How many octopuses are in Puget Sound? Census seeks to answer questions about the remarkable giant Pacific octopus.

The giant Pacific octopus (GPO) is the largest octopus species in the world—yet little is known of its biology and ecology. Nor is it possible to know exactly how many GPOs are living in Puget Sound. But, with volunteer assistance from the local dive community, the Seattle Aquarium has been working to learn more about our local GPOs since 2000 with our annual octopus census. Each October, Aquarium and local divers take to the Sound in search of GPOs. When they spot one, they take note of the water depth, den type, habitat, the animal’s size, if eggs are present, weather and water conditions, and more. The data collected, and the changes in it from year to year, provide insight into how these important animals use habitat and affect the areas they inhabit.

How many octopuses are in Puget Sound?

The census began as an informal affair, with sightings reported via email, phone call and, in one notable case, on a paper towel. It became more structured over the years. The most recent major change took place in 2016, when the census moved from January to October—and the Aquarium selected six sites for staff divers to survey each year, in addition to sites throughout the Sound visited by volunteer divers. Three of the sites are in octopus-protected areas; three are in non-protected areas. The hope is that, over time, we will gain insights into the stability of GPO populations in these areas.

The word “octopus” is from Ancient Greek, not Latin, so technically the plural is octopodes. But because the word has been in use in English for hundreds of years, it takes the standard plural: “octopuses.”

How many octopuses are in Puget Sound?

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