External view of an Osedax specimen
Discovery of the new molecular tract, which secretes calpain14 enzyme, could lead to research on a cure for food allergies. [Picture Representation]Greg Rouse, Martin Tresguerres

"Bone worms" or "zombie worms", belonging to the genus Osedax, use bone-melting acid to drill into thick whale bones lying on the seafloor and feed on them, reports a new study.

These worms were first discovered in 2002 by researcher Greg Rouse and his colleagues from the Scripps Institution of Oceanography at University of California-San Diego (UCSD), in an underwater valley called the Monterey Submarine Canyon, which is located off the California coast.

The small creatures use the whale bones as shelter to mate and feed on the nutrients inside. The faceless, gutless (lack of digestive system) worms excrete acid, which is produced in large quantities by protein-containing proton pumps in their skin.

"The acid presumably allows the worms to release and absorb collagen and lipids that are trapped in bone," Martin Tresguerres, a marine physiologist at the Scripps Institution of Oceanography in La Jolla, Calif., said in a statement. "This model is remarkably similar to how mammals repair and remodel bone, however Osedax secrete acid to dissolve foreign bone and access nutrients."

As "bone worms" lack mouths, they take help from bacteria to process the nutrients. Bacteria living in a symbiotic relationship within the worms help in breaking down food for digestion. However, the exact mechanism of how the process works is not clear.

There is some evidence which suggests that the symbiotic bacteria metabolise bone-derived collagen into other diverse organic compounds, and subsequently the worms digest the bacteria for their nutrition.

"The Osedax symbiosis shows that nutrition is even more diverse than we imagined and our results are one step closer in untangling the special relationship between the worm and its bacteria," said Sigrid Katz, a postdoctoral researcher at the Scripps Institution of Oceanography.

Researchers are further planning to study (by collecting additional bone samples with live worm specimens) how the "bone worms" transport and utilise the nutrients they have unearthed. They would also be studying the worms' physiology by maintaining live Osedax in aquaria at Scripps.

The details of the findings are published in the Proceedings of the Royal Society B journal.

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