yes but crunches help you achive that ultimate chick magnet of EIGHT PACK ABS!!!!!!
please note i only said help
But they don't.
Ab definition, whether you have a two-pack, four-pack, six-pack, eight-pack, ten-pack, or just a slab of muscle over your abdomen, is based entirely on genetics.
Visibility of said abs is controlled almost
entirely by how much fat you carry over them.
Therefore the recipe for good looking 6/8-pack abs is good genetics and low BF%.
Crunches and situps, and what else have you do nothing. At least with heavy lifts and gymnastic skills you're building good core strength, and not just doing what can be equated to making your biceps
push.