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How do an orangutan’s long arms help it live in trees?

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An illustration of a female Bornean orangutan (Pongo pygmaeus) with long reddish-brown fur, hanging from tree branches with one arm extended upward and one leg hooked over a branch. A scale bar at the bottom shows lengths of 30 centimeters and 12 inches for size reference. — orangutan Female orangutans (*Pongo*) have the longest breeding interval of any mammal, giving birth on average once every eight years.

Orangutans are the largest arboreal animals, and their long arms are essential adaptations for navigating the forest canopy. While they typically travel by scrambling using all four limbs, their proportionately long arms—the longest of any great ape—allow them to occasionally swing through the trees using a form of locomotion known as brachiation.1

To support this arboreal lifestyle, orangutans possess several specialized physical features:

Hooklike hands: Their long fingers and palms, combined with short thumbs, allow them to securely grip branches while moving.1
Flexible joints: They have highly mobile shoulder joints and flexible hip joints, which provide the range of motion necessary to maneuver through the trees.21
Prehensile extremities: Like other large arboreal primates, they utilize four grasping limbs, which are more effective than two for maintaining balance and defying gravity in the canopy.13

These anatomical traits enable orangutans to move deliberately through the trees, where they spend more than 90 percent of their waking hours feeding, resting, and constructing sleeping platforms.1