Not who you're responding to but I must vehemently disagree. In English, which doesn't have a centralized governing body, the correct way of pronouncing/spelling something depends on your intention and expected audience. If your intended audience is English speakers then the correct spelling is probably octopi or octopuses, whichever you believe will cause the least confusion/distraction (surely it varies regionally).

However, usually my intention is to portray my unfathomably superior knowledge and intellect, so the correct spelling/pronunciation in this case is: octopodes (which I think he had listed but ironically got 'corrected' to 'octopuses').