How do you say "What eats horses?" then?
Either "Hva spiser hester?" (ambiguous) or "Hva er det som spiser hester?" (unambiguous).
Eter? Isn't "eter" ether? Verb spise does not seem to have any conjugation form that becomes "eter"
It's also the present tense of the synonymous verb "å ete".
Less common in Bokmål, but still a valid option. You'll hear it in many dialects, and it's the default in Nynorsk.
? I thought it would be 'Hva hester spiser' ... am I wrong?
For questions that begin with "Hv-" words like "Hva..." the verb comes immediately after the question word.