VISION IN CICHLIDS Optical quality and visual perception in Cichlidae (Pisces)
Spherical aberration
Chromatic aberration
Accommodation
Optical resolution Little spherical aberration Accommodation by movement of the lens (b) Optical relation: 1/f = 1/v + 1/b Focal distance f = 2,3 r (r is lens-radius) Image distance b = 2,55 r (mean vallue; Matthiessens ratio)
VERTEBRATE RETINA Rods & Cones Bipolar & amacrine cells Ganglion cells
PHOTORECEPTORS
ontogenetic cone size
Incompatability of photopic sensitivity & resolution
Spatial resolution
Retinal resolution & sensitivity Angular density: H = (2,55 – v). /360 } 2. D number / o Minimum separable = (H -1 ) 0,5 60 min of arc Unit photon catching ability (threshold value) V c = (2S d + S s ) 1,5
Colour vision
Photoreceptor absorption spectra
Spectral distribution in various aquatic environments (Levine et al., 1979)
Transformation parameters of double cones and cone mosaic
square or row mosaic
sympatric speciation
The End