Figure 2.

Spectral characteristics of retinal photoreceptors and ocular media in juvenile and adult Australian lungfish (Neoceratodus forsteri). (A) Normalized absorbance spectra of cone photoreceptor visual pigments. UVS, SWS, MWS and LWS refer to the pigments found in the ultraviolet-, short-, medium- and long-wavelength-sensitive cones, which have wavelengths of maximum absorbance (λ_max) at 366, 479, 558 and 623 nm, respectively. The absorbance spectrum of the rod pigment (λ_max 540 nm) is not shown. All pigments are found in juvenile lungfish (j), but the UVS cones are absent from adults (a). (B) Absorptance spectra of intracellular organelles and spectral filters. R, E and C refer to the red oil droplets, yellow ellipsoid pigment and colourless oil droplets in the LWS, MWS and SWS/UVS cones (spectra pooled), respectively. The absorptance spectrum of the yellow paraboloid pigment in the MWS cones of adult Neoceratodus (not shown) is almost identical to that of the ellipsoidal pigment in juveniles. (C) Normalized transmittance spectra of the combined ocular media (lens, cornea, etc.) of adult and juvenile lungfish. Note the increased absorption of shorter wavelength light by the ocular media of the adult. (D) Calculated quantal spectral sensitivities of the 4 cone types in juveniles and 3 cone types in adults, taking into account the spectral filtering effects of the intracellular spectral filters and ocular media on the absorption of light by the visual pigment in each cone type