Mollusks are one of the largest groups of invertebrates, with about 100,000 types in the world. The main kinds are snails and slugs, chitons, bivalves, and cephalopods. Readers will learn how mollusks sense the world around them, eat, defend themselves, and more. They'll learn about the life cycle of mollusks, and get an up-close look at land snails and pearl oysters.