07_2025_REELLIFE_digital - Flipbook - Page 24
you get white. White
light is what daylight is all
about. Run that white light
through a prism, and you
get a display of the rainbow.
Most colors that are visible
are a blend of other visible
colors.
DUDE: Let me stop you right
there. You used the term
"visible." Are there colors
that are invisible?
KOKANEE: No. And I guess I
have to make an admission
that you humans and
we fish actually have
something in common.
We are both vertebrates,
and we have vertebrate
eyes. Within our eyes are
structures that connect
our eyes to our brain. We
both have corneas, and
attached to these corneas
are both rods and cones.
Although we have them in
different proportions, these
rods and cones operate the
same way. Simply stated,
rods help us differentiate
between light and dark,
while cones take care of
visible color detection.
Color is only a visible
concept. If you put all of
the visible colors together,
When you look at that
rainbow, the colors are
always displayed the
same way. That is because
visible colors have specific
wavelengths. Wavelengths
are measured by frequency.
Frequency can be thought
of as a way to measure
how long or how short
the wavelength is. In the
visible spectrum, red has
the longest wavelength,
whereas violet has the
shortest. All of the other
visible colors are in
between.
DUDE: OK. But how does
water eat light?
KOKANEE: It eats light by
wavelength frequency. As
you descend the water
column, the longest
wavelengths are eaten first.
That would be the visible
color red. Go a bit deeper,
and you also lose the visible
color orange. Go deeper,
and you also lose the visible
color yellow. The very last
visible color to get eaten is
violet. After that, the water
is black.
DUDE: I guess that black is
the absence of light.
KOKANEE: Technically,
black is the absence of
visible light. There are other
wavelengths out there that
you might understand and
feel the effects of, but their
wavelengths are outside of
the visible color spectrum.
DUDE: I hear so much
about UV light. All of the
manufacturers want me to
buy their stuff because it is
"UV."
KOKANEE: Here is where I
get to "see" how much you
have been paying attention.
"UV" is short for ultraviolet.
It is called ultraviolet
because it is in that part
of the spectrum that is
beyond violet. It has shorter
wavelengths than violet.
DUDE: But if UV light has a
shorter wavelength than
violet, then that means that
it is not part of the visible
spectrum.
KOKANEE: Exactly.
DUDE: So what about the
claims that fish can see UV
light?
KOKANEE: That claim is
nonsense. Go back to our
discussion of the vertebrate
