The overall body appearance of orangutans is a large, bulky body, long arms, short, bowed legs, and no tail.

Orangutans are covered in reddish-brown hair with grey-black skin. Males will look like adult female orangutans until they reach maturity. At that point, males will develop large cheek flaps and throat pouches to show dominance and call out to females. Females usually stand a little under 4 feet tall and weigh about 80 pounds, while male orangutans stand 4.5 feet tall and weigh around 160 pounds.

Orangutans have hands similar to humans in that they have four long fingers and an opposable thumb. However, the resting position for an orangutan’s hand is with curved fingers allowing them to effortlessly hook onto branches. Additionally, orangutans can grasp objects without using their thumb by using the tops of their fingers against their palms.

The feet of orangutans are similar to their hands as their big toe is opposable, so they can grasp things easily with feet.

There are three species of orangutans (Sumatran, Bornean and Tapanuli), all found only in Borneo and Sumatra. They spend more time in trees than any other great ape so old secondary forests or peat swamp forests are ideal. Orangutans have also been found in grasslands, fields, shallow lakes, and more.

Even though fruit makes up 65-90% of an orangutan’s diet, they are still open to whatever is available. A study showed that orangutans in Borneo had consumed over 300 different food items over their life such as honey, insects, bark, and even small primates.

It is much easier for male orangutans to find willing female mates if they have developed their cheek flaps and throat pouches. Once they have mated, females will be pregnant for about nine months. Male orangutans will play no role in raising the babies unless he is an older offspring of the baby. The babies will never relieve contact with the mother for the first six months. After the age of two, babies will travel the tree tops holding hands with other orangutans known as “buddy travel.” Juvenile orangutans will begin moving away from their mothers after five years.

Their name comes from the Malay and Indonesian words “orang-hutan” which translates to “human of the forest.”

Most great apes are knuckle-walkers while orangutans are fist-walkers.

Orangutans are extremely intelligent and have been known to use tools for extracting insects or seeds. A 2008 study at the Leipzig zoo showed orangutans displaying understanding of costs and benefits of gift exchanging. They are the first nonhuman species documented to understand this.