Good morning John on this, the 6th day of Pizzamas, I would like to introduce you to the manul or Pallas's cat. It's a wild cat that is roughly the same size as Cameo, my cat. But while it may look similar they are NOT. Spread across Tibet, China, Pakistan, India, Mongolia, Iran; these solitary grumpy temperamental cats eke out a living on small rodents and birds, keeping warm with the longest hair of any cat, hunting not through speed but through stealth, with fertility windows as short as one day per YEAR! But the thing that makes them so cute is what I wanna talk about today. Their eyes.

And you may be noticing that this cutie is a little less cute than the other manuls I've showed you so far. That's because I photoshopped house-cat eyes onto it! Here's the real boy! There's somethin' about those eyes!

We've gotten used to the eyes of our cats but they are a little bizarre. These vertically slitted pupils are complicated mysteries that have evolved separately not just in cats but in foxes, alligators, snakes, even some birds and sharks. And not all cats have these vertical pupils. Big cats don't have them but most small cats do and the European Lynx, which is of moderate size, actually has intermediate pupils.

And animals that have vertical pupils tend to have a few things in common: they're all hunters, they all deal with low light conditions, and they're all ambush predators. But Pallas's cat fulfills all those conditions. They're low light ambush predators. So how did they end up with these adorable, relatable eyes? I don't know, and neither does anyone, but I found this whole thing fascinating so let's walk through it.

There are 3 theories as to how vertical pupils help ambush predators.

First, vertical pupils rely on a curtain of stranded muscles to contract while circular pupils rely on a sphincter. Yes, you have sphincters in your eyes. And that more complex musculature allows them to contract and expand more. But, as the loris has shown us, this is not a hard and fast rule.

Second, we have distance judgement which is, as you might expect, pretty important for an ambush predator. And then are 3 ways animals use sight to tell how far away something is. The first is parallax, where objects farther away appear to move more slowly than objects close up. The second is binocular stereopsis which is the fancy way of saying normal depth perception when two eyes feed the brain slightly different images that are interpreted into a three-dimensional image. But last and least noticed is blur. When you look at something, especially something fairly close up, things closer to you and farther away from you from that point appear blurry. And when you're close to the ground, like a small cat or a snake, this matters more because you're closer to your prey and thus the depth of field is shallower. Vertical pupils seem to conserve horizontal blur, which animals use a distance judging technique, without sacrificing the vertical contrast necessary for stereopsis.

Now the third theory is a little harder to wrap your head around cause it involves optics. But basically if you want to focus on something close up with a really wide aperture, like if your pupils are super dilated cause it's dark, the ability of the lens to focus kinda breaks down. Different wavelengths of light, so different colors, pass through the lens medium at different angles so the image will never be sharp. To get that sharp image some animals, including cats, have actually evolved to have lenses with focal gradients. The middle optimized for green wavelengths, and then red, and then blue. This works? But if you have a circular pupil then when you contract, the area of the lens optimized for blue gets completely blocked. A vertical pupil on the other hand, preserves all of the color optimization.

Now as is often the case when it comes to how animals perceive the world, we're not 100% on any of these things, but we do know that with it's lifestyle a vertical pupil would be advantageous to Pallas's cat. So their adorable pupils, it turns out, are a mystery! AN ADORABLE MYSTERY! They shouldn't be there! But they are! So love it!

The manul, or Pallas's cat, is the Bizarre Beast of this month and I have great news: the Bizzare Beast pin club is opening back up just until the end of Pizzamas!. So if you want this Pallas's cat pin, which is very good, you can join right now! You will also get another pin every month with a different Bizzare Beast and information about it on the card. And there are more Bizzare Beasts on the way. Pizzamas also continues! John, I'll see you on Tuesday.