A pygmy marmoset carries its young at the rainforest theme zone of the Ocean Park in Hong Kong, South China, Sept. 4, 2013. Pygmy marmoset is the smallest monkey in the world native to the rainforests of the Amazon Basin in South America. (Xinhua/Li Peng)

A pygmy marmoset carries its young at the rainforest theme zone of the Ocean Park in Hong Kong, South China, Sept. 4, 2013. Pygmy marmoset is the smallest monkey in the world native to the rainforests of the Amazon Basin in South America. (Xinhua/Li Peng)

A pygmy marmoset carries its young at the rainforest theme zone of the Ocean Park in Hong Kong, South China, Sept. 4, 2013. Pygmy marmoset is the smallest monkey in the world native to the rainforests of the Amazon Basin in South America. (Xinhua/Li Peng)