Bone-Eating Worms Fed on Giant Marine Reptiles

A bizarre species of bone-eating worms that dates back to prehistoric times had a unique appetite, new research shows, as it fed on the carcasses of ancient giant marine reptiles.

Scientists at Plymouth University found that Osedax - dubbed the "zombie worm" - originated at least 100 million years ago, and survived on a diet of bones from plesiosaurs and sea turtles, among other prehistoric reptiles.

While experts thought that the worm evolved at the same time as whales, it turns out this gruesome species dates back much further, providing insight into the genesis of the species and its implications for fossil records.

"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." Researcher Dr. Nicholas Higgs said in a statement. "The unusual adaptations and striking beauty of Osedax worms encapsulate the alien nature of deep-sea life in public imagination."

What's more, the "discovery shows that these bone-eating worms did not co-evolve with whales, but that they also devoured the skeletons of large marine reptiles that dominated oceans in the age of the dinosaurs," Higgs added. "Osedax, therefore, prevented many skeletons from becoming fossilized, which might hamper our knowledge of these extinct leviathans."

Tiny Osedax - measuring at only finger-length - can be found in oceans across the globe living at depths of up to 4,000 meters (~13,000 feet). And since it belongs to the Siboglinidae family of worms, it characteristically lacks a mouth and digestive system.

So how does this worm feast on the bones of dead giant marine reptiles? It penetrates bone using root-like tendrils through which it absorbs bone collagen and lipids, which are then converted into energy by bacteria inside the worm.

Since Osedax favors eating whale bones, scientists had long believed that they co-evolved 45 million years ago. However, after studying fossil fragments taken from an ancient plesiosaur and sea turtle fossil unearthed in the United Kingdom, they found tell-tale bore holes and cavities consistent with the burrowing technique of Osedax.

"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 Dr. Silvia Danise, who was involved in the study.

"By destroying vertebrate skeletons before they could be buried," she added, "Osedax may be responsible for the loss of data on marine vertebrate anatomy and carcass-fall communities on a global scale. The true extent of this 'Osedax effect', previously hypothesized only for the Cenozoic, now needs to be assessed for Cretaceous marine vertebrates."

The results were published in the journal Biology Letters.

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