There are about 700 species of cephalopods (cuttlefishes, squids, octopuses and the chambered nautiluses) living throughout the seas of the world, some between the tides, others in the deep ocean, and yet others in the surface waters. Cephalopods are considered to be the most highly evolved marine invertebrates and possess elaborate sense organs, large brains and complex behaviour. This book examines that behaviour, summarizing field and laboratory data from a wide variety of sources in the first comprehensive account of the life of cephalopods in their natural habitats. It surveys the way they find prey and escape predators, how they reproduce, how they learn and how they communicate using complex body patterns. Throughout it emphasizes the gaps in our knowledge in the hope of stimulating more biologists to study these beautiful and fascinating animals.