Structure of a Kangaroo's Legs

While they are bipedal – having two legs – like humans, the structure of the kangaroo’s legs makes walking impossible. Kangaroos aren’t capable of moving each leg independently. Kangaroos can move in two ways. They can use their huge hind legs to hop, with the largest kangaroos capable of bounding 25 feet in a single bounce. Kangaroos who aren’t in as much of a hurry can move by using their large tail like a fifth leg. They put their smaller front paws on the ground and use their tail for support while swinging their back feet forward.

Kangaroos have most of the same basic leg bones as humans, but modified to allow them to hop. The femur, or calf bone, is short. The two bones in the lower leg, the fibula and tibia, are much longer. Kangaroos lack patellae, or kneecaps. A kangaroo’s ankle is unable to rotate sideways.

In order for kangaroos to have such powerful legs, they have large muscles attached with elastic tendons. The hind legs sport the largest muscles a kangaroo has. These muscles not only allow for kangaroos to move so quickly, but allow them to kick box. Male kangaroos will fight each other using their muscular legs and females employ them for self-defense. Stretchy tendons attach the muscles to the bone and provide power to the kangaroo’s hop. The tendons compress with each bound, releasing like a coiled spring and propelling the kangaroo into the air.

Punctuating a kangaroo’s big back legs are a pair of unique feet. Kangaroos have feet resembling other marsupials, where some of their toes are fused together. Kangaroos have four or five toes. If present, the first toe is extremely small, while the second and third toes are fused together. The fourth toe is much larger than the others, aligned with the lower leg and used as a springboard for hopping. Their smaller fifth toe supports the fourth by adding additional thrust for each hop.