The sponge has attracted attention as one of the first animals to evolve multicellular organization. The sponge also interests scientists because it provides excellent research material in molecular phylogeny, allowing the process of animal diversification to be probed at the molecular level. Additionally, researchers have discovered in sponges certain bioactive substances with unique antibacterial and anticancer properties of great interest in medical and pharmaceutical science. Sponge Sciences presents the most up-to-date information on all areas of sponge research, with emphasis on taxonomy, molecular evolution, developmental biology, and natural products chemistry, as well as the biology of freshwater sponges. It also provides new findings in the morphology, cell biology, physiology, ecology, and biogeography of sponges. The papers compiled here are contributed by world-renowned sponge scientists.