I have a list of Java updates in my add/remove programs box. Can I remove them all? What does Java do?

I have Java 6 Updates 2,24,3,5,7 and J2SE Runtime Environment 5.0 Updates 10,8 1nd 9 and 6 Updates 1. They are showing as rarely used so I don't know what they're for and why old updates aren't removed by new updates automatically.