Deep sea ‘zombie worms’ consume bone by drilling with acid

Earlier this month we reported on the discovery of ‘phlegmy' worms that feed on the bones of dead sea creatures. The biggest question? Exactly how they were able to accomplish this feat, given that they have no mouths or stomachs. But now there's a new clue to this maritime mystery: They're drilling through bone, using acid-secreting enzymes.

The discovery was made by Sigrid Katz from the Scripps Institution of Oceanography, University of California, San Diego, who will present her team's research at the Society for Experimental Biology's annual conference. Katz's findings will be of interest to other marine biologists, who have been baffled by the worms' technique for eating bone.

Deep sea ‘zombie worms’ consume bone by drilling with acid

Investigations into the species had revealed some strange characteristics – including the odd observation that there weren't any males. Writing for BBC, Ella Davies explains that further investigations showed that the males remain in their microscopic larval stage -– living inside the female worms.

And just as strange is the fact that these worms have no mouth, gut, or anus, yet they're somehow able to extract nutrients from bone. It's because of this seemingly inexplicable ability to consume bone without the need for a mouth or stomach that researchers have dubbed it the "zombie worm."

Davies explains the researchers' findings:

By analysing the worms' tissues, the team found that acid-secreting enzymes were abundant in the root-like parts that attach to bones. "The acid is secreted through the skin of the roots region," said Dr Katz.

The acid released from the green-coloured "root" demineralises the bone
"The skin cells in this region are very long cells and the upper end has lots of [microscopic protrusions, which] enlarge the surface multiple times, so lots of acid can be secreted," she explained.

There's still much that needs to be learned about these worms, most of whom can be found in the North Atlantic ocean off the coast of Sweden, and the Pacific Ocean off the coasts of Japan and California.

Top image via BBC/Greg Rouse. Inset image via courtesy Robert C. Vrijenhoek, Shannon B. Johnson & Greg W. Rouse.