You're right! and I've known this but that distinction didn't come to mind as I was writing the post. It's not really relevant though, as my point was about how adaptable and surprisingly intelligent behaviours even these tiny, tiny creatures with barely more than a milliwatt (I'm guessing) to their name, can produce. And you know, and can be used in a similar way to either set union or intersection in natural language :)
Spiders are not insects!