Tuesday, February 16, 2010

Do Elephants Really Run?



Seeing an elephant run may be as rare as seeing one fly. It turns out that instead of running in the conventional sense, they adopt a unique gait at speed, with the fore limbs trotting and the hind limbs walking.

Norman Heglund of the Catholic University of Louvain (UCL) in Belgium and colleagues built an 8-metre-long platform to record the downward forces created when an elephant pounded over it.

This allowed them to calculate the changes in an elephant's centre of mass (COM). In all, 34 elephants at the Thai Elephant Conservation Center in Lampang were walked slowly or "run" at speeds of up to 5 metres per second over the platform.

When most animals walk, their COM sways from side to side. This switches to bouncing like a pogo stick when they run, a motion that wastes energy. But the team found that an elephant travelling at speed keeps its COM at a constant height from the ground, even though its front legs bounce up and down in a trotting motion. The result is a pogo element to an elephant's motion, but no vertical shift in its COM.

John Hutchinson of the Royal Veterinary College in Hatfield, Hertfordshire, UK, who also studies elephant gait, questions whether it counts as running, as by some definitions all feet must be off the ground at the same time – something that does not happen with elephants.

Journal reference: The Journal of Experimental Biology, DOI: 10.1242/jeb.035436

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