Caves. Long marveled objects of human curiosity. Within the deep, dark recesses of the earth lives an entire ecosystem of creatures rarely seen by the human eye, some so deep and so small that they are practically undocumented in ecology books. Yet, karst ecologist Mike Slay is fascinated by this very hole in human knowledge. In the short video below, Slay discusses why other animals do not live in caves and his scariest and grossest moments while studying caves. Reporting done by Jorge Ribas of Discovery Earth News.