How anteater eat ant?

The same way they eat anything else. You may find the notion disgusting, but that's more a sign of the culture you've been raised in than anything else. Some people eat grubs, slugs, snails, insects larger and much "juicier" than ants, raw oysters, raw fish, raw beef, the salivary glands of sheep, chopped up lungs mixed with oatmeal... ants aren't even close to the top of the "ewww, that's gross" list.