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Giant Shipworms Are Nasty Creatures But Can They Really “Eat” Ships?

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April 20, 2017

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What is a giant shipworm and why are we just starting to study these sea creatures?

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Photo of a giant shipworm out of its shell. Image via PNAS.ORG

At the top, two flesh-toned siphons swish water over massive gills. At the bottom, a slimy, eyeless head resembles a mix of wet lips and diseased intestines. In between, a glistening gunpowder blue body stretches up to four feet long. Instead of eating, bacteria in the creature’s gills helps it suck energy from sulfur. The whole thing is sheathed in a curving tusklike tube created from the worm’s excretion of calcium carbonate.

Behold, the giant shipworm, an ancient mariners living nightmare.

The Facts About Giant Shipworms

People have known about giant ship worms for centuries. The three to five-foot long, tusk-like shells that encase the animal were first documented in the 18th century. “The shells are fairly common,” says lead investigator Daniel Distel, Ph.D., a research professor and director of the Ocean Genome Legacy Center at Northeastern University, “But we have never studied the animal living inside.”

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With a live giant shipworm finally in hand, the research team huddled around Distel as he carefully washed the sticky mud caked to the outside of the giant shipworm shell and tapped off the outer cap, revealing the creature living inside.  

“I was awestruck when I first saw the sheer immensity of this bizarre animal,” says Marvin Altamia, researcher at the marine sciences institute, University of the Philippines.

Because the animal had never been studied rigorously, little was known about its life history, habitat, or biology. “We suspected the giant shipworm was radically different from other wood-eating shipworms,” says Haygood. “Finding the animal confirmed that.” Altamia continues, “Frankly, I was nervous. If we made a mistake, we could lose the opportunity to discover the secrets of this rare specimen.” The scientists were then faced with an interesting dilemma to answer the question…. why Kuphus is so unusual?

The answer may lie in the remote habitat in which it was found, a lagoon laden with rotting wood.

The normal shipworm burrows deep into the wood of trees that have washed into the ocean, munching on and digesting the wood with the help of bacteria. Unlike its shipworm cousins, Kuphus lives in the mud. It also turns to bacteria to get nourishment, but in a different way.

Kuphus lives in a pretty stinky place. The organic-rich mud around its habitat emits hydrogen sulfide, a gas derived from sulfur, which has a distinct rotten egg odor. This environment may be noxious for you and me, but it is a feast for the giant shipworm.

And yet Kuphus eat very little. Instead, they rely on beneficial bacteria that live in their gills that make food for them. Like tiny chefs, these bacteria use the hydrogen sulfide as energy to produce organic carbon that feeds the shipworm. This process is similar to the way green plants use the sun’s energy to convert carbon dioxide in the air into simple carbon compounds during photosynthesis. As a result, many of Kuphus’s internal digestive organs have shrunk from lack of use..

This work is an important part of research grants provided by the International Cooperative Biodiversity Groups program. The program helps researchers conduct projects in developing countries to find unique, novel compounds for future drug development, while building research capacity and conserving biodiversity in the host country.

Shipworm Video

Learn More About Giant Shipworms

The findings described here, led by scientists at the University of Utah, Northeastern University, University of the Philippines, Sultan Kudarat State University and Drexel University, will be published online in the Apr. 17 issue of the Proceedings of the National Academy of Sciences. Or, to learn more, listen to an interview with Margo Haygood on Scope Radio

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