The Pacific geoduck can weigh up to 4 kg, with shells typically measuring 15 – 20 cm in length and siphons extending up to 1 m.
The geoduck (Panopea generosa) is widely distributed in the Pacific Ocean, offshore from the western coast of North America (from Alaska to Baja California, Mexico). They primarily feed on plankton, crustaceans found in open waters, and fish larvae. This species of saltwater mollusk can live for over 165 years. With its peculiar shape, the geoduck has a very long siphon, which is often considered a delicacy.
The Pacific geoduck is often considered a delicacy. (Photo: Natalie Fobes).
The name geoduck in English is believed to originate from the word “gweduc” used by the Nisqually Native American tribe, meaning “to dig deep.” They are the largest burrowing bivalve mollusks in the world. They inhabit depths of about 1 meter below the ocean floor.
As a bivalve species, the Pacific geoduck’s body is enclosed in a two-part hinged shell. They possess a foot that allows them to burrow into the sediment and anchor themselves. This mollusk feeds by siphoning seawater, filtering out plankton and nutrients, and expelling excess water through its siphon. The siphon has two openings at the end: one for taking in oxygen and plankton, and the other for expelling excess water.
Although the shell of the Pacific geoduck typically measures 15 – 20 cm, its siphon can extend up to 1 m. In the first 3 – 5 years of life, they can grow to a maximum weight of about 0.7 kg. On average, an adult weighs around 1.1 kg, but they can reach up to 4 kg.
Adult Pacific geoducks exhibit sexual dimorphism. They reach sexual maturity at around 3 years of age. Males can reproduce for over 100 years, while females have very large ovaries containing millions of eggs, laying 1 – 2 million eggs per spawning event.
While other bivalve species may move to avoid predators, geoducks react by retracting their siphons. They are preyed upon by crabs, sharks, sea otters, and starfish.
Geoducks are considered a delicacy in many parts of the world. They can be cooked or eaten raw as sushi or sashimi. Fishermen harvest wild geoducks or farm them, particularly in the state of Washington, USA. Some people believe they have aphrodisiac properties, possibly due to their unique shape, but there is no scientific evidence to support this.
