Who's keeping the ecosystem healthy? In any ecosystem, every species has a role to play. From towering trees and enormous whales to the smallest microorganisms, and from plants and fungi to animals and insects, each species is important to the overall health of the ecosystem. But some of those species play such vital roles that without them, the ecosystem is in danger of collapsing. These are called keystone species. In Keystone Species: Meet the Animals Key to Ecosystem Health and Biodiversity with Hands- On Science Activities for Kids, young scientists are introduced to several different types of keystone species from around the world as they discover the crucial roles these organisms play in their ecosystems. Meet the sharks, gray wolves, beavers, American alligators, bees, flying foxes, wildebeests, bison, and coral that all play a vital role in regulating an ecosystem.