The word “kangaroo” comes from the language of the Aborigines, Australia´s indigenous people. It basically means “I don´t understand”, which was the answer given to British navigator James Cook when he asked what the animal was. What a misunderstanding! These marsupials have a kind of rubber band in their hind legs. It propels them upwards with each jump. The faster a kangaroo bounces, the farther the animal is “catapulted” forwards, and the less energy it consumes.