No, most spiders are not cannibals. Some species of spider will eat the male either before, during, or after intercourse. Outside reproduction, cannibalism is even more rare.
Most spiders are not cannibals. Only some of them are. The black widow, and crab spiders are cannibals. It is a sexual cannibalism. The male spider eats the female spider.
All spiders are not cannibals for the sheer fact that many species, including spiders, resort to cannibalism for survival. Just because some species of spider may be cannibals, others aren't.
