Description Who's keeping the ecosystem healthy? In Keystone Species: Meet the Animals Key to Ecosystem Health and Biodiversity with Hands-On Science Activities for Kids, readers ages 9 to 12 investigate several different types of keystone species from around the world as they discover the crucial roles these animals play in ecosystems. Hands-on science projects and essential questions offer kids a deep exploration into predators, herbivores, ecosystem engineers, mutualists, and foundational species keeping our world healthy!