Book excerpt: Speleobiology, the study of cave life, is a relatively new science. The diversity of species that live in caves, springs, and aquifers is just beginning to be documented, and much of the underground world has yet to be explored. The surveys of cave life reported in this book represent an important step forward in understanding the biodiversity of caves in Oklahoma and Arkansas. The project whose research led to the publication of Cave Life of Oklahoma and Arkansas began in the 1970s as a study of Ozark cavefish and expanded to encompass two states and involve a number of research topics and collaborators. The authors and their team donned snorkeling gear, cave suits, and climbing harnesses and descended into caves in Oklahoma and Arkansas to study, inventory, and photograph this hidden world. The result is a comprehensive checklist of the region's cave fauna, complete with descriptions of these rare animals' distribution and ecological niches. The cast of characters ranges from familiar and charismatic species, such as cave crayfish and gray bats, to rare and bizarre fauna, such as blind salamanders and cave dung beetles. More than 175 full-color illustrations include stunning, never-before-seen photographs (from the cameras of Dave Bunnel, Tim Ernst, and Danté B. Fenolio, among others)of cave animals--even some newly discovered species. The authors also address conservation of subterranean biodiversity, discussing not only threats to cave life such as invasive species, resource extraction, and habitat loss, but also current methods of preservation and protection, including legislation, land acquisition, people management, and cave gates. The book's appendices provide a comprehensive cave bibliography and checklists of subterranean animals for each cave. Speleology is critical to science. Subterranean organisms are key indicators of groundwater quality, and their adaptations can lead to advances in medicine. Cave Life of Oklahoma and Arkansas advances our knowledge of, and can thus help us save, subterranean ecosystems--among the world's last frontiers.