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A whale’s second life cycle has three distinct and active ecological stages on the sea floor:
- The mobile scavenger stage
- The enrichment-opportunist stage
- The sulfophilic stage
For the next two years, in the enrichment-opportunist stage, crustaceans, marine worms and other smaller organisms feed on the leftovers of the larger scavengers. These animals densely populate the nutrient-rich soil surrounding the newly exposed whale bones, feeding on blubber left behind by the sharks and hagfish.
The key to this stage is the feast of fats and oils, known as lipids, in the whale’s skeletal system. Lipids can account for up to 60 percent of the weight of whale bones, according to scientists. It’s called the sulfophilic stage because specialized bacteria break down the whale’s oils, producing vast amounts of sulfide and, through chemical processes, make organic matter that a diverse community of mussels, worms, snails and other small animals can survive on for decades.
There is also a fourth, inactive stage of a whale fall, known as the reef stage. During this stage, the skeletal remains of the whale are colonized by suspension feeders like tube worms, exploiting the unique way currents flow around the skeletal structure.
Originally discovered in 1987 by University of Hawaii researcher Craig Smith, deep ocean whale falls play host to an entire ecosystem of unique organisms.
Researchers have discovered as many as 190 species cohabiting whale falls at one time. “They appear to have the highest local species richness of any known deep-sea, hard-substrate community,” said Smith in his paper Bigger is Better: The Role of Whales as Detritus in Marine Ecosystems.
Smith and his colleagues set up whale-fall experiments in the Pacific, sinking large dead whales to the deep ocean and doing time-lapse research to study the unique habitats. Many of the diverse life forms that researchers find on whale falls have been found nowhere else in the world!
To learn more about whale falls check out this feature in the Feb. 2010 edition of Scientific American.