I’ve been going to zoos for almost 30 years. I’ve rarely seen a sloth move, and when they do it’s usually not very much. My most recent trip however was the exception to the rule. He was very social, trying to grab peoples hands, and sniffing their cameras.
In this shot, it looks like he intentionally laid over the marmoset sign to say, “Look at me! I’m just as cute as they are!”