What happens when you kill a squid for sushi purposes, then douse the tentacles with soy sauce just before consumption? The sodium in the sauce activates the muscles in the squid and the sucker dances right off your plate. Who's hungry?
On a side note, if you injected soy sauce into a fresh-dead squid and sent it to the bottom of the ocean for fluke or drifted it back to tuna, would you get the same effect? Food for thought.