You know I've always read that they will but figured they wouldn't if you made them happy. Well I guess I was wrong. The other night I was getting in bed when I heard a thump and a weird flapping sound. I thought it was a damsel jumping out of another tank so I went and turned on the light and there the mantis was flopping around on the floor. Luckily I was still up and was able to save her and put a lid on the tank. But wow, I really couldn't imagine a crustacean jumping!