An Old World monkey, it is an arboreal (one which inhabits or spends large amounts of time in trees or bushes) macaque, belonging to the Macaca genus, and has the scientific name of Macaca fascicularis. A native of the Southeast Asia. Also known, by other names, of Crab-eating Macaque or Cynomolgus Monkey. Adult males grows to a length of approximately 38-55 cm, the females are shorter than males. The arms and legs are comparatively quite short. The tail, which is longer than the body, grows to a length of 40-65 cm. The fur varies from, yellow-green, gray-green, or reddish-brown colour. A social animal, usually found in groups of anywhere between five to sixty members, they are highly intelligent and display a great variety of calls and facial expressions. They are the most popular Macaque species, used in medical experiments and studies. One such study, led to the development of the polio vaccine. The Long-tail Macaque is also part of the monkey space program.