The giant shipworm, Kuphus polythalamia, is not new to science. As Ben Guarino at The Washington Post reports, even Carl Linnaeus, the father of taxonomy, was aware of this three-foot-long bivalve back in the 1700s. But no one had actually seen it still alive. Researchers studied the creature from fragments of its casing and the mushy dead bivalve bodies that had washed ashore.
“It’s sort of the unicorn of mollusks,” Margo Haygood, marine microbiologist at the University of Utah tells Guarino.
But a television station in the Philippines recently discovered the disgusting unicorn, while making a short documentary about strange shellfish growing in a lagoon. A researcher in the Philippines saw the film and sent a message to Haygood, and she helped organize an international team to track down the mollusks, according to a press release. They found the elusive creatures barely peeking out of the mud of a stinky lagoon full of rotting wood positoned in rows like planted carrots.
“Being present for the first encounter of an animal like this is the closest I will ever get to being a 19th century naturalist,” says Haygood, who is first author on an article about the shipworm recently published in The Proceedings of the National Academies of Science.
As Nicola Davis reports for The Guardian, the shipworm lives in a tube of calcium carbonate that it secretes. At the top, it has a Y-shaped siphon. It sucks in water through one branch of the Y, circulating it through its gills and expelling it out the other branch.
When poured out of its tube, the critter itself is not the prettiest. Roughly three feet long, the limp, tubular creature sports a shiny black coloration. “That color of the animal is sort of shocking,” co-author Dan Distel of Northeastern University tells Davis. “Most bivalves are greyish, tan, pink, brown, light beige colors. This thing just has this gunmetal-black color. It is much beefier, more muscular than any other bivalve I had ever seen.”
According to the press release, the creature eats very little, if it eats at all. Instead, it uses the stinky hydrogen sulfide found in the muck to feed bacteria that live in its gills—a process that produces carbon to feed the shipworm.
The giant is quite different from another, smaller species of shipworm, a type of clam that burrows into wood, including the wood of ships. The researchers hope to look at how these bacteria transitioned from digesting wood to hydrogen sulfide. They think that this transition could help them learn more about the evolution of other similar species, like the tube-dwelling creatures at hydrothermal vents.
“Its bacteria are more plant-like than the symbionts of normal shipworms,” Haygood tells George Dvorsky at Gizmodo. “Although the giant shipworm is eating the food produced by these plant-like bacteria—like we eat the plants we grow—it is a far more intimate relationship than our relationship to our food.”
While some people in southeast Asia do eat regular shipworms, there’s no word on whether anyone has tried to cook up the stinky giant version yet.