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