Fig. 3: Explanatory graphics.
From: Pygmaclypeatus daziensis, a unique lower Cambrian arthropod with two different compound eye systems
a Structure of an apposition compound eye, consisting of numerous identical units (ommatidia). b Ommatidium of a terrestrial, c of an aquatic diurnal arthropod. d cross-section of an ommatidium. Note that the blue-white pattern, if focused, results in a light blue signal. e, f Optical axes stay vertical to the lens centres. Note that the scanning acuity of parallel optical axes is much higher than the scanning acuity in a bent visual surface. Lower part of e Facets of the stalked eye and their interommatidial angle. Lower part of f While the eyes of early Cambrian arthropods are spherical, trilobites develop more straight visual surfaces for higher acuity. g Eye parameter p as depending on luminance. Red dot: p of the dorsal compound eyes of Pygmaclypeatus daziensis (Graphic changed after ref. 10).
