Beyond red-orange color, orangutan's most prominent feature is size. Like all great apes, orangutans are large. Largest by far are adult males, reaching 220 lb in weight. Their strength is legendary, reputedly seven times as great as a man's. Adult females are half the adult male weight. The little ones weigh only 5 lb at birth.
Adult male also differ from other orangutans in having cheek pads, a great drooping throat pouch, and a distinctive "long call."
Orangutans, like all great apes, are designed for life in the trees suspended below branches, so their arms are longer than their legs. Orangutans are the only great apes that travel, sleep and eat in the trees, so they have exceptionally narrow, elongated arems and hook-like hands and feet for grasping branches. The other great apes, all from Africa, tend to travel on the ground by walking quadrupedally on their knuckles. When orhangutans travel on the ground, they walk either upright or quadrupedally on their fists.
Orangutans range today only on the islands of Borneo and Sumatra. They are not spread everywhere on the two islands. Their island distribution has led biologists to recognize two subspecies, Bornean and Sumatran. Sumatran orangutans tend to have red-orange hair, often whitish around the mouth and abdomen; Borneans tend to be darker, sometimes almost chocolate. Bornean adult males tend to have more robust bodies than Sumatrans as well as larger, differently shaped cheel pads, while Sumatran males have better beards. Sumatrans seem to be more social than Borneans.
>Orangutans are exceptionally long-lived. Their lifespan is estimated to be 35 to 40 years. Captive orangutans have reached 60. Orangutans have the longest immaturity of all the great apes, 9 to 12 years. Their immaturity has three stages of roughly equal length: infant, juvenile, and adolescent. Females are deemed adult with the birth of their first infant, around 14 to 16 years, and males with the emergence of full adult regalia - cheek pads, throat pouch, and long call - as late as 19 to 20 years.
Orangutans are frugivores, with 50 to 60 percent of their diet devoted to fruit. They consume a host of other foods as well, making a remarkable diverse menu of up to 400 different foods, including young leaves, sap, flowers, honey, shoots, stems, seeds, nuts, bamboo, fungus, pith, bark, termites, ant, eggs and invertebrates.invertebrates.
The greatest mistery surrounding orangutans is their largely solitary lifestyle. Solitude is unusual in primates, who are renowned for rich social lives. Mature males are the most solitary. They are so intolerant of one another that if they meet, they threaten each other by staring, inflating their throat pouches, long-calling, and shaking branches. If neither backs down, the face-off may escalate to hand-to-hand combat, sometimes to the death.
Females are less solitary, even semi-social. They normally live with their offspring, making what is perhaps the only stable social unit on orangutan society. Immatures are downright gregarious.
Orangutan's female pregnancy is just under 9 months long (230-260 days), and they give birth to a single infant at a time. In all this they are very like human females, except for the fact that they bear an offspring only once every 8 to 10 years. All this makes orangutans extremely fragile as a species; they reproduce so slowly that losses take decades, even centuries to replace. Orangutans never stoop to the impulsive and reckless behavior of chimpanzees. They are among the mildest mannered primates, gentle, laissez-faire, and normally peaceable.