Looks like ChatGPT rewrites it anyway:

Q. Is the sentence "How many legs has an ant" grammatical?

A. Yes, the sentence "How many legs does an ant have" is grammatically correct. It is a question asking for the number of legs that an ant has.

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I think it is grammatical, it's just poetic? An expression like "Such a hunger to know how many stars has the sky" is not unusual to my ears.