We should note that this is for the worst kind of pedant only: the wrong kind. It's also important to note that the most correct of all forms (though also more archaic) is octopodes.

I noticed the author used octopodan. First time I think I've seen that word.

> But she was very significant to me, both as an individual and as a representative from her octopodan world.

It's a common adjective formation. Octopoda -> octopodan, compare to Mollusca -> molluscan.

What makes octopodes more correct? All the dictionaries cited preferred octopuses.

I have a friend who says pluralising "octopus" as "octopi" shows ignorance of three languages - English, Latin, and Greek. "Octopus" is of Greek origin and the Greek plural is "octopodes". The Latin plural is "polyporum" (the singular being "polypus"). The English plural is "octopuses" as we add "s" or "es" when pluralising.

'polyporum' would be genitive plural 'of the octopuses'. The more usual nominative plural would 'polypi'

On the other hand, you could say that not accepting "octopi" as a plural of "octopus" shows 'ignorance' of languages in general.