Marine sponges are responsible for more than 5,300 pharmaceutical products and some species have the potential to provide future drugs to prevent and treat important medical conditions such as cancer, a range of viral diseases, malaria, and inflammatory diseases. Nucleosides derived from sponges were the basis for the synthesis of Ara-C, the first marine-derived anticancer agent, currently used in the routine treatment of patients with leukemia and lymphoma. Marine sponges are the potential sources of many unique metabolites with anticancer, anti-inflammatory, antibiotic, antiviral, antimalarial, and immune or neurosuppressive properties. This book provides the taxonomy, common name, global distribution, habitat, diagnostic features and pharmaceutical compounds (along with their chemical structure and activities) of 450 species of marine sponges, accompanied by illustrations.