Incredible Invertebrates. Did you know that most animals in the world dont have backbones? Learn more about invertebrates in this engaging nonfiction book. Readers will learn all about mollusks, arthropods, arachnids, and crustaceans while being stimulated from cover to cover with its detailed images and charts, intriguing facts, and informative text. This 6-Pack includes six copies of this title and a lesson plan.