Fog basking by the Namib Desert beetle, Onymacris unguicularis

THE Namib Desert along the south-western coast of Africa supports a sand dune fauna without counterpart elsewhere in the world1. The trophic base of the arthropod fauna is wind-blown detritus2. Aperiodic advective fog collection from vegetation3 or detritus4 is a possible source of water for diverse Namib animals. For the specialised fauna living in vegetation-less dunes, fog collection from detritus4, disturbed sand projections5, directly from humid air6, or from water precipitated on the body4,7, seem to be the only possible water uptake methods. Water uptake from saturated or subsaturated air, demonstrated for a few arthropod species6, is not a physiological capability of Namib tenebrionids already investigated4,6,7.