Ants are pretty hardy creatures, and a lot of them are quite acidic too. For instance the weaver ant pictured here has lots of formic acid which it can spray upon predators, so I would imagine that they are not a first choice meal.
However, if you`ve been keeping track of this blog, you may have seen the different spiders that mimic ants. However, mimicry can be defensive (to avoid predation by other creatures) or aggressive (to avoid detection by prey) and some of the mimics leave us wondering if the ant imitation is for predation of ants or for camouflage.
Now, to answer the question in the title – Do spiders eat ants? From these photos it is quite clear that spiders do prey on ants, even without the need for mimicry.
Technically they don't eat ants, they paralyse/kill it with their venom and suck out what is inside the ants exoskeleton, before they dump the body!