A Different Kind of Shipworm: It Eats Rocks and Excretes Sand

• In June 2019, Researchers from Northeastern’s Ocean Genome Legacy Center found an unusual kind of shipworm thriving in the Abatan River in the Philippines.
• Unlike other shipworms that bore and fed on wood, these bivalves eat rock and excrete sand.
• These shipworms were first spotted in 2006, but it was not until 2018 that researchers were able to study them in detail.
• Researchers suggested that these are a new genus and species of shipworm.

The local residents of Bohol have been talking about a rock-eating shipworm. Known as ‘Antingaw’ to the locals, they believed ingesting it helps to induce lactation in young mothers.

Eventually, the locals led a team of scientists to the ‘mudstone cliff’ along the Abatan River where the bivalves live. Holding a chisel and a hammer, Reuben Shipway, a post-doctoral researcher at the University of Amherst, cracked a rock open.

Shipway later discovered how the mollusks ate its way through the limestone bedrock.

Unlike other water-dwelling bivalve mollusks that feed on wood, the Lithoredo abatanica—as the scientists named it—bore in carbobate limestone by eating rocks and excreting it as sand.

The Lithoredo abatanica (litho=rocks; teredo=shipworm) are long, thick, and white. They look more like worms than mollusks.

They also have larger, flatter teeth unlike the wood-eating shipworms, Phys.org reported.

Dan Distel, director of the Ocean Genome Legacy Center at Northeastern University in the US said, “This one is so unusual, we had to create a new genus.”

Reuben Shipway said, “Most other shipworms are as skinny as your finger….”

“These animals are quite chubby, robust. They look really different. Where they get their nutrition we don’t know,” he told IFLScience.

According to researchers, this new species of shipworm was actually spotted in 2006, but was studied in detail only recently.

In a journal published in the Proceedings of the Royal Society B, Shipway and his co-author wrote: “These animals are among the most important in the river and in this ecosystem.”

He added, “As they bore elaborate tunnels in the limestone bedrock, these animals change the course of the river and provide a really rich environment for other aquatic species to live in.

“So far, this is the only place on earth that we know these animals exist.”

The team had many theories why this type of shipworm eats rocks. However, they were not able to determine its real motive. It is possible, however, that they utilize a symbiont-dependent mode of digestion like other shipworms.

“Lots of other species of shipworms rely on their gill symbionts to provide the nutrition. Our next research priority is to check whether these symbionts are present in these gills and try to figure out if they are helping to provide nutrition for these animals, ” said Shipway.

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