Sites and Critters

Winter is coming

Winter is coming… well, it’s here really. January is a time of change and rebirth for many species in the seasonal seas of the Pacific Northwest. Perhaps this is true for none more so than the Giant Pacific Octopus, Enteroctopus dofleini. As the largest known octopus species in the world, these graceful giants are prominent inhabitants of Seattle’s underwater environment and serve as a captivating icon of local marine ecosystems for many Seattleites.

Despite their considerable size, Giant Pacific Octopus are thought to live only 3 years on average. And they’re semelparous… meaning they reproduce only once before they die. In their final year of life, the male presents a spermatophore to the female using a special tentacle called a hectocotylus. She carries the spermatophore around delicately for some time. Then, as winter descends, she establishes her clutch of fertilized eggs in the safety of her den. For months, she works tirelessly to keep them clean and protect them from predators. She doesn’t eat or leave their side. They remain her focus for the remainder of her life. With luck, she’ll survive to see the eggs hatch and her offspring swim off into the great blue world that awaits.

In the video below, you’ll see fertilized octopus eggs in a den we found last year under a fiberglass boat that was resting on the seafloor at a depth of about 50ft (in south Seattle). My video skills are admittedly horrific. Though the mother’s body isn’t visible in its entirety, you’ll see her flush the eggs with the end of her tentacle repeatedly (if you look very closely).

However, for a very sweet and far better visual exploration of an octomom’s final days, see the beautiful video by Drew Collins (below):

 

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Sites and Critters

Urban Dweller: The Giant Pacific Octopus

Giant Pacific Octopus in riprap den

Giant Pacific Octopus (GPO) in artificial boulder habitat  in Elliott Bay, Seattle

Coastal cities are not just home to high densities of humans. Octopus may also come to dwell in urban landscapes in large numbers.

This is what we’re finding in an underwater study we initiated earlier this year. We conducted video surveys at a series of paired, neighboring dive sites where artificial structures were abundant vs. sparse. The addition of artificial structures to the marine environment is a major part of urbanization in coastal cities. Artificial structures can consist of anything from sunken cars to old toilets to discarded garden gnomes.

Giant Pacific Octopus in some junk

GPO in south Seattle, in a den made out of an old iron hatch

Without revealing the full punch line (we’ve yet to submit our findings for publication), I can say that octopus densities tend to be higher at sites where there’s more junk. This may come as no surprise to long-time divers in the Puget Sound region. Scientists also have been aware of the use of artificial structures by octopus for some time. What’s so striking is the extent to which artificial structures appear to increase octopus abundance in even the most heavily urbanized locations.

Here’s a great video from UW research diver, Ed Gullekson, of octopus and several other critters that live just off of downtown Seattle, in Elliott Bay:

For more great videos from Ed “Sharkman” Gullekson, check out his Vimeo page here!

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