This title is licensed for public performance by the MPLC umbrella license. Descend into the only habitat not directly driven by sunlight to discover some of the most peculiar creatures on Earth. Cut off from the rest of the world, animals living in caves have become specialists adapted to living with sparse food, complete darkness, and acidic conditions. The presentation tracks dangerous expeditions through largely unexplored subterranean regions of Mexico's Yucatan Peninsula and New Mexico to reveal unique underwater passages and crystal-lined caverns. (2 DVDs; one disc is teacher resources).