What Is A Geoduck? The Ocean's Giant Burrowing Clam

Geoducks are harder to catch than you might think. Images courtesy of Geoduck Canada via Katie Lindsay

In Canada, a bountiful harvest sits beneath the sands in the form of a long, wrinkly clam that burrows into the seafloor. The geoduck, pronounced “goo-ey duck”, is perhaps one of nature’s most lewd creations (though arguably the penis fish still takes the crown) and is a giant among shellfish. Their shells, which are around 15 to 20 centimeters (6 to 8 inches), are outperformed by the geoducks’ massive siphon that when agitated stands to attention at around 1 meter (3.3 feet) in length. The geoduck’s impressive measurements make it the largest burrowing clam in the world.

What is a geoduck clam?

Native to the coastal waters of western Canada and the northwest United States, geoducks sit within a family of saltwater clams called the Hiatellidae. Their name is derived from a Lushootseed (language of the Nisqually) word, part of which translates to "dig deep", which refers to how far down you have to go to find them. Across the globe, it's also known as the elephant-trunk clam, mud duck, and king clam. Collectively, they are a “bag” of geoducks.

These bivalve mollusks are filter feeders and they are a much-loved species in British Columbia (BC), Canada, where locals credit the phallic animals for gifting their shores with clean coastal waters. They are also a source of revenue in the region, as each year 1,370 metric tonnes (3.03 million pounds) of geoducks are harvested for sale worldwide, with the largest markets existing in China and Hong Kong.

Geoducks have enormous siphons that can grow to a meter in length. Images courtesy of Geoduck Canada via Katie Lindsay

Where do geoducks live?

Geoducks (Panopea generosa), aren’t the easiest animals to harvest, found usually at a depth of 1 meter into the ocean floor. To collect them, solo divers must search for a geoduck show on the seafloor, which is when the geoduck pokes just the tip of its siphon out of the sand. Once located, the divers use pressurized water to clear the sand surrounding the clam. A lengthy process for one geoduck, but the harvesting method is favored because unlike trawling there’s no by-catch involved. 

As a long-living animal, with a maximum age reaching above 150 years, though one on record was said to be 168, they are vulnerable to overfishing and as such sanctions limit geoduck harvest to just 2 percent of the population in BC each year. You can age a geoduck in a similar way to aging a tree as their shells exhibit annual growth rings. 

Geoducks demonstrate sexual dimorphism and when mating season comes along the females release an astonishing 7 to 10 million eggs, which the males fertilize by broadcasting their sperm. Two days later, shelled larvae emerge from the eggs and will swim for a few weeks before assuming its position on the seafloor. Here, they dig in using a tiny foot and begin their juvenile lives as the world’s largest burrowing clam. Come adulthood, they lose their digging skills and will sit stationary in the sand simply extending and retracting their lengthy siphons to feed.

They were even once the stars of their own documentary, 3-Feet Under: Digging Deep for the Geoduck, the trailer for which you can view above.

So now you know what a geoduck is, perhaps there is one question that remains...

What does geoduck taste like?

Geoduck meat is apparently light and sweet in flavor, with a delicate crunchy texture that makes it stand out among other clams. So how on Earth do you prepare a clam the size of your arm? "Geoducks look like they might be challenging to prepare, but they are relatively simple," said Katie Lindsay from Geoducks Canada. "Geoducks can be prepared in various ways, but the most common way is served raw in thin slices. For sashimi-style geoduck, remove the geoduck shell and body meat (any meat inside the shell). The siphon of the geoduck (meat outside of the shell) can be blanched in boiling water for 30 seconds and then dipped in ice water. Peel off the layer of skin, cut the siphon in half lengthwise, and then slice it as thin as possible."

Bone apple tea, I guess.


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