Any color that we can see, it exists somewhere in some creature's skin or eyes or scales or feathers or fur.

Color is vital! It conceals, it communicates, it signals.

Not for every animal, but for most, color lifts a lot of weight. But not all color is the same. Some color is way more messed up than you'd think.

Hi. Welcome to Bizarre Beasts. A new show that is bringing you face to face with a very weird animal once a month.

I've been doing this the last year on Vlogbrothers and starting now it’s going to become its own beast.  Now, what we perceive as colors are the different wavelengths of light reflected off colored surfaces. And we can only see a small range of these reflected wavelengths. Our eyes translate the waves that are closest together as purple and the ones that are farthest apart as red with the rest of the rainbow in between.

And color is usually a double-edged sword. If you're using color to stand out, you cannot also use it to camouflage. The leopard cannot change its spots.

But some animals can. A number of isolated times in the history of life, different species have undergone some ridiculously complex adaptations to enable color change. So, there are a few different ways animals make color, not just one.

There is pigments, which are just chemicals that have color, bioluminescence, where animals create chemicals that actually make their own light, and microscopic structures. Sorry if that last one threw for a loop, but tiny enough structures can bounce light around in a specific way, so that some wavelengths of lights are absorbed and others are reflected. This wavelength-specific light scattering is why this butterfly is blue and also this blue jay.

Most color-changing animals change color by controlling the amount of pigment visible in their skin. Panther chameleons, and probably some other species, can do this and something even better. They can alter the space between nanocrystals buried in their skin.

This is structural color change! So, yeah, two different ways to affect their color. That's, like, ha, I mean, it's not like there could be a third, right?

Except one day, and we're asking how, scientists realized that certain areas of various chameleons fluoresce under a black light. And they don't do it with pigments, and they don't do it with their nanocrystals. Let's back up for a moment.

Most chameleons live in sub-Saharan Africa and Madagascar, but a few species are found in other places, including north Africa, Spain, India, and Sri Lanka.  And there are over 200 different species of them. They're diurnal and they mostly eat insects that they catch by shooting their insanely long tongues out at them. They range in size from almost three centimeters long to just over sixty centimeters.

And when an insect isn't enough, large chameleons will occasionally snag a bird for lunch. They have amazing eyesight and can move and focus each eye independently, and see both visible and ultraviolet light, hence the whole glowing under the blacklight thing. They're really just fancy lizards.

The whole color-changing thing is great, but also check out their weird heads. So many different crests and horn-things and ornamental bits. And they have very good grasping clampy claw-mitten-hands and feet, which are perfect for holding twigs or branches and also tiny swords.

They're just good-looking animals. I like to look at 'em. Look at 'em with me.

A chameleon's little skull-bumps are actually important enough to have their own name, they're called tubercles and in chameleons in the genus Calumma, the patterns of tubercles are different between species and the males tend to have a lot more of them than the females. And these are the structures most likely to glow under UV light. They do not contain an ultra-violet pigment.

Instead, they are actually bony protrusions from the skull, and in those spots, their skin stretches super thin like a skin window. A skindow. So then, UV light can shine through those little skin windows and onto their bones. which chameleons can actually see.

We can only see it under a black light, but chameleons can see it all the time. It's a third method for them to create color, one that is invisible to us, but is perfectly vivid to them, and one that doesn't use pigments or nanocrystals, but simply the natural properties of bone and collagen. When this was discovered a couple of years ago, they were the only vertebrate where this visible-from-the-outside-bone-glowing was a thing.

Now everyone's gotten out their black lights, and it looks like there's also a South African gecko and two pumpkin toadlets with glowing bones, as well. So, this might actually be more widespread in reptiles and amphibians than we currently know. As for why, well, we think that this, like the rest of chameleons' color-making systems, is used for communication.

Chameleons have REALLY good eyesight. They rely on visual cues to catch their prey and for communicating with other chameleons through their color-changing skin. They're also VERY territorial.

And because the patterns of tubercles are different from species to species, and the males are bumpier than females, it might be about signaling both what species you are and also saying "hello" to the ladies. These chameleons have evolved a way to take advantage of the fact that bone just happens to fluoresce under UV light and added that to their already impressive arsenal of color producing and color changing abilities. A toolkit that may not be matched in its variety by any other kind of animal.

The only kind of color creation they don't use is bioluminescence, at least not yet. Let's give 'em a few million more years of evolution and I bet they'll figure it out. Subscriptions for the Bizarre Beasts pin club are open again.

Here's one of the three versions of this month's pin. They glow in the dark! If you're already subscribed, you'll get July's two pins, the Vlogbrothers' man o' war and the new Bizarre Beasts' chameleon, in the middle of the month.

If you subscribed after the trailer for this show went up or after this episode, you'll get the chameleon in Mid-July. Starting in August, new Bizarre Beasts episode will upload the first Friday of every month, and if you're already in the pin club, you'll get your pin around the time the video goes live and you're automatically signed up for the next month. New subscribers can sign up for about 72 hours after a video goes live, which means right now and for the next 3 days you can sign up for the Bizarre Beasts pin club.

When you do that you'll get your first pin on the middle of the month, and the ones after that on the regular schedule. And remember profits from the pin club go to support our community's efforts to decrease maternal mortality in Sierra Leone.