Researchers discover whale graveyard at record 7002-metre depth in Indian Ocean

A Chinese-led team discovered the world’s deepest known whale graveyard at 7002 metres in the Dordrecht Deep section of the Diamantina Zone during 32 dives along 1200 kilometres of seafloor in early 2023. The site lies more than 1100 kilometres south-west of Perth, Western Australia. 26 million years old.

The expedition formed part of the Global Hadal Exploration Programme. The crewed submersible Fendouzhe used manipulator arms to collect 43 fossil specimens and documented 485 active whale-fall and fossil-whale sites. One 5-metre Antarctic minke whale carcass was observed on the seafloor.

Invertebrates such as bone-eating worms and brittle stars reached densities of up to 2800 individuals per square metre at the sites. Most younger fossils belonged to Andrews’ beaked whale and the strap-toothed whale. The team formally described one new species, Pterocetus diamantinae, and recovered possible baleen-whale ribs at 5656 metres.

55 millimetres per thousand years over the past 5 million years. Many bones are coated with ferromanganese oxides that slow degradation. Peng Zhou of the Chinese Academy of Sciences said the powerful lighting system allowed visibility of tens of metres on the otherwise pitch-dark seafloor.

Xiaotong Peng of the Chinese Academy of Sciences said the combination of dense bone, slow burial, and mineral coatings preserved the remains. “So it’s really a combination of bone density, slow burial, and mineral coatings that has allowed these bones to escape being eaten for over 5 million years,” he said.

Giovanni Bianucci of the University of Pisa said several fragmentary specimens may represent additional unknown species.