VISION IN CICHLIDS Optical quality and visual perception in Cichlidae (Pisces)
Mar 26, 2015
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; Matthiessen’s 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)• Vc = (2Sd + Ss)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