Cat's stalking style is far from effortless

摘要

Stealth comes at a cost - at least it does for cats. They sacrifice energy-efficiency for their slinky moves. Humans, dogs and horses are highly energy-efficient walkers, and all walk with relatively straight, stiff legs, says Kristin Bishop, a biologist at the University of California, Davis. She wondered if cats, with their crouched gait, managed a similar efficiency. To find out, Bishop and her colleagues observed domesticated cats walking along "force plates", which measure the force exerted by each footfall. Combining these measurements with the speed at which the cats were travelling allowed the team to calculate how much energy they expended as they moved. They found that only 20 to 38 per cent of the energy expended as the cats walked was actually converted into forward motion. Dogs typically convert around 70 per cent of this energy.