Photo: Two kangaroos hopping
The main characteristic of a kangaroo is its prominent hind legs and the use of hopping to move from one place to another (i.e. locomotion). At slow speeds, it also uses its tails as an extra leg.
The kangaroo has two powerful hind legs with long narrow feet, each with four toes. Its feet have soft pads, like that of a cat or dog. The first toe no longer plays an important role. The second toe is large and strong with a massive claw. This claw provides traction when it is hopping. The third and fourth toes are fused, covered by skin, and have two small claws. The kangaroo used these two smaller toes for grooming.
The answer is both yes and no. The kangaroo can't hop at slow speeds. So it uses pentapedaling locomotion. Pentapedaling is where the kangaroo uses its four limbs and it tail to move about.
Note: This article is about how kangaroos move, but the same principles apply to all macropods, except for the Musky rat-kangaroo, which has long hind legs but does not hop.
Kangaroos hop and jump by moving their hind legs together. They cannot walk by lifting and setting down each foot in turn like humans or cats and dogs do. Nor can they effectively move backwards.
As with all macropods, kangaroos have large, powerful hind legs and large feet specially designed for hopping. It has perfected this mode of locomotion to make it one of the fastest and most efficient methods of traveling over long distances. It is the only large animal that uses hopping as a method of locomotion. The kangaroo's legs are specially designed for hopping.
Using this method of locomotion a Red Kangaroo, for example, usually hops at a speed of about 20-25 km/h. It can also speed away at over 70km/h and leap over 3 meter obstacles when required. These kangaroos have been recorded travelling up to 20 kilometres at speeds of 40km/h without stopping for a rest. A single hop from a kangaroo can cover up to 8 meters! A human stride is only about 1 meter. Even an elephant can only manage about 2.5 meters.
Photo: Kangaroo's Achilles tendons
When a kangaroo hops, its legs compress, bringing its toes towards its body. This functions like a spring being compressed. Then its toes move away from its body, and it bounces up like a spring being released. The concept is similar to how a Pogo Stick works.
Photo: Kangaroo's Achilles tendons work like a rubber band
The actual mechanics of how this works is not what it seems. While it hops around, it actually gets its bounce from its Achilles tendons in the back of its legs. These tendons and associated ligaments act like giant stretching and shrinking rubber bands. When its legs compress, its tendons get stretched. Then the energy stored in the stretched tendon – referred to as elastic potential energy – together with contracting muscles start pulling the bottom part of the leg downwards, giving the animal a springing bounce back into the air. In this way, a kangaroo uses very little energy to move about. By using gravity and its weight to work its springy tendons, a kangaroo is estimated to use 40% less energy than a comparable four-legged animal.
Scientists suggest that the kangaroo has the most efficient method of locomotion of any ground animal in the world. At speeds above 6km/h, it actually uses less and less energy as its speed increases. At speeds above 18kph, a hopping kangaroo uses less energy than any other animal of equivalent weight. If a foxhound were to chase a kangaroo, it would consume twice as much energy and would tire out in less than 2 kilometres. The kangaroo, on the other hand, could go another 20 kilometres and still seems as fresh as when it started.
Kangaroos move extremely quietly compared to other animals. You would hardly notice a mob of kangaroos whooshing silently past you at top speed. An equivalent number of deer, which are similar in body sizes, would create quite a loud racket. The reason for this is that the kangaroo's soft padded feet, relatively small footprint, and the fact the only two feet touch the ground.
Kangaroos increase their speed by increasing the length of their hops – not the frequency of hops. When it wants to go slow it takes small hops. When it wants to go fast it takes large hops. All other animals increase the speed of each step, with only a very small increase in their stride.
The fastest kangaroo is the red kangaroo. It has been recorded at speeds of up to 70kph. At this speed each of its "strides" is as much as 8 meters apart. (The record is an astonishing 13 meters). Because hopping is super-efficient, it can also maintain this speed for a long time without exhausting itself.
Video: Kangaroo hopping
Because the kangaroo uses bi-pedal (two legs like humans) locomotion, it can easily pivot on one foot and rapidly change direction. It is claimed that it can make a 180 degree turn in a single hop. Four-legged animals with their relatively long bodies cannot turn as rapidly.
A Kangaroo can make very limited hops backwards when fighting. It cannot actually do so as a means of locomotion.
A Kangaroo cannot walk forward or backwards by moving its legs independently. The kangaroo can, however, move its legs independently it just can't do so for walking.
A kangaroo can move its legs independently when required, but while hopping kangaroos usually move both hind legs together. The independent movement of its legs occurs when the animal is turning while it is hopping when it places one leg slightly in front of the other to execute a turn. When it uses its feet in 'foot thumping' to warn other kangaroos of danger and when swimming.
The largest non-marsupial animal to hop is the rabbit, which hops using all four legs.
The red kangaroo can jump as high as 3m (3.3ft). It holds the high jump record.
At low speeds, however, a kangaroo is far less agile. Its super-efficient hopping legs let it down. (See next section to learn how a kangaroo moves at slow speeds).
Video: Kangaroo pentapedaling
Despite the kangaroo's reputation for gracefully hopping through the landscape, it actually spends more time moving at a more leisurely pace of below 6 kilometres an hour as it feeds and socialises with other kangaroos. At this speed, its movements are ungainly indeed. While highly efficient at higher speeds, a kangaroo's hind legs are cumbersome and almost useless at lower speeds. The kangaroo has adapted to this shortcoming by developing a fifth leg! Where is it, you wonder? It's the kangaroo's tail.
A kangaroo moves at low speeds by leaning forward on to its short front limbs, hoisting itself up with its tail and then shifting its hind legs forward. This method of movement is called 'pentapedal' (four limbs + tail) locomotion. Only the kangaroo does this. Recent research has shown that the kangaroo's tail with its 20 vertebrae, acts like a fifth limb fulfilling the role of a normal leg. In this role it is capable of generating more forward force than all of the kangaroo's other limbs combined.