The phylogeny of the polarization compass

Fig. 2:

Comparison between the specialized ommatidia (POL-ommatidia) in the dorsal rim area of different insects. The schematic drawings show cross-sections through the POL- ommatidia (top row) and the regular dorsal ommatidia (bottom row). A characteristic trait common to the POL-ommatidia of different insect groups is the strictly orthogonal orientation of the microvilli (for functional significance see project The polarization compass pathway). Colors indicate spectral receptor type used for polarization vision; violet stands for UV.