This is a video from the E/V Nautilus's remote operated vehicle Hercules disturbing a 'big earred' octopus, causing it to billow itself up like a circus tent in a defensive display in order to make itself look larger and deter any would-be predator. I think the concept of making yourself look larger to prevent getting eaten is a weird concept because in my mind now there's just MORE OF YOU TO EAT. Shoot, at first I thought you were just a snack, but you're a whole buffet. *tying plastic seafood bib around neck* You done goofed.
Keep going for the full video, compete with repeated billowings. Jeez, take a hint.
Thanks to Stephanie B, who agrees as far as the ocean goes, the deeper you go, the weirder it gets. That's actually true for a lot of things.