Non veni pacem mittere, sed gladium.
OK, Biologists. Which is it? According to evolution, are these colors supposed to attract a mate (presumably color blind ones), hide from predators or scare away predators? What is the evolutionary purpose? It's Ok if you don't really know. Just make something up. We are used to it.
Well, if that dude was coming at me, I'd run away! (Maybe I'm just not cut out to be a lady spider.)