Some spiders use their mouths like scissors to snip or trim their webs. They do this to "clean up" and remove/relocate old prey after they are done eating. My pet widow, Shelob, can be seen doing this here.

This is one of two huntsman spiders that have been living in my parents house for the past week. Mum left out a bottle cap of water for them in the bathroom so they can have a drink. I think he's cute.