Like a Leaf on the Wind, Watch How I Soar

here are a couple of articles on pupil shapes and their functions:

here's a section from the first article that explains the vertical pupil quite well:

"After regulating the pupil to the right opening for the environmental light, ambush predators must accurately gauge the depth to efficiently pounce on their prey. The stealthy vertical slit is the perfect adaptation, with two ways to gauge depth without moving: stereopsis and blur. Stereopsis, or depth perception, is where the brain perceives information from slightly different angles from the left eye and right eye to estimate distance. To test stereopsis on yourself, hold your finger out in front of your eyes. Close your right eye then your left eye. That shift in distance you see is stereopsis. The second method is blur, in which objects at different distances are out of focus. Stereopsis works best when shapes and contours are vertical and at a distance. Narrow vertical pupils give the sharpest image in this instance. Blur functions best for horizontal contours and close-in targets. Wide-open pupils are best in this method. The optimal shape to use both methods is vertical-slit pupils, which are narrow horizontally and wide vertically–which just happens to be the exact shape of cat pupils. The scientists were surprised to discover that predators with slit pupils were small and close to the ground. Among the 65 frontal-eyed ambush predators in this study, 44 had vertical pupils, and 36 had shoulder heights that were less than 42 centimeters (16.5 inches). Vertical pupils appear to maximize the ability of small animals to judge distances of prey. This is why domestic cats have vertical-slit pupils and their larger brethren, lions and tigers, have round pupils."

so in other words, vertical pupils are specifically helpful to small creatures more than large ones. I've had trouble finding any article that goes more into depth on why exactly that is, they all seem to just refer back to this point, that being close to the ground means vertical pupils have an advantage over round pupils, but they don't go into detail on what that means.

there may be more academic sources on that, but when it comes to fantasy worldbuilding I just don't think it's fully necessary to know the deepest biological details. an academic essay on the math behind vertical vs round pupils will certainly be important for the people who are studying how animal vision works, but maybe not so helpful for someone who just wants to know if they can reasonably give their elves vertical pupils lol.

intimidation is a tricky factor to work with. intimidation against what? a predator? other members of their species? other people? and how does it work? most animals with intimidation tactics go for the "make yourself big" or "bright colors suggest I am poisonous" options. some insects have false eyespots to trick the vision of predators into thinking they're looking at a larger creature. pupils might change shape during intimidation, but that probably isn't the only thing that should change.

they could have evolved from a smaller ground-dwelling predator and simply retained the vertical pupil (vertical pupils are round when relaxed, so it wouldn't be necessary for them to lose the vertical shape as they evolved) pupils getting smaller reveals more of the iris color, so perhaps this is part of the social communication/intimidation/courtship behaviors of their species.

I use shrinking pupils on my birdfolk, with the flashing of the iris color being both a tactic of flirtation and intimidation depending on the rest of their body language (and of course, feather fluffing is part of this too)

intimidation can include: making oneself look bigger (tall posture, raised back, fluffed hair/fur/feathers, wide stance, fully extended limbs, etc), wide eyes, wide mouth, loud sounds, and color changes or the reveal of colorful body parts that aren't normally so visible (like a dewlap, throat pouch, or some fur/feathers being extended to show off their full colors)

and many things used for intimidation can also be used to attract potential mates (like a flared peacock tail) sexual selection plays a massive role in the traits that get passed along and retained by the whole species. if having vertical pupils is a sexually appealing trait, it will likely remain in the species! especially if contracting the pupils to show off their verticality also reveals more coloration in the iris that potential partners find alluring, something that frames the pupil nicely to really show that vertical shape.

the vertical pupils of black skimmers seems to be an adaptation to cut the glare of light on water. in this way, it works similarly to polaroid lenses! light comes in at different angles, but polaroid lenses limit the angles of light that can come through them. vertical pupils negate horizontal light, only allowing vertical light to come into the eye. and the majority of light reflecting off mostly-horizontal water surfaces is of course going to be horizontal light. thus, the black skimmer, which flies low and parallel to the water in order to feed, has vertical pupils to see better in that lighting situation.

I'm draknkind. But I'm not Leafwing the frumious fantail.

I strongly feel like I should have hatched as a green and orange fantail this life but obviously didn't. "Leafwing" is what I call the drakn I should've, would've been. The hypothetical never-actually-existed drakn.

And sometimes I'll refer to my brain as Leafwing when I get, like, too drakn-brained

but I'm not Leafwing. I was supposed to be.

I'm Gideon. I used to be a weird shapeshifting creature in a weird digital world. I was supposed to hatch as a drakn in the universe where drakns exist, instead something went wrong and I ended up here. I identify as a 'demidrakn' which is pretty much just 'drakn plus'. Like I'm not less drakn, I'm 100% drakn plus other stuff.

This blog is for pure-drakn stuff. Leafwing stuff.

Okay so updates:

I believe I did incarnate as a drakn super briefly? Maybe not even hatching

I've stopped calling Me Now a demidrakn. You can check @digidrakncreature for current stuff

…. can I bend my claws??? 

you know how in the movies/shows their entire toes/fingers are covered in the claw-keratin? and can bend?

I can’t find a gif of this??