Giant Spider Crab, probably a Giant Japanese Spider Crab (Macrocheira kaempferi), a lot of local aquariums have them, looks like that is where this pic is from.
There is actually a variety of these that show up on the beaches by me during the summer months, especially after a storm. Very creepy, makes yoy not want to be in the water. I've been told that ones by me aren't very tasty.