Is it a snake? Is it a fish? Is it an alien? No, it’s a first living giant shipworm that has been discovered by the scientists in the Philippines. This shiny black, three-foot long creature with a fleshy limb appears like an alien from a horror movie. But don’t be scared, it’s just a giant shipworm known as 'the unicorn of mollusks'.
This living creature, which has been found in the mud of a shallow lagoon, has never been described before. However, it’s known for over 200 years because of the fossils of the tubes as long as a basketball-bat inside which the creature lives.
“Although people have known [these animals] exist, they didn’t know the simplest things about them,” said Dan Distel of Northeastern University’s marine science centre and co-author of the study published in the journal PNAS. “It was a very mysterious organism.”
Decades ago, a description based on a museum specimen was made, said Distel, adding, the creature was not well preserved. “We think, among living biologists, anyway, our group are probably the only group that has seen living specimens,” he said.
With the Linnaean classification Kuphus polythalamia, the creature secretes a long tube made of calcium carbonate and it lives inside in it in the mud.
The tube makes a casing for the animal, including its head. “If they want to grow, they have to open that end of that tube, so somehow dissolve or reabsorb that cap on the bottom, grow, extend the tube down further into the mud, and then they seal it off again,” said Distel.
Distel further explains that the end of the tube is Y-shaped and surrounds two siphons. While one draws water, pushing through the creature’s gills, the other expels it.
Though the animal is known as a shipworm but it’s actually a type of clam. At its head, modified version of two clam shells can be seen, while its body stretches out behind.
“Its body has been stretched out through evolution so that it no longer fits between the two shells,” said Distel.
A YouTube video of a Philippine television news report helped the team find a clue to the whereabouts of the creature. The team members probed about the possible locations in the region and then they spotted a crop of the tubes in a lagoon replete with rotting wood.
Distel says they have kept the location secret fearing shell collectors may disturb the site.
The tubes were found by divers sticking upwards around 10ft below the surface. “That tube is anywhere from maybe 75%-80% buried in the mud,” said Distel. The team shipped about half a dozen to the laboratory, where the team tentatively opened one.
“It was really quite amazing,’ said Distel. “I didn’t even have any idea how to open it, but I thought: Carefully.’”
When the shipworm slipped out of the tube, the researchers were taken by shock and surprise because of its appearance.
“That colour of the animal is sort of shocking,” Distel said. “Most bivalves are greyish, tan, pink, brown, light beige colours. This thing just has this gunmetal-black colour. It is much beefier, more muscular than any other bivalve I had ever seen.”
Researchers were not only stunned by the discovery of this creature but also with its mode of survival.
“Gigantism is usually an indication of ample nutrients,” said Distel.
Unlike other shipworms feed on submerged wood with the aid of wood-degrading bacteria that live in their gills, the newly discovered shipworm has a tiny digestive system. The fact that it is enclosed in a tube points out that it doesn’t eat mud.
The researchers further revealed that the newly found creature relies of bacteria in its gills that use hydrogen sulphide in the water as an energy source. That energy turns carbon dioxide into nutrients for the shipworm.
Distel said this discovery throws light on the evolution of symbiotic relationships between sulphur-oxidising organisms and other creatures. It also establish a possibility that sunken wood might have played a role in driving the species in locations such as deep sea hydrothermal vents.
“To me it was almost like finding a dinosaur – something that was pretty much only known by fossils,” he said.
The discovery of the giant shipworm has been welcomed by Simon Watt, biologist, TV presenter and president of the Ugly Animal Preservation Society.
“It might well be monstrous, but that does not mean that it isn’t marvellous,” he said, pointing out that the creature has evolved to live in an environment that is also “pretty disgusting”. “If you are down living among murky dirt, then aesthetics are surely not your number one priority,” he added.
(Infographic by the University of Utah)