So why the kangaroo? Well, for starters, the animal disperses its energy differently than most animals. In a rowing crew, rowers take a stroke then rest as they slide back, positioning themselves for the next stroke. Kangaroos act much the same way, recovering energy while in the air, preparing for the next jump. When you begin to discuss robotics, energy preservation is a key factor in feasibility and ability. Finding any way to preserve it or more efficiently expend it is paramount.