Gibbons use their arms to swing from branch to branch, a way of moving called brachiation. What part of their bodies helps them do this?

Most mammals that live on land use their legs to get around. But the white-handed gibbon relies mostly on its arms. Using its long arms and strong fingers, it swings through trees with grace and speed. In fact, gibbons are so skilled at moving among the branches, they spend most of their lives in trees. They barely ever come down to the ground!
Gibbons use their arms to swing from branch to branch, a way of moving called brachiation. What part of their bodies helps them do this?
hooklike fingers
long legs
sharp teeth
Their long, curved fingers act like hooks to hold the animal's weight. Gibbons also have long arms (compared to their short legs) that rotate outward at their shoulder. Their wrists contain ball-and-socket joints so they can move in all directions.
When gibbons walk on a large tree limb or on the ground (something they rarely do) they do so:
on all four limbs
on their strong arms
upright on their hind legs
When gibbons walk, they usually do so upright with their long arms held above their head for balance.
When gibbons swing from tree to tree, they often soar through the air.
When gibbons are moving very fast, they can swing off one branch and propel themselves more than 30 feet (10 meters) before catching a new branch!
Gibbons have long tails like monkeys.
Many primates like monkeys have tails, but apes don't. Gibbons are apes, so they don't have tails.
Scientific Name: Hylobates lar
Habitat: evergreen forests in southeast Asia
Diet: mostly fruit; also leaves, flowers, and insects
Size: about 2 feet tall (about 60 cm)
Conservation Status: endangered
Lifespan: up to 50 years
Cool Fact: It can swing through the trees at speeds up to 35 miles (56 km) per hour.
Cool Fact: Hylobates means "dweller in the trees"