Originally Posted by wjc
I think only a fish would know that answer for sure since they are looking at it through fish eyes.
What it looks like to us may have little bearing on it.
I appologize for another long reply but apparently my previous explanations are lacking in clarity.
If "only a fish would know that answer for sure since they are looking at it through fish eyes"
, means that we cannot know if a fish sees red; and if "What it looks like to us may have little bearing on it"
, also means that our color vision has little or no relationship to a trout's color vision; both are incorrect.
Form equals function. Biologists have examined the cones of trout, the organs that see color. They have 4 types of cones, one more than a human, but the UV cone gradually becomes non functional.
So mature fish have 3 sets of cones just like humans. The original 4 cones cover a slightly broader spectrum into the UV and IR. The cone that sees into the IR remains. Remember Diver Dan posted that IR light attracted a sturgeon? That is probably the reason.
Originally Posted by Diver Dan
I think Sturgeon can even see infared light. I was in an icehouse with a guy that had a camera down It was one with infared LED lights for use in the dark or deeper water. While I was standing there we saw a set of whiskers go by and some stirring of the silt on the bottom. The next thing we saw was this Sturgeon eye fill the TV monitor. It just froze there like it was mesmorized. ......... I have no idea how long it was there after I left, but it seemed to be hypnotized by it while I was there.
So if the cones of a trout are sensitive to the same color spectrum that we are, we can assume that the trout "sees" the those same colors - those colors stimulate the optic nerve. What we don't know for sure is how the fish "interprets" the color it sees. Regardless, the original question was is red tippet invisible, and the answer is clearly no. How it interprets a red tippet is what you don't know for sure.
That is precisely the reason I brought up population dynamics. I don't believe the all fish interpret it exactly the same. It may spook some and not others.
If you don't believe what I am proposing, consider the following. How do you know that when you and a friend look at a red paint chip, you both are seeing the same thing? You assume you both are, because the anatomy of the cones in your eyes are the same, so they presumably react the same. You also assume the occipital lobes of both your brains react the same way to the optic nerve signals and you "interpret" those signals in the same way. So you see the same color. However, that does not mean you have the "reaction" to that color. You may love it and he may hate it. That is the difference between anatomy and population dynamics.
For an in depth discussion of human vs fish color vision see:
"The three types of cones in the human eye each contain a photo-sensitive pigment that has the capacity to absorb a range of light wavelengths. Each cone is characterized by the wavelength at which maximum or peak absorption occurs. The three are as follows:
erythrolabe; peak absorption at 565nm; red
chlorolabe; peak absorption at 535nm; green
cyanolabe; peak absorption at 440nm; blue
Light wavelength is measured in nanometers and the visible spectrum ranges from 700nm (red) to 400nm (blue-violet).
Trout, on the other hand, have four receptors, and the four peaks are 600nm, 535nm, 440nm, 355nm.
The second and third conform to the green and blue cones in humans. The first is similar to the human red, but its sensitivity range includes longer wavelengths than humans. The fourth is outside the band of wavelengths visible to humans and is referred to as "ultra-violet". However, the fourth class of cones disappears by the time a trout is two years old."
3. The color red appears brighter than it does to humans, but quickly becomes black at greater distance.
Color Vision in Trout Eyes | Trout University
Bottom line - trout can see the same colors that we do, in fact they see a bit further into the infra red. So they actually see more red color and not less than us.