The Geoduck Is The World's Most NSFW Mollusk

By: Kristen Hall-Geisler  | 
Geoducks (pronounced goo-ee-ducks) are the largest burrowing clams on the planet and they can live to be 100 years old. Underwater Harvesters Assoc./HowStuffWorks

If you've ever read the word geoduck, you probably assumed it was some kind of duck that enjoyed maps, maybe. Oh, if only. That's not even close to what a geoduck is. In fact, if you pronounced it gee-oh-duck, you'd be wrong, too. While a waterfowl who's into geography might be pronounced gee-oh-duck, the name of this saltwater clam is actually pronounced "gooey duck." And these are not gooey and not ducks.

So geoducks are actually the world's largest burrowing clam, averaging 2 to 2.5 pounds (0.9 to 1.1 kilograms) each. Unlike the giant clam, which is almost all shell, the geoduck's shell is small compared to its soft body. The word geoduck comes from a Nisqually Tribe word meaning "dig deep."


Digging Deep

The name is apt, as these clams bury themselves 2 to 3 feet (0.6 to 0.9 meters) down in mud, sand or gravel at the bottom of the ocean. At 48 hours old, the tiny baby clams have a foot that they use to dig into the mud. Once they're in, they're in for life. They're found in the northern part of the Pacific Northwest, from Puget Sound along the coast of British Columbia and into Alaska. Natural "beds" exist on many public beaches, but they are rarely visible except at very low tides.

As they grow, the siphon (the neck outside of the shell) and the mantle (the "breast meat" inside the shell), are used like gills and a mouth all in one. Siphons and mantles are common to shellfish, but in the case of the geoduck, they're too big to fit inside the shell. Way too big. They leave the mantle at the surface of the mud and burrow their shells deep down. Then they just eat and breathe and hang out for, oh, a century or so.


At about 15 years old, geoducks reach their full size. The shell seldom grows more than about 8 inches (20 centimeters) wide, but the geoduck's neck can grow to be more than 3 feet (1 meter) long. And they often live to be more than 100 years old — old enough that scientists count and measure the rings of their shells to assess climate change over the decades. The oldest known geoduck was 168 years old, and the largest, found in Discovery Bay, Washington, was more than 8 pounds (3.6 kilograms).

Digging In

Geoducks have been on the menus of local northwestern Native Americans for hundreds of years. They were typically eaten fresh or smoked. Their harvest of geoducks continues to this day, with native tribes holding treaty rights to half of the shellfish harvest in Washington state's Puget Sound.

boy holds his first geoduck
A boy holds his first geoduck (giant clam) with the hole from which it was dug behind him. Clam diggers are trying geoduck farms as well.
Aaron McCoy/Getty Images

The harvest of geoducks is tightly monitored and regulated to prevent overharvesting. But these shellfish are popular outside of the Pacific Northwest, and most of the clams are shipped to China. A single geoduck clam can sell for as much as $60 in Hong Kong, though prices as high as $150 aren't unheard of. The limited harvest and the high prices have led to the unlikely crime of clam rustling and shellfish smuggling. People are also giving geoduck farming a try, which is 100 percent less likely to end in arrest.


If you like shellfish, geoducks will taste familiar, if a bit sweeter and even crunchier than most clams. The siphon is the edible part of any clam, and you get a lot of it with a geoduck. To prep for cooking, cut the siphon away from the shell and the stomach at the base of the siphon. Remove the skin, then trim and thinly slice the siphon. The most popular way to eat geoduck is to lightly sauté it in a stir fry to preserve its texture and flavor. You can also eat it raw like sushi — or like the First Nations in the Pacific Northwest have been doing for generations.