Mammoth Cave National Park is home to over 70 threatened, endangered or state listed species. These species include birds, crustaceans, fish, gastropods, insects, mammals, mussels, plants and reptiles. The Federal Endangered Species Act of 1973 recognizes that many of our species across the United States have been lost and others are close to extinction. This act enables agencies to have the necessary means to aid these species in retaining their existance. Through education and restoration programs we hope to prevent further destruction caused by human impacts. Cave Life: More than 130 species are regular inhabitants within the Mammoth Cave system. These species are divided almost equally among three classes of cave life: obligate cave dwellers known as troglobites, facultative species which can complete their life cycle in or out of caves (troglophiles), and those that use caves for refuge (trogloxenes). Because of the region's biogeographic history, the tremendous variety of abiotic conditions, and the presence of key trogloxene species, the South-Central Kentucky karst has cave species and biotic cave communities among the most diverse in the world. The assemblage of cave fauna is diverse because both in-situ speciation and immigration of species that evolved in other cave regions has occurred.