In the food-deficient environment at the ocean floor, whale carcasses become veritable feasts. Scavengers like sleeper sharks bite and tear the soft tissue. Crustaceans colonise the exposed bones and the enriched sediments alongside. Other organisms break down bone lipids, emit hydrogen sulphide in the process, and spawn a chemosynthetic-based community.
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Source: http://nautil.us/blog/the-strange-ecosystem-in-the-sea-dead-whales