Scientists Find ‘Phallic-Looking’ Clams At The Bottom Of The Ocean — And They’re Crazy About Wood

These phallus-shaped clams have a one-track mind and all they care about is wood.

Open clam resting on algae.
M. Maggs / Pixabay

These phallus-shaped clams have a one-track mind and all they care about is wood.

Deep on the bottom of the ocean, a peculiar type of clam spends its life into hiding, boring into the unlikeliest of things: derelict, sunken wood. Known as wood-boring clams, these underwater critters are one of the very few animals on Earth that can eat wood, together with termites and shipworms.

Because they live their life in the confinement of their wooden burrows, these strange deep-ocean dwellers have evolved a curious, “phallic-looking” appendage that allows them to breathe. Snuggled deep inside their cozy wooden homes, these unusual clams feel up the ocean with a long, barbed, tube-like organ called a siphon – which they stretch outward from their shell and dip into the water to capture the life-giving liquid and pull it into their gills.

While their comically-shaped siphons “might elicit a chuckle” – making the clams appear “pretty PG-13-looking,” as noted by Phys.org – they do, nevertheless, prove very useful at keeping these organisms alive. By pulling water into their gills, these organs allow wood-boring clams to extract the much-needed oxygen, providing a literal breath of fresh air.

Until now, science has only known of three genus groups of wood-boring clams. However, it seems that their numbers are a lot greater than originally thought, as researchers have just announced the discovery of three new genera, and one new species to boot.

The credit belongs to an international team of scientists led by Janet Voight, an associate curator of invertebrate zoology at the Field Museum in Chicago. After analyzing the morphology and DNA of wood-boring clam specimens collected from various places in the world – including the Atlantic Ocean, the northeastern Pacific Ocean, and the southwestern Pacific Ocean off of New Zealand – the researchers arrived at the conclusion that the deep ocean fosters twice as many groups of “phallic-looking,” wood-munching clams as previously believed.

“There’s not just one tree-cleaner-upper in the ocean, they’re really diverse,” Voight said in a statement issued by the Field Museum.

“We’ve now found that there are six different groups, called genera, and around 60 different species.”

The newfound genera of wood-boring clams have been dubbed Abditoconus (“hidden cone,” a reference to how hard it was to find the cones that cover the clams’ siphons within the wood), Spiniapex (“spiny tip,” for the barb at the tip of the clam’s siphon), and Feaya, in a token of appreciation for the Feay family, who supported Voight’s scientific research at the Field Museum.

Meanwhile, the new species – one that belongs to the Spiniapex genus – has been nicknamed gilsonorum, in honor of the Gilson family, celebrated inventors of scientific tools and avid supporters of the museum’s efforts.

While these strange aquatic animals certainly possess a distinctive and quite unforgettable look, what truly makes them unique is their diet. These phallus-shaped clams have a one-track mind — and all they care about is wood.

After going on the prowl for discarded timber on the bottom of the ocean, the intrepid mollusks take over what bits of lumber they manage to find and prepare to settle into their forever home.

“Imagine living at the bottom of the ocean as a tiny swimming clam; you either have to find a sunken piece of wood or die. You wouldn’t think there’d be that many kinds of clams doing this,” said Voight.

Once they spot the sought-after material, the clams penetrate into the soggy wood, boring a small chamber wherein they hunker down for the long haul.

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But their cramped accommodations serve as more than just shelter – they also provide food. When hunger strikes and it’s time to look for dinner, the clams simply flex their muscles and rock their shells against the wood, scraping off little bits of sawdust that they ravenously consume.

Munching on wood requires some strong digestive skills. Luckily, these little critters have just the trick – a special bacteria in their gills that help them digest wood shavings.

Their penchant for wood is also doing the ecosystem a great favor. Despite their tiny size — some of their shells are about the size of a pea even for adults — these mollusks often settle in large numbers, which allows them to quickly dispose of wood debris.

“We have no idea how much wood is at the bottom of the ocean, but there’s probably a lot more than we think,” Voight points out.

“After big storms, we estimate that millions of tons of wood are washed out to sea. What if these clams weren’t there to help eat it? Think how long it would take the wood to rot.”

The newfound genera and species of wood-boring clams are described in a paper published on Tuesday in the Journal of Molluscan Studies.