By JAMES GORMAN
The signature gait of kangaroos is a marvel. As they hop, they seem to float along almost effortlessly on their large, springy hind feet, tail stretched out behind for balance.
A classic study showed that the faster they go, up to a point, the less energy they use.
But they also have a slower, walking motion that they use when they are feeding, moving only a few feet at a time to the next patch of grass. And for that, they depend on the tail not for balance or as a kind of crutch to lean on, but as a muscular, very important fifth leg.
Read the full story in the New York Times.