Fig. 5
From: The use of the skylight polarization gradient in young sandhopper’s orientation
(a) Experimental set-up used in releases under the sun and natural sky (modified from7). A, upper closure of the bowl. B, Plexiglas bowl; C, goniometer; D, opaline Plexiglas screen; E, Plexiglas plate; F, aluminium tripod. (b) Schematic representation of the set-up used for experiments in the laboratory under the dome (from26 modified). The dome was illuminated by an external light source. The upper side of the transparent bowl was covered with blue, grey and polarizing filters. The sandhoppers are released in the transparent bowl; the directions were recorded by a video-camera from below.
