Strongylocentrotus franciscanus

The red sea urchin is the largest species of sea urchin, with a test (shell) diameter reaching up to about 25 centimeters (10 inches) and spines adding several more centimeters. Specimens can live for over 100 years, with some individuals documented at 200 years old, making them among the longest-lived animals on Earth. They are found along the Pacific coast from Alaska to Baja California.

Yes, the red sea urchin is commercially harvested for its gonads, known as uni in Japanese cuisine, which is prized as a delicacy in sushi restaurants worldwide. The commercial fishery is significant on the west coast of North America, particularly in California, British Columbia, and Alaska. Strict quotas and size limits regulate the fishery to prevent overharvesting.

Research has shown that red sea urchins can live for well over 100 years, with some individuals estimated to be 200 years old based on growth ring analysis. Studies by marine biologists, including work at the Scripps Institution of Oceanography, confirmed this remarkable longevity. They show little sign of age-related decline, continuing to reproduce throughout their lives.

The red sea urchin (Strongylocentrotus franciscanus) is significantly larger than the purple sea urchin (Strongylocentrotus purpuratus) and occupies a similar geographic range along the Pacific coast. Red urchins prefer deeper subtidal zones while purple urchins are more common in shallower intertidal areas. Both feed on kelp, but the red urchin is the primary species targeted by the commercial uni fishery.