Researchers Find World’s Deepest Known Whale Graveyard at 7 Kilometres

A Chinese-led team has identified the world’s deepest known whale graveyard at 7002 metres in the Dordrecht Deep of the southern Indian Ocean. Peng Zhou at the Chinese Academy of Sciences and colleagues conducted 32 dives in the crewed submersible Fendouzhe along 1200 kilometres of the Diamantina Zone seafloor in early 2023. The expedition formed part of the Global Hadal Exploration Programme.

The first bones were spotted at 7002 metres, more than 1100 kilometres south-west of Perth, Western Australia. Researchers later recorded densities reaching 760 individual whales per square kilometre across both ancient and recent carcasses. 26 million years old.

Among the younger remains, most belonged to Andrews’ beaked whale and the strap-toothed whale. One new species, Pterocetus diamantinae, has been formally described. Fossils at 5656 metres included possible baleen-whale ribs.

A recently fallen 5-metre Antarctic minke whale was also documented at the site. Invertebrates such as bone-eating worms and brittle stars were observed at densities up to 2800 individuals per square metre, many thought to be new species. The team recorded 485 active whale-fall and fossil-whale sites in total.

Zhou said the submersible’s lighting allowed visibility of tens of metres across the otherwise pitch-dark seafloor. He described the scene as “a little scary, but also incredibly fascinating” and added that the site represented “the final resting place of millions of whales – some over 5 million years old”.

55 millimetres of sediment per thousand years and coatings of ferromanganese oxides, has preserved them for millions of years.

Giovanni Bianucci at the University of Pisa said several fragmentary specimens may represent additional undescribed species. Most fossils recovered were beaked-whale rostra. Culum Brown at Macquarie University, who was not involved in the study, called the find an “amazing discovery” and said the density of remains was “incredible”.