The root-like tissues worms of the Osedax family use to attach to bones contain acid-secreting enzymes, researchers from the Scripps Institution of Oceanography at the University of California, San Diego, reported.
Living on the skeletons of whales and fish -- "Osedax" is Latin for "bone devourer" -- the worms have intrigued marine scientists since their discovery in 2002.
Scientists wanted to understand how worms fed on bone since they lack body parts that could physically "drill" into bones.
Scripps researcher Sigrid Katz and colleagues said they suspected the worms had a chemical strategy for penetrating the bones. The found acid-secreting enzymes were abundant in the root-like parts of the worms that attach them to bones.
"The acid is secreted through the skin of the roots region," Katz told the BBC.
"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 said.
Seventeen species of the "zombie" worms have been recorded worldwide, including in the North Atlantic Ocean off the coast of Sweden, and the Pacific Ocean off the coasts of Japan and California.