The Natural World Series explores different world regions and the people and other living creatures that inhabit them. The central focus of each book is the region's wildlife—its animals, birds, and insects—how and where they live, their foods, and their social, mating, and breeding behaviors. Each page of every title in this series is filled with full-color illustrations. The earth's ocean environment is at least as complex as any on land. Its living creatures range in size from whales to plankton—drifting plants and animals of nearly microscopic size.