Two subspecies of the siamang may exist. The zoo featured one of the first births of a Siamang in captivity. Two features distinguish the siamang from other gibbons. The siamang eats mainly various parts of plants. Calls in the late morning typically happen when it meets or sees another siamang group. Other ape species include the white-handed gibbon and the siamang. Classically, all gibbons were classified in the genus "Hylobates", with the exception of the siamang. Hoolocks are the second-largest of the gibbons, after the siamang. Gibbon species include the siamang, the white-handed or lar gibbon, and the hoolock gibbons. The siamang can live to around 40 years in captivity. The siamang is the only species in the genus Symphalangus. The South East Asian exhibit combines Sumatran orangutan and siamang together. Besides that, living, big, and tall trees can support siamang movement. The siamang eats at least 160 species of plants, from vines to woody plants. The siamang has long, dense, shaggy hair which is the darkest shade of all gibbons.