I go to the Seattle Aquarium pretty frequently, mostly just to check out the Giant Pacific Octopus. If you start chatting with the volunteers there, they might tell you great stories about the octopus sneaking out of its tank and snacking on the nearby tidal exibit.
Adam Shostack sent me a link this morning to a TEDBlog post about a pbs clip of the Seattle Aquarium's octopus eating the sharks in the shark tank. The video shows the octopus take down a 3-4 foot shark.
I had to install RealPlayer to view this, but it was worth it.