Wow, it's amazing what the mind can create within dreams all right.

There's an online dream dictionary that I find very interesting and in regard to what the spider may represent it says this, in part - which may or may not be relevant for you:

To see a spider in your dream indicates that you are feeling like an outsider in some situation. Or perhaps you want to keep your distance and stay away from an alluring and tempting situation. The spider is also symbolic of feminine power or an overbearing mother figure in your life. Alternatively, a spider refers to a powerful force protecting you against your self-destructive behavior...

So there's a few things there.

Last night I dreamed my finger was bleeding and I was trying not to get blood on my pants. I might see what it means. Hmmm.