As soon as we enter the Singapore Zoo, near the entrance, we saw these cute Cotton Top Tamarin. They are free to jump from tree to tree but they dont venture far, I guess cause there's ready food over here.
The concept of the Singapore Zoo is that most of the animals are not locked up in cages all day, they have spaces to move about. Singapore Zoo displayed animals in naturalistic, 'open' exhibits, i.e. with hidden barriers, behind moats and plants, etc.