Anatomy of a long-lived giant
The Pacific geoduck (Panopea generosa) is the world's largest burrowing clam. Native to the coastal waters of the North Pacific from Alaska to Baja California, it thrives in the soft, muddy seabeds of Puget Sound. An adult geoduck remains stationary for its entire life, buried up to a meter (3.3 feet) deep in the sediment. The only visible part is the tip of its massive siphon, which can stretch over a meter in length to the surface. This siphon contains two tubes: one draws in seawater to filter for phytoplankton and oxygen, and the other expels waste.
The clam's body is far too large to retract into its shell, which typically measures between 15 and 20 centimeters (about 6 to 8 inches). While the average weight is around 1.1 kilograms (2.5 pounds), some individuals have reached over 4 kilograms (9 pounds). This immense size and deep burrow provide excellent protection from predators. Once a geoduck is a few years old and has dug itself deep into the substrate, its primary threats are sea otters, dogfish, and certain sea stars that can attack the exposed siphon. This secure lifestyle is important in its extraordinary longevity.