Bones left on land can survive for a very long time. The fossil bones of dinosaurs on display in museums around the world are testaments to their durability. Underwater, however, the situation can be very different. Weird and oddly wonderful so-called zombie worms can slowly devour huge whales skeletons. These 1 to 3-inch Osedax worms were first discovered in 2002, living in the bones of a rotting gray whale on the deep seafloor, nearly 10,000 feet deep in Monterey Bay. Since then 32 different species of these worms have been identified.
Remarkably, the worms lack both mouths and digestive organs. They eat away the whalebone by producing acid from their skin that dissolves bone, releasing the fat and protein trapped inside. As the bone is eaten away the worm establishes a “root system” that burrows into the bone. The fats are consumed by symbiotic bacteria. Exactly how the zombie worm itself is fed is not entirely clear. Nevertheless, the worms can devour a sunken whale skeleton in as little as a decade.
Only female zombie worms are directly involved in the bone-eating. The male worms are microscopic and live within the gelatinous tubes surrounding a female’s trunk. The female worms accumulate more males as they grow.
The zombie worms also eat large fish bones and have been known to devour cow bones thrown overboard.