lively bunch, reclusive, come in all sizes, from extra tiny, to back off quick, and a whole other complex octapoid lifestyle
I regularly interact with spiders, wolf spiders bieng my favorites by far, sometimes called jumping spiders, they are sight hunters and dont build webs, and seem to stay in a certain teritory for days or weeks, before moving on
Another one that we misunderstand a lot is virus. It looks like the typical second declension thing ending in -us. It is actually a rare categorization of word, the 4th declension.
But it is a common occurrence in languages that when rules are complicated and confusing that they get generalized to simpler patterns from elsewhere in the language.
Romance languages have done that to Latin too! I gave an example of opera being the plural of opus. A lot of romance languages have reinterpreted neuter plurals as feminine singulars, because of that -a suffix.
In the US, it is regional to the east coast, both north and south. It is also common in African American speech.
By that logic irregardless is also not really incorrect.
But if you want to sound more latin, octopus is a third declension noun, and those have nominative plurals that tend to end in -es, rather than the second declension which ends in -us for singular or -i for plural. Third declension nouns whose nominative form ends in -s also tend to change their root's final consonant when you change the suffix. (Eg. opus -> opera. That one doesn't end in -es because it's neuter.)
All this to say, the latin plural of octopus is octopodes.