Duality of terrestrial subterranean fauna

INTRODUCTION There are two time frames in considering terrestrial subterranean ecology, the classical period of 1832−1980 dealing with caves, and the modern period after the 1980s when a wide range of other subterranean habitats were also considered. After Schmidt (1832) published the first scientific description of an invertebrate well adapted for living in hypogean habitats, the beetle Leptodirus hochenwartii from the cave Postojnska jama in Slovenia, interest in studying subterranean biology and ecology increased enormously. Evidence of eyelessness, depigmentation, relatively long appendages and other convergent characteristics of subterranean animals launched the need for their ecological and morphological classification (Schiödte, 1849, 1851; Schiner, 1854; Racovitza, 1907). Since then, many modifications and refinements have been