A study out of SFU shows that kangaroos actually use their tail as a fully functional leg when they are grazing the land.
Max Donelan, an associate professor in the Department of Biomedical Physiology and Kinesiology, led the study on kangaroos’ unusual gait. Donelan explained that a kangaroo does “as much mechanical work with their tale as we do when we walk.”
Aided by postdoctoral fellow Shawn O’Connor, Donelan’s study focused on the awkward gait kangaroos have when they graze the land, which is unlike the “graceful hop” we picture them having when we think of the Australian outback.
Kangaroos graze with their tail planted on the ground, acting in combination with their short front legs and long hind legs. This motion is known as “pentapedal gait.” The tail acts as a leg in the sense that it pushes off the ground, rather than the front legs, in order to create the force that starts the cycle of walking.
Donelan, whose principal field of research revolves around humans and walking, explained to The Peak, “With humans, we have learned in the course of the past 15 years that a key part of the walking cycle is before your right foot comes in contact with the ground, you have to push off the ground with your left foot. This movement is really important in saving energy that is required for walking.”
Kangaroos’ unique anatomy restricts them from using their short front legs as a means to push off the ground; thus, their tail becomes key in this essential push needed to commence the walking cycle.
Donelan believes that studying the “pentapedal gait” of kangaroos, as well as the unusual gaits of other animals, sheds light on the general principles of biomechanical motion and offers insight into the solutions available to biomechanical problems.
Donelan noted, “A key aspect of covering this is the question: Why are Canadians studying this interesting, yet possibly irrelevant form of locomotion? What this really gets across is that it is helpful for us to understand the basic principles of locomotion, which works into the bigger picture of understanding humans.”
Donelan has also studied the movements of cats, shrews, crocodiles, elephants, and giraffes. As interesting as these animals are, Donelan’s research is not driven by the type of animal he gets to study; rather, he says, it is driven by the important questions and the insights that can be gained in order to better understand the biological movements of humans.
