[2] It can be found along the western coast of North America, ranging from the Aleutian Islands to San Francisco Bay.

[4] This large clam can live for more than twenty years and grow to a length of 15 cm (6 in), with smaller individuals being nearly as high as they are long.

[6][8] It is clear that PSP-causing toxin levels are typically much higher in the summer months[9] though this does not mean the seafood is necessarily safe at other times.

[10] Risks also vary based on species[6][8] but seafood available for retail sale is required to meet the FDA standards.

[6] By contrast, the highest measured level of saxitoxin in the Pacific littleneck clam Leukoma staminea was 580 μg / 100 g according to this 1996 report.