News release

From: Springer Nature

A vast whale graveyard found on the bed of the Indian Ocean may represent the deepest and most extensive known accumulation of whale fossils, carcasses, and communities supported by the whale falls. The graveyard, reported in Nature this week, stretches 1,200 km along the sea floor at depths of between 4,200 and 7,000 m, with some fossils dating back to around 5.3 million years ago.

Whale falls — when whale carcasses sink to the ocean floor — can create complex localised ecosystems that support a wide range of organisms. However, their record is sparse and uneven, and most known whale falls are found at depths ranging from tens of metres to around 4,000 m, leaving deeper environments poorly understood.

Xiaotong Peng and colleagues report a large whale necropolis extending about 1,200 km along the sea floor in the Diamantina Zone in the southeastern Indian Ocean. They identified 485 whale-fossil sites and 5 active whale falls at depths of between 4,200 and 7,000 m. The density of whale remains reaches up to 759.5 individuals per km². Isotopic dating reveals that the oldest fossils are about 5.3 million years old, indicating that whale falls may have occurred in the region since at least the Early Pliocene. The carcasses host distinct communities dominated by diverse species such as jellyfish, brittle stars, bone-boring worms and chemosynthesis-based bivalves, many of which may be new to science, the authors suggest. Most fossils in this area are from deep-diving beaked whales, both living and extinct, including one extinct whale identified as a new species, Pterocetus diamantinae.

The findings reshape our understanding of deep-sea ecosystems and shed light on the distribution, ecology and evolution of beaked whales.