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Old 11-23-2012, 08:20 PM
overmywaders overmywaders is offline
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Default Re: Does blue excite the trout?

silver creek,

You said:
Quote:
The UV cones disappear as the fish matures so adult trout have exactly the same green and blue vision that we have. Adult trout do NOT see into the UV and are not sensitive to UV.
Where do you get that information? Most fisheries biologists acknowledge that the dorsal temporal zone of the trout retina still retains UV specific cones after smoltification.

Further, as Inigo Flamarique, who believes that trout lose all but a small percentage of their UV-specific cones at smoltification, wrote:
Quote:
DOES THIS MEAN THAT THE TROUT THAT IS A SMOLT AND OLDER DOES NOT SEE UV LIGHT? NO, EVERY VISUAL PIGMENT ABSORBS IN THE UV REGION OF THE SPECTRUM BUT ITS PEAK ABSORBANCE MAY NOT BE IN THE UV REGION OF THE SPECTRUM (SEE TYPICAL CURVES IN CHENG ET AL. 2006. J COMP NEUROL). BECAUSE THE LENS OF SALMONID FISHES TRANSMITS WAVELENGTHS IN THE RANGE 320-800 NM, ANY WAVELENGTH IN THE UV (320-400 NM) WILL BE SENSED BY THE BLUE, GREEN AND RED VISUAL PIGMENTS, ALBEIT THE SENSITIVITY OF THESE PIGMENTS TO UV PHOTONS WILL BE LESS THAN THAT OF A UV VISUAL PIGMENT. SO THE OVERALL SENSITIVITY OF THE SMOLT TO UV LIGHT (<400 NM) DECREASES DRAMATICALLY BUT IT DOES NOT MEAN THAT THE ANIMAL CANNOT SEE UV LIGHT. THE MAIN SENSORS OF THE UV LIGHT WILL NOW BE THE BLUE CONES (WHICH HAVE THE PEAK ABSORBANCE-LAMBDA MAX- NEAR THE UV PART OF THE SPECTRUM).
Humans have yellow pigmentation in the lens of their eyes to absorb UV and protect the retina. Trout lack this, so they inevitably receive UV; however, they have stem cells that regenerate any cones "burned out" by UV light.
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Reed

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