Humans have always relied heavily on animals. We have worshipped them, befriended them, sacrificed them, domesticated them, eaten them, hunted them, drawn them, and written about them. We have come to appreciate them, especially in their natural habitats, as an essential part of our world. They are creatures that deserve our respect and reward our curiosity. As intrinsic as they are to the ecological balance of our world, animals are under threat from their human admirers, and in dire need of our help. Habitat destruction spells disaster for many species, leaving them teetering on the brink of extinction. Only through a greater understanding of the fragile balance that exists between species and their habitats will it become possible for us to ensure the survival of our precious wildlife heritage. This encyclopedia present a wide-ranging survey of four major groups of living things and is carefully constructed to be read and appreciated by everyone with an interest in natural history. A team of internationally renowned authorities has provided the text for this publication.