[ INTRO]
Today is a really special day for me and Squeaks.
We’re eating our favorite colors!
Squeaks really loves the color red, and my favorite is green.
So we had some green asparagus for dinner… and check out our dessert!
Don’t worry, Squeaks; we’ll eat it soon!
But first, take a look at it!
When you see a shiny, red apple… the red you see is just how your brain understands
the light bouncing off of it.
Your brain gets information about colors from a place at the back of your eye called the
retina.
The retina has two kinds of parts inside it that help you see: rods, which are mostly
for seeing when it’s dark, and cones, which see colors.
When the light in the room shines on the apple, some of it bounces off toward your eyes.
And then, the millions of cones in your retina get to work!
There are three types of cones: some cones that look for reddish colors, some that look
for greenish colors, and some that look for blueish colors.
When you look at a red apple, it makes the cones that like red get excited!
[Squeaks gets excited.
He really loves that apple!
Jessi holds it up again.]
Exactly!
When the cones get excited, they send a message to your brain – kind of like a secret code.
The code from your cones says, “These are the colors I saw!”
Most humans can see all the colors in the rainbow pretty easily, using all three types
of cones.
But not everybody has three types of cones to work with!
Some people are what we call colorblind.
That doesn’t mean they’re blind, and it usually doesn’t mean that they don’t see
colors at all, either.
It just means that instead of three kinds of cones, only two kinds work properly.
People who are red-green colorblind have a problem with some of their cones – either
with the ones that look for red, or the ones that look for green.
So to them, red and green don’t look as bright as they do to the rest of us.
Both colors look kind of dull, and kind of similar to each other.
So red-green colorblind people have trouble telling red and green apart.
The other main type of colorblindness is called blue-yellow colorblindness, which means someone
has trouble telling apart – you guessed it!
– blue and yellow.
Because they have a problem with their blue cones.
Other types of animals can have different numbers or types of cones.
Dogs, for example, only have two kinds of cones in the first place, so they see the
world a little bit like some people with red-green colorblindness do.
Red and green probably look more like shades of blue and yellow and gray to them.
So if you’re buying a dog toy … your dog will probably have the most fun with a bright
yellow or blue ball.
A red ball won’t look so great to a dog.
But what if you had more than three types of cones?
A few lucky people see the world through four!
We can’t imagine what the world looks like to them, but I’ll bet it’s pretty exciting.
And for some animals, it gets even more exciting that!
For example, a flower that looks just looks plain yellow to you might look totally different
to a bee!
Bees have three kinds of cones to see color, just like us.
But instead of seeing red, green, and blue, their cones look for green, blue … and something
called ultraviolet light.
That’s a type of light that’s invisible to us, but it is there.
And bees can see it!
It’s kind of like a trade … we can’t see ultraviolet, but we can see red, and bees
can’t see red, but they can see ultraviolet.
And to get bees to land on them, some flowers have not only the pretty colors that we see,
but other patterns, too, painted in the ultraviolet light that bees can see, and we can’t.
To a bee, some flowers that look plain yellow to us actually look like a big target sign!
Some animals can see even more.
A type of animal that lives in the ocean called a mantis shrimp can have not three … not
four … but twelve or even sixteen different kinds of cones!
A few of those cones are just for seeing ultraviolet light.
We’re still learning what the world looks like to them, but if it looks this colorful
to us, with our three kinds of cones, just imagine what the mantis shrimp see when they
look at it!
Now, I think it’s time to finally eat this apple!
Thanks for joining us!
If you want to keep learning and having fun with Squeaks and me, hit the subscribe button,
and we’ll see you next time here at the Fort!
[ OUTRO ]