I suppose I should point out that the sea anemone functions quite nicely with a gut that only has a single opening - take food in, digest, expel remains from th

I suppose I should point out that the sea anemone functions quite nicely with a gut that only has a single opening - take food in, digest, expel remains from the same opening. We also have amoeba which ingest food through vacuoles. But yes, a through-gut would be impractical.