Figure 2.

Cross sections of rhabdoms in the dorsal rim area of the eyes of (a) S. satyrus (nocturnal), (b) S. zambesianus (crepuscular) and (c) Pachysoma striatum (diurnal). The rhabdoms have microvilli in only two directions. This is an arrangement that allows for an analysis of the polarization direction of light. Also note the difference in the size of the rhabdoms and the amount of pigmentation between the three species, both morphological adaptations to the time of activity. Scale bar (applies to all panels), 2 µm.