The naming conventions for most things in One Piece seem directly influenced by real-world things. I think the correlations run a bit deeper than we’ve seen, though.
Devil Fruits are mystical fruits found throughout the world that, when consumed, provide the eater a special ability, depending on the type and variation of the Fruit itself. With only one notable exception (Marshall D. Teach), an individual can only acquire the powers of a single Devil Fruit.
Devil Fruits are categorized into three types/classes: Paramecia, Zoan and Logia. Let’s see the possible concepts behind these 3 types of devil fruit.
Paramecia is a term for a water-based microorganism. There are a few real-world likenesses with this organism that go hand in hand with certain One Piece tropes. Such as Haki being similar to Kappa particles.
Zoan is a classification towards animals. Zoan-type devil fruit fellas are animal-based. That’s straight-forward as it could possibly be. You could push for the Protozoa angle, which is a microbiology term, but it seems like it’d just be straight-up animals.
Logia is the plural form of Logion. It’s a term directly planted in being divine. Power from the gods, so to speak, usually destructive. Forces of nature.
I think there’s something big in the Paramecia area. The idea of Devil Fruit being a possible living organism that preys on hosts for symbiotic relationships seems neat as all hell. Also, whatever the hell Logia is. We really don’t know much about devil fruits, which seems like a huge plot point to me.
*Theory by bigapefellow