Abstract
Whale falls are biodiversity oases at seabeds 1 , 2 , 3 , 4 , 5 , 6 , yet their record from the oceans has remained sparse and fragmentary 6 , 7 . Here we report the discovery of a vast whale necropolis in the Diamantina Zone (4,616- to 7,001-m depth), extending about 1,200 km along the sea floor of the southeastern Indian Ocean. This area has a deep and extensive accumulation comprising five modern natural whale-fall communities and 476 fossil cetaceans recorded. We show that carcasses host specialized communities dominated by brittle stars, bone-boring worms and chemosynthesis-based bivalves and that the fossil record in this area comprises both extant and extinct deep-diving beaked whales. Isotopic dating shows that whale falls in this region have occurred since at least 5.3 million years ago. These findings reshape the understanding of the limits and biogeography of whale-fall ecosystems and establish some deep sea floors as a fossil archive for tracing cetacean evolution over geological time.
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The deep sea is home to myriad life forms that have adapted to extreme environmental conditions. One of the most fascinating phenomena of the deep sea are whale-fall communities, whereby a whale carcass that sinks to the ocean floor 1 , 2 , 3 initiates a highly idiosyncratic ecosystem in association with a variety of physiologically diverse organisms, thus providing crucial insights into the interplay of life and death in the ocean’s depths 4 , 5 , 6 , 7 . Although whale falls are abundant, with more than 70 sites documented across diverse ocean basins and depths 6 , their distribution remains patchy and only sporadically documented 7 .
The species composition and diversity of whale-fall communities are strongly influenced by water depth and related environmental factors, such as temperature and hydrodynamic regime 6 , 8 , 9 . In contrast to deep-sea sites, shallow-water shelf whale falls generally yield different sets of taxa, indicating that highly specialized and species-rich whale-fall communities develop primarily in the food-limited setting of the deep ocean 7 , 10 , 11 , 12 , 13 . So far, however, most whale falls are found between some tens of metres to around 4,000 m water depth 6 , 7 , with the deepest example reaching 4,204 m in the southwest Atlantic Ocean 14 . The biogeography, evolutionary novelty and connectivity of deep-sea whale-fall communities remain poorly understood, first and foremost because of the paucity of data from abyssal and hadal depths 7 .
The Diamantina Fracture Zone lies to the south of the Broken Ridge and Perth Abyssal Plain in the Indian Ocean, stretching about 1,200 km parallel to the Southeast Indian Ridge (Fig. 1 ). It formed as the Australian and Antarctic continents separated between 60 million and 50 million years ago 15 . The rough sea floor topology is the result of block faulting 16 . The deepest regions of the Diamantina Zone cluster in its northwestern section, most notably at the Dordrecht Deep, which reaches a maximum depth of 7,079 m as measured by the conductivity–temperature–depth sensor aboard the human-occupied vehicle (HOV) Fendouzhe in 2023. The Diamantina Zone has not been previously documented to be associated with any whale falls.
Fig. 1: Distribution and abundance of whale fossils and whale falls in the Diamantina Zone. The alternative text for this image may have been generated using AI.
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Orange circles indicate dive locations where whale fossils or whale falls were observed; circle size corresponds to the number of whale remains recorded per dive. Whale falls in the sulfophilic stage are marked with white arrows. White circles denote dives with no observed whale fossil or whale fall. Notably, the distribution of both whale falls and whale fossils is restricted to the Diamantina Zone sea floor; none were detected outside this region. Figure adapted from ref. 51 , Wiley, under a Creative Commons licence CC BY 4.0 .
Whale-fall biota
From 8 February to 17 March 2023, using the Fendouzhe submersible capable of reaching depths of up to 11,000 m on board the R/V Tansuoyihao , we discovered extensive whale falls and fossils in the Diamantina Zone (Fig. 1 and Supplementary Video 1 ). During dive FDZ159, we first encountered whale fossils at a depth of 7,002 m, near the deepest point of the Dordrecht Deep. These fossils were found partially buried in soft surface sediments and lightly coated with black Fe–Mn oxides. Following the initial discovery, we conducted 32 dives to the sea floor, aiming at mapping the spatial distribution and extent of the whale falls and fossils, as well as identifying any associated whale-fall ecosystems. By doing this, we documented and collected samples from 485 whale-fossil sites and active whale falls (Fig. 2 , Extended Data Tables 1 and 2 and Supplementary Table 1 ) from 1,200 km along the sea floor, representing an ecological landmark in the Diamantina Zone.…
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