Scientists have discovered a new genus of worms that can munch down rocks and excrete them into the sand. The discovery leads researchers to believe that these worms can beneficially help shape rivers and, possibly, be a new source in the production of new antibiotics.
Initially, researchers believed that the new shipworm—Lithoredo abatanica—is a type of teredinid and is a part of the shipworm family. Shipworms have long been a menace to humankind; popular in the mid-1700s when the worms would reduce down wood in ships, piers, and dikes that led to a slew of problems in a time when most of the human development depended on the sea.
Favorably, with better observation and research, scientists have discovered that the previously thought wood-eating worms preferred a much different diet: rocks.
Like the shipworm, Lithoredo abatanica is considered to be a bivalve (like clams or mussels). In the case of these worm-like clams, however, their shells are rather small and do little to protect the animals from predators.
“Although many other invertebrate species are known to burrow in stone, we are not aware of other species that burrow in stone by ingesting the substrate,” researchers write. “We suggest that this unusual habit is a consequence of this species having evolved from a wood-feeding ancestor since the mechanism by which shipworms burrow in wood involves both ingestion and digestion of the excavated wood.”
The tiny, worm-like creature—thick, white, and can grow to be more than a meter long—was first spotted back in 2006 during an expedition by the French National Museum of Natural History in thumb-size burrows in the limestone banks of the Abatan River in the Philippines. But it wasn’t until 2018 that scientists were able to study the organism in detail.
“This one is so unusual we had to create a new genus,” says Dan Distel, director of the Ocean Genome Legacy Center at Northeastern University in the US. “This species is found only in a stretch of this river in the Philippines that runs about three to five kilometers.”
Furthermore, the rock-eating shipworm is different from its wood-eating counterpart because of its anatomy. Shipworms are like clams where they have two shrunken shells that have been modified into drill heads. While there are hundreds of sharp invisible teeth that cover the shells in the wood eater, the rock-eating shipworm has just dozens of thicker, millimeter-size teeth that scrape away rock, researchers told in a report in the Proceedings of the Royal Society B.
Researchers were also able to observe that the bivalves can eat their way through limestone but speculate that the rocks do not serve as a direct source of nutrition for the worms. Rather, the rocks serve as a place of refuge and a defense mechanism to avoid predators. Furthermore, these worms get the majority of their nutrition from bacteria that live in their gills, as well as from planktonic algae and bits of plants sucked in by a siphon at the clam’s back end for nourishment but it’s also possible that the bits of rock aid in their digestion.
Though mostly thought of as pests, shipworms play an important role as ecosystem engineers. Shipworms are able to create tunnels that serve as habitat for a diverse set of marine life. In a study published in the US National Library of Medicine National Institutes of Health, researchers concluded that “if it was not for the tunnels created by teredinids, [large woody debris or] LWD would have significantly fewer animals, and a reduced nursery function, important for species such as octopods, and dartfish (Hendy et al., 2013).” Furthermore, the study also indicated that the shipworms also paved the way for a more diverse marine life along mangrove ecosystems.
Scientists suggest the new worm-like rock-eating species “may also play a role in shaping its ecosystem and creating new habitats.” Particularly, by providing shelters to other organisms as these creatures burrow their way into limestone.
“The bacteria in their gills could also provide us with a new source of pharmaceuticals, potentially whole new classes of antibiotics to help combat the rising menace of drug-resistant bacteria,” Science Alert reported.