This website spends a lot of time talking about octopus communication. Much of it is wrong, and some of it is a sort of new-age psychobabble. Since I've written a science fiction novel about future intelligent octopuses (who have along the way dropped their "loner" habits), some of this was thought-provoking for me, and a couple of aspects paralleled approaches that I took. You may find it interesting. I wouldn't be surprised if this had been posted here before. It contains a word unique to this one paragraph — "circoliveral" — and the only hits on that word are to many copies of this writing. Skip past the bit about the octopus's testicles being located in its head.