Phototaxis in monochromatic light and microspectrophotometry of the cerebral eye of the rotifer Brachionus calyciflorus

Abstract

The observed wavelength-dependent variations in the phototaxis of the rotifer Brachionus calyciflorus inform us only partially about the spectral characteristics of the sensory pigment of the eye, since these variations are also linked to the absorption spectrum of the accessory pigment(s).

• The absence of phototaxis between 420 nm and 500 nm is due to the lack of sensitivity of the sensory pigments at these wavelenghts.

• The absence of respose between 650 nm and 700 nm is due to a drop in the absorbance of the accesssory pigments, which consequently no longer play a screening role at these wavelengths.

• The existence of oriented responses between 350 nm and 420 nm and between 500 nm and 650 nmm, is due to the joint intervention of the two types of pigments at these wavelengths.