Deep sea bone worms, which do not have mouths or guts, use acid to dissolve whale skeletons. / courtesy photo

A mouthless and gutless marine worm that feeds off whale bones uses acid secretions to absorb nutrients from the skeletons, according to new research from the Scripps Institution of Oceanography in La Jolla.

The study shines a light on how the deep-sea worms consume nutrients from seemingly indigestible bone matter. It also shows how a small, seemingly insignificant creature could play a key role in the overall ecosystem.

“Because they eat whale carcasses and bones and fish bones, they are probably an important mechanism by which organic matter gets back into the ocean,” said Martin Tresguerres, a co-author of the report. “They dissolve the bone and other animals eat the worms, so all the organic material gets back into the ocean thanks to these worms.”

The other researchers involved in the study, published Tuesday in Proceedings of the Royal Society B, are Sigrid Katz and Greg Rouse.

In 2002, Rouse discovered the worms feeding on a whale carcass and began exploring their unusual existence.

A series of studies revealed that female worms bore into whale bones through extensions known as roots. They use a structure similar to one found in human kidneys to dissolve the hard material of bones and get to the nutrients within them, said Tresguerres, a professor at Scripps.

“We think the worm absorbs the collagen and lipids across the skin,” Tresguerres said. “Inside the worm, there are symbiotic bacteria that metabolize the protein, and then the worm digests the bacteria.”

While the process may sound alien, Tresguerres said it’s similar to the way that cells called osteoblasts remodel bone in human bodies. Eventually, he said, the worms might provide insight into bone formation and degenerative diseases such as osteoporosis.

The worms have been found on carcasses off the coast of California, Japan and Northern Europe, at depths ranging from 2,000 to 13,000 feet, Tresguerres said. Scripps sunk a whale 10 miles off the coast of San Diego last year and will use it to study the bone worms.

“They’re probably everywhere, but because they’re in the deep sea, they’re not easily detected,” Tresguerres said.

Ranging from one to five centimeters in length at maturity, bone worms are related to giant tubeworms that colonize deep-sea thermal vents. Male bone worms never reach maturity; they live in a larval stage within the bodies of females.

During their larval stage, the marine worms appear to form the beginnings of a digestive system. As females mature, that system converts into an organ that houses the bacteria.

The wispy worms may significantly speed up the whales’ composition, Katz said. Researchers previously thought it took decades for a skeleton to break down in the ocean, she said, but the worms consume it in less than a decade.