Bone-Eating 'Zombie' Worms Devoured Prehistoric Marine Reptiles

A strange, gruesome species of bone-eating worm that was thought to have evolved at the same time as whales has now been dated back to prehistoric times. It turns out that these worms feasted on the carcasses of giant marine reptiles.

Popularly called the "zombie worm" in media, Osedax originated at least 100 million years ago. It consumed the bones of prehistoric reptiles such as plesiosaurs and sea turtles.

"The exploration of the deep sea in the past decades has led to the discovery of hundreds of new species with unique adaptations to survive in extreme environments, giving rise to important questions on their origin and evolution through geological time," said Nicholas Higgs, one of the researchers, in a news release. "The unusual adaptation and striking beauty of Osedax worms encapsulate the alien nature of deep-sea life in public imagination."

The bone-eating worm is about the length of a finger, and can be found in oceans across the globe at depths of up to 4,000 meters. These worms penetrate bone using root-like tendrils through which they absorb bone collagen and lipids that are then converted into energy by the bacteria inside the worm. Typically, they feast on whales bones.

This latest study, though, reveals that whale bones weren't their only food of choice. Scientists studied fossil fragments taken from a plesiosaur and found tell-tale bore holes within the bones.

"The increasing evidence for Osedax throughout the oceans past and present, combined with their propensity to rapidly consume a wide range of vertebrate skeletons, suggests that Osedax may have had a significant negative effect on the preservation of marine vertebrate skeletons in the fossil record," said Silvia Danise, one of the researchers. "By destroying vertebrate skeletons before they could be buried, Osedax may be responsible for the loss of data on marine vertebrate anatomy and carcass-fall communities on a global scale. The true effect of this 'Osedax effect,' previously hypothesized only for the Cenozoic, now needs to be assessed for Cretaceous marine vertebrates."

The findings are published in the journal Biology Letters.

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