With striking images of coral-reef inhabitants, this photo-essay introduces Project Seahorse, an international effort to protect and rehabilitate the Danajon Bank, a double reef off a Philippine Island where seahorses once flourished. Turner opens with a description of scientists on a night dive to measure seahorses and, in the same place, a local fisher releasing a seahorse he has caught, supporting the project’s efforts. In information-rich chapters and more narrowly focused double-page insets, the author explains the curious seahorse biology (males give birth), the development of Marine Protected Areas, the lives of local fishers and their families, the use of seahorses in traditional Chinese medicine and local efforts to improve these refuges. She concludes with the concept of the “Onion World,” in which every layer—fish, reef, fisher, community, nation and world—has an impact on the animal. Tuason, a noted Asian marine photographer whose specialty is the Philippines, seems equally adept at photographing the land and people and the underwater world. This is another splendid demonstration of the work of Scientists in the Field. (glossary, acknowledgements, resources, how to help seahorses acrostic, index) (Nonfiction. 10 & up)