Ridges on humpback whale fins help them move through the water more easily. By adding these ridges to windmills, people can make more energy with less wind. Find out more in Energy Technology, a title in the Designed by Nature series. Designed by Nature is a series of AV2 media enhanced books. A unique book code printed on page 2 unlocks multimedia content. These books come alive with video, audio, weblinks, slideshows, activities, hands-on experiments, and much more.