These two siamang gibbons or apes are having a wonderful time playing and the one appears to be rolling around in laughter. Their formal name is hylobatidae syndactylus, meaning they are a subspecies from Sumatra. They are about three feet tall and weigh 17 to 28 pounds. The Oakland Zoo is in Knowland Park, California, and also has chimpanzees, baboons, squirrel monkeys, sun bears, and vervet monkeys.
