Oh, and by the way, just a quick bit about the Zhu Zhu hamsters: they tangle in long hair!
My daycare girl I watch brought one over one day and the ZZ hamster was 'crawling' in my daughter's hair and got tangled around the wheels. And of course anytime you move it the wheels move so I finally had to cut it out! Poor thing...so watch your fur babies if they have long hair!