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... COOL! Mine was really sketchy too, but I got the idea. That's totally awsome, I would never imagine an octopus actually taking out a shark, I thought that for the most part they kept to themselves, and went after crabs and small fish, but this... wow, totally awsome.
That a GPO could kill the shark in question is no great surprise. Our most common shark here in the Pacific NW is the Spiny Dogfish (Squalus acanthias). According to my reference books the maximum recorded size for this species is 63 inches in length and 20 pounds in weight. If the Seattle Aquarium folks were moving it to a larger home the octopus was probably in the 40 to 50 pound range (IOW: about half grown). Further, the dogfish is usually a fairly slow moving shark, although it has pretty good sprinting ability, and is known to rest on the bottom some of the time. That sort of behavior would make it a pretty easy target for a motivated GPO. [As an aside, a local marine biologist once told me about watching a 3 foot dogfish being caught, killed, and partially eaten by a large Sunflower Star (Pyncnopodia helianthoides).]
What I do find surprising is that the GPO would bother with the shark. The Seattle Aquarium doesn't skimp on food for the exhibits and I'd have thought the GPO would have been sated on all the crab that was presumably made available. Obviously, the aquarium people must have thought the same. Maybe the GPO just likes a bit of variety in his prey/dinner.