Before the fish was the tunicate—the marine invertebrate.
The inner layer of the tunicate is a tube that moves water (and nutrients) in and moves waste out.
This core idea, as Jon Zahourek points out in this video, is a core element of human anatomy, too.
The gut is not exactly a technical anatomical term, but it seems appropriate.
In Old English, guttas (plural) means “bowels, entrails.” It’s related to the Dutch word goot, meaning “gutter” or “drain.”
Gut to gutter … not a big leap.
Down at our core, the drain. Where would we be without it?
Down in our anatomical layers, the tunicate lives. It’s a fact. No gut instinct required.