthetic bacteria, had formed around the whale carcasses.

The research team stated that the large invertebrates surveyed in the whale fall ecosystems belong to 35 taxa, and many of them are likely to be new species not yet reported to the scientific community.

Fossil analysis revealed that most of the remains belonged to beaked whales specialized in deep-sea diving, with numerous fossils of extant species such as Andrews's beaked whale (Mesoplodon bowdoini) and the strap-toothed whale (Mesoplodon layardii) being discovered.

Along with previously known extinct species, a new extinct species of beaked whale, Pterocetus diamantinae, was also identified.

In addition, isotopic dating of 33 whale fossils revealed that the oldest fossil dates back approximately 5.26 million years.

This suggests that whale falls have continuously occurred in this region since at least the Early Pliocene, about 5.3 million years ago.

The research team said this discovery extends the depth range of whale fall ecosystems by more than 2,500 meters, supporting the hypothesis that whale falls serve as stepping-stone habitats that aid the evolution and dispersal of deep-sea chemosynthetic biological communities.

They added that the study reshapes the understanding of the distribution range and biogeography of whale fall ecosystems, demonstrating that parts of the deep-sea floor act as fossil archives that allow the tracking of cetacean evolution over geological timescales.

(Photo: Global TREnD, courtesy of IDSSE, Yonhap News)
※ Please note: This article was translated by AI and may contain errors.