Orangutans belong to a single species known as Pongo pygmaeus categorized into two subspecies: P. p. pygmaeus of Borneo, and P. p. abelii of Sumatra. Orangutans have specialized upper limbs adapted for suspensory locomotion but are quadrupeds when on the ground. Standing 1.25-1.5 m (4 - 5 ft) tall, Orangutans have an arm span of about 2.25 m (7.4 ft). Adult males weigh 50-90 kg (110 - 198 lbs) and adult females 30-50 kg (66 - 110 lbs). They have bulging foreheads, protruding snouts, thin lips, and small ears. Orangutans have coarse, thin coats brownish-red in color, though P. p. abelii has slightly lighter coloring. Primarily frugivores, Orangutans also consume leaves, bark, and bird's eggs.