Scientists find giant, fugitive clam famous as ‘the unicorn of mollusks’

For hundreds of years, biologists knew of a hulk shipworm usually from bombard fragments and a handful of passed specimens. Those specimens, notwithstanding being recorded in museum jars, had left to mush. Still, a shipworm’s sparse stays done an outsize sense on biologists. Its three-foot-long tubular shells — a shipworm isn’t technically a worm yet a bivalve — were so distinguished that Swedish taxonomist Carl Linnaeus enclosed a animal in his book that introduced a systematic fixing complement “Systema Naturae.”

And nonetheless no one could get their hands on a vital instance of a hulk shipworm, or Kuphus polythalamia. Unlike with other shipworms, named given they ate their approach into a sides of wooden boats, no one knew where a hulk shipworm lived.

“It’s arrange of a unicorn of mollusks,” Margo Haygood, a sea microbiologist during a University of Utah, told The Washington Post.

The medium of a world’s longest clam is a poser no longer. As Haygood and her colleagues reported Monday in a Proceedings of a National Academy of Sciences, a hunt for a hulk shipworm has come to an end.

Television news in a Philippines dealt a mortal blow to a shipworm’s near-mythical status. A TV hire aired a short documentary shred about bizarre shellfish vital in a lagoon. The uncover filmed a mollusks flourishing in a muck, as yet someone had planted rows of elephant tusks. As fitness would have it, a co-worker of Haygood’s in a Philippines held breeze of a segment. Researchers investigated the lagoon, where they plucked a live shipworm from a mud, slipped it along with some seawater into a PVC siren and shipped the animal to a laboratory.

“I’ve been investigate shipworms given 1989 and in all that time we had never seen a vital citation of Kuphus polythalamia,” Daniel Distel, a co-author of a new investigate and a executive of Northeastern University’s Ocean Genome Legacy Center, wrote in an email. “It was flattering fantastic to lift that tube out of a enclosure for a initial time.”

Distel carefully chipped divided during a hulk shipworm’s large shell. Smaller shipworms are obese pink, beige or white, as are many clams. Not a hulk shipworm. Its physique is black.

“To see this hulk gunmetal black citation was amazing,” Distel said. “On a one palm we was flattering vehement to see what it looked like inside. On a other palm it was a tiny intimidating to disintegrate this impossibly singular specimen.”

A mature hulk shipworm reaches up to 3 feet long, that means that when draped opposite a breadth of a twin bed, a clam would usually hardly fit. “It’s utterly heavy. It’s like picking adult a tree bend or something even heavier,” Haygood said. “The vital animal is usually magnificent.”

(University of Utah)

What’s more, a hulk shipworm hardly has a digestive system. “It’s not feeding in any normal way,” Haygood said.

The clam has a mouth and a tiny stomach, yet a gills are supersize. Living within those gills are bacteria. That’s not surprising for shipworms: The clams, as a rule, have symbiotic relations with microbes. Usually, though, a microbes assistance shipworms digest wood.

In a box of a hulk shipworm, a scientists found grains of sulfur packaged into a bacteria. The sea biologists think that, during some indicate in a shipworm’s evolution, a animal traded a wood-digesting germ for germ that feed off sulfur compounds.

The investigate “provides a fascinating instance of symbiont displacement, a phenomena we are usually usually commencement to observe some-more frequently in nature, interjection to advances in sequencing that have supposing us with a collection to uncover a evolutionary story of microbes,” said Nicole Dubilier, executive of a Max Planck Institute for Marine Microbiology, who was not concerned in a study. “What we are now saying is unexpected: symbioses are not as fast as we formerly assumed.”

The symbiotic arrangement between bacillus and hulk shipworm was identical to one found in deep-sea hydrothermal vents. Thousands of feet next a surface, over a reaches of sunlight, tube worms also get their nutrients from germ that devour sulfides. Despite their identical names, though, tube worms and shipworms aren’t tighten relatives. Tube worms are annelids — they’re tangible worms, like earthworms, not clams.

But a symbiotic germ in both deep-sea worms and a lagoon-living clams are associated to any other. “So this is a box of meeting evolution,” Distel said. That is, both the worms and clams independently arrived during a same conclusion: Housing bacteria inside their bodies was a excellent approach to stay nourished.

Haygood pronounced a participation of the sulfide-consuming germ suggested that a lagoon, perhaps filled with rotting timber or other organic matter, produced hydrogen sulfide.

The find lends support to a hypothesis proposed by Distel in 2000 about a origins of animals that live in deep-sea vents. In Distel’s theory, mussels that lived in wood and harbored a sulfide-eating germ competence have sunk to a vents. Far below, they flourished on sulfide expelled from a vents.

“Wood supposing an ecological bridge, assisting them to invade a vents,” he said. The find of a new shipworm indicated that shallow lagoons could have served as the location for a switch in germ types: First a timber served directly as food for clams. But once the clams began to take in a sulfur-loving bacteria, a timber supposing a source of a hydrogen sulfide for a microbes.

“This is an intensely singular instance where we were indeed means to find sincerely approach justification about how this sold symbiosis evolved,” in that a clams traded one form of germ for a other, Distel said.

Read more:

Now there’s a beam to penis worm teeth

What cancer in clams competence tell us about cancer in humans

‘Disco clams’ use their groovy flashing lights to quarrel off predators

Do you have an unusual story to tell? E-mail