Orangutans are great apes that live in tropical rainforests in Borneo and Sumatra. There are two types, the Sumatran orangutan and the Bornean orangutan. Orangutans are primarily arboreal and have long arms for swinging through trees. Males and females differ significantly in size, with males weighing around 100 pounds and females over 260 pounds. Orangutans are solitary and meet only to mate. They communicate through long calls and are known for using tools.

1. Robert Phan
ANTH 101
Prof. Robertson
April 1, 2015
Primate Research Paper
Orangutan (genus Pongo), member of the subfamily Pongines (Larsen 2011:176) is an
Asian species of great apes. They live in on the islands of Borneo and Sumatra in Southeast Asia.
There are 2 types of orangutan, the first one is called Sumatran orangutan (Pongo abelii) and the
second one is Bornean orangutan (Pongo pygmaeus). The word Orangutan means “person of the
forest” in the Malay language. It has an average life span in the wild between from 30 to 40
years. Orangutans are the only primarily arboreal great ape, which means that they live in trees
(Larsen 2011:17) and are the largest tree living mammal in the world. The other great apes do
climb, travel and build sleeping nests in trees, but they are considered semi-terrestrial, spending a
considerable portion of their lives on the ground. They have a large, bulky body about 2/3 the
size of the modern gorilla with long red-brown hair cover with most of their body, a thick neck,
very long, strong arms, short, bowed legs. An adult male orangutan has cheek-pads used to make
his head appear much larger than he actually is. The purpose was to look threaten or to look
attractive toward female. Since they are apes, they do not have prehensile tail, which is a tail that
acts as a kind of a hand for support in trees, common in the New World monkeys (Larsen
2011:180). Orangutans have an enormous arm span. It may stretch its arms about 7 feet from
fingertip to fingertip which is longer than its own height. They do have 4 long fingers and with
an opposable thumb just like us human. Their feet also have 4 long toes plus the opposable big
toe. This species demonstrates a significant sexual dimorphism which means that male and
female looks different. A male orangutan’s height is about 4 feet 2 and weighs 100 pounds. A

2. female orangutan’s height is about up to 5 feet 9 and can weighs over 260 pounds. Their dental
formula is 2/1/2/3. The orangutan only live in tropical rain forests. They mostly eat fruit,
especially one with sugar because those fruits make up to 80% of their diet. They can also eat
young leaves, shoots, bark, insects, honey and bird eggs. Their main activities occur during the
day such as finding food, which makes them diurnal. The orangutans’ residence patterns are
solitary because they usually live alone. One of the reason why they live alone because of their
daily eating habit. Starvation will be a huge problem because of food shortage if there are too
many orangutans live in one area since they consume lots of food. They only meet together for
reproduction purpose. When mating, the male and female orangutan stay together for only few
days. After that, the male goes away and the female stay with her offspring roughly about 7
years. Orangutans are very smart because they are well known of using object as tools. The
throat sac is used to make a very notable and recognizable call that echoes through the forest.
The “Long Call” is used to locate and advertise their presence to females or warn other males
away. Orangutans can be aggressive or not aggressive at all depend on the situation. If you
provoke them, they will try to kill you.
The brown-headed spider monkey (Ateles fusciceps) is a type of New World monkey that
lives in tropical and subtropical humid forests that are between 100 meters to 1,700 meters above
sea level which can be found in northwestern Ecuador. They have long, narrow limbs, hook-like
hands with no thumbs, black hair and a prehensile tail. They are 39.3 – 58.3 cm tall and weigh
about 9 kg. Brown-headed spider monkeys are diurnal so they moves around in daytime foraging
for ripe food, which is 83 percent of its diet. But when the dry season begin and fruits are hard to
find, they consumes leaves, flowers, seeds, bark, honey and sometimes small insects. Brown-
headed spider monkeys have a life span around 24 years and their residence pattern is multi-

3. male/multi-female so they live in a large group consists of 20 to 30 individuals. However, they
are very rarely all seen together and always to be found travelling, feeding and resting small in
groups of varying size and composition. Brown-headed spider monkeys reached the sexual
maturity at 4-5 years of age. The female gives birth to single offspring after a long gestation
period of 232 days. As an infant, the brown-headed spider monkey has pink face and ears but its
head turn brown as it grows older.