The Whale Fall: A Dead Whale Feeds a City
The deep sea floor is mostly a desert: cold, dark, and poor in food. A whale carcass arriving on it is an event. A single large whale can deliver tens of tonnes of organic matter to the abyss at once, and ecologists have learned to read its decomposition as a sequence of distinct communities.
The mobile scavenger stage
Within hours, sharks, hagfish and crustaceans strip the soft tissue. This stage is fast — months to a couple of years for a large carcass — and highly mobile: these animals are adapted to find rare, scattered windfalls.
The enrichment stage
Once the flesh is gone, the sediment around the skeleton is saturated with organic matter. Polychaete worms, snails and crustaceans colonise the bones and the enriched mud, reaching densities far above the surrounding sea floor. This can last years.
The sulphophilic stage
The longest phase belongs to bacteria. Whale bones are rich in lipids, and bacteria break them down anaerobically, producing hydrogen sulphide. That supports chemosynthetic organisms — mussels, clams and tube worms — that make their own food from chemical energy, exactly as communities around hydrothermal vents do. Some of these species are known from both habitats, which is one clue that whale falls may act as stepping stones between vents.
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What powers the last stage of a whale fall?
Which stage comes first?
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