We have far more then 6 senses. We have 5 sensory organs, but we can sense much more then 5 things. There are between 9 and 21 human senses, depending on how you define "sense".
And there are numerous that we don't have. We can't see ultra-violet without visual aid for example, which I think some forms of animals can.
Not percieving something, doesn't mean it doesn't excist. We cannot see cosmic radiation, we cannot see light waves, radio waves etc.
Here's a lecture from Richard Dawkins that I think you will love, where he speaks of human perception and the "middle-world" we live in.
http://www.youtube.com/watch?v=1APOxsp1VFw