Bleaching of rhabdoms in eyes of intact butterflies.

The photochemistry of butterfly rhabdoms has properties that had been associated exclusively with the photoreceptor organelles of vertebrates. Noninvasive measurements of the absorbance spectra of rhabdoms in intact butterflies show that their rhodopsins are converted by light to metarhodopsins that decay from the rhabdom in the dark. A total bleach is possible because the first-order decay of metarhodopsin is considerably faster than the kinetically more complicated recovery of rhodopsin.