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A whale fall occurs when the carcass of a whale has fallen onto the ocean floor, typically at a depth greater than 1,000 m (3,300 ft), putting them in the bathyal or abyssal zones.

Whale falls were first observed in the late 1970s with the development of deep-sea robotic exploration. Since then, several natural and experimental whale falls have been monitored through the use of observations from submersibles and remotely operated underwater vehicles (ROVs) in order to understand patterns of ecological succession on the deep seafloor. Deep sea whale falls are thought to be hotspots of adaptive radiation for specialized fauna. Organisms that have been observed at deep-sea whale fall sites include chordates, arthropods, cnidarians, echinoderms, mollusks, nematodes, and annelids. New species have been discovered, including some potentially specializing in whale falls. It has been postulated that whale falls generate biodiversity by providing evolutionary stepping stones for multiple lineages to move and adapt to new, environmentally challenging habitats. Researchers estimate that 690,000 carcasses/skeletons of the nine largest whale species are in one of the four stages of succession at any one time. Whale falls are able to occur in the deep open ocean due to cold temperatures and high hydrostatic pressures. In the coastal ocean, a higher incidence of predators as well as warmer waters hasten the decomposition of whale carcasses. When the lungs deflate, the whale carcasses can reach the seafloor quickly and relatively intact due to a lack of significant whale fall scavengers in the water column.

This helps to sustain the community structure that develops around a whale fall, but it also has potential implications for the biological pump, or the flux of organic material from the surface ocean to depth.

The earliest indication that whale carcasses could host specialized animal communities occurred in 1854 when a new mussel species was extracted from a piece of floating whale blubber. The first recorded abyssal whale fall was discovered by US Navy bathyscaphe pilots LT Ken Hanson, Master Chief George Ellis and LT Tom Vetter diving in bathyscaphe Trieste II (DSV-1) on 19 February 1977. The whale was considered to be a gray whale based on the size of the bones and the skeleton, the lack of teeth and its location west of Santa Catalina. The first whale fall ecosystem, which included a chemoautotrophic assemblage living on the anaerobic breakdown of organic material in whale bones, was discovered by a team of scientists led by University of Hawaiʻi oceanographer Craig Smith in 1987. Many other whale falls have since been found by more researchers and deep-sea explorers, as well as by naval submarines. A June 2026 article in Nature describes the discovery of a "whale necropolis" that includes both modern whale falls and fossil whale remains in the Diamantina fracture zone.

Though marine leeches have been observed at whale falls, polychaetas tend to be the focus of much of the annelid research on whale falls. Members of Osedax can be found on whale falls across the globe, though different species have been discovered on Atlantic whale falls than on Pacific whale falls.

There are four stages of decomposition associated with a whale fall.

The addition of sulfur reduction in both sediments and high lipid whale bones is a key factor for why whale falls are able to sustain deep-sea communities for extended periods of time.

The effects of this on benthic whale fall community assemblages is not well understood. Whales stored massive amounts of carbon that were exported to the deep sea during whale fall events.

In particular, the chance discovery of a whale shark carcass and three mobulid ray carcasses led to observations on the communities that form surrounding large elasmobranch falls as opposed to whale falls. Researchers have compared sauropod carcasses to modern whale fall events.

Quick Facts

• Members of Osedax can be found on whale falls across the globe, though different species have been discovered on Atlantic whale falls than on Pacific whale falls.
• When the lungs deflate, the whale carcasses can reach the seafloor quickly and relatively intact due to a lack of significant whale fall scavengers in the water column.
• Organisms that have been observed at deep-sea whale fall sites include chordates, arthropods, cnidarians, echinoderms, mollusks, nematodes, and annelids.
• New species have been discovered, including some potentially specializing in whale falls.
• Researchers estimate that 690,000 carcasses/skeletons of the nine largest whale species are in one of the four stages of succession at any one time.

Source material: Wikipedia - "Whale fall". Adapted and summarized for DiscoverScroll. Original contributors are credited through the linked Wikipedia article. Read original on Wikipedia. CC BY-SA 4.0. Changes were made from the original.