Spectral Sensitivity of Single Photoreceptor Cells in the Eyes of the Ctenid Spider Cupiennius salei Keys

Intracellular recordings from photoreceptor cells of all eyes of the spider Cupiennius salei Keys reveal 3 groups of cells with spectral sensitivity maxima in the blue (480 nm), green (520 nm), and UV (340 nm), respectively. The blue and green cells show secondary peaks in the UV at 340-380 nm. In the posterior median, posterior lateral and anterior median eyes, the majority of photoreceptor cells are the blue and green cells in roughly equal numbers. In the anterior lateral eye, however, the green cells dominate. UV cells were only found in the secondary eyes and only once in each of them.