After the accidental introduction into the Mediterranean Sea in 1984, Caulerpa taxifolia (Vahl) C. Agardh became invasive. Based on screening assays, it is assumed that a major factor for survival and/or invasion is a potent chemical defence system that produces toxic secondary metabolites. Various studies provide evidence that the main secondary metabolite in Caulerpa taxifolia, Caulerpenyne, is a bioactive substance with strong toxicological effects. These recent studies suggest the potential use of marine natural products synthesized by Caulerpa in pharmaceutical applications. This book investigates potential interspecies variation in secondary metabolite levels within the green macroalgae from the genus Caulerpa. The observed qualitative and quantitative decrease of Caulerpenyne under different conditions is tested in detail. In addition various extraction procedures are presented which enable the establishment of an efficient and reproducible extraction protocol. This book is addressed to everyone who is interested in marine natural products and wants to gain insight into secondary metabolites of the genus Caulerpa.