Eyes

[Tundra]

So, i'm designing an alien character, who will be very humanoid, but that's another story. I think one of the main differences between him and humans, externally, will be his eyes. I want to move beyond having purple eyes, unless someone can think of a biological reason for eye colour? Is there one?

Also, different types of pupils. Cats have slits, goats have sort of rectangles, hippos have T shaped pupils... I know that hippos have eyes like that so it works like a periscope when they're half under water. What are some other types of pupils (imagined as well!) that have a reason for their shape?

What other eye differences could there be? He'll have access to contact lenses.

[AXJ]

How about.... they come from a world where the atmosphere doesn't filter UV or IR as well, so their eyes have evolved a sort of changable wavelength filter that blocks IR/UV during the day, but at night it clears to let them see the full spectrum?

Perhaps a second (inner) set of eyelids, again maybe as a protection from their sun or other climate conditions? And they have to be careful to blink REALLY FAST when they're around humans, lest it be noticed? Or maybe that's a reason for them all to wear crazy, big sunglasses all the time?

[melydia]

unless someone can think of a biological reason for eye colour? Is there one?

Now you've got me wondering. I mean, yes, we all know that our eyes are the color they are because of genetics, but I honestly have no idea why eyes are brown, blue, green, or hazel in the first place. Why doesn't anybody have yellow or red eyes, for instance? Unfortunately, I'm not even sure what to use as a search query.

Also, different types of pupils. Cats have slits, goats have sort of rectangles, hippos have T shaped pupils... I know that hippos have eyes like that so it works like a periscope when they're half under water. What are some other types of pupils (imagined as well!) that have a reason for their shape?

Cat eyes have slits so they can open very very wide, which gives them excellent night vision, but can also close quite small so they don't damage their sensitive eyes in bright light. I dunno about goats, and that's pretty cool about hippos (I hadn't known that either). One of the characters in the Dragonlance series has hourglass-shaped pupils, but they don't mention them altering his vision. I wonder if perhaps they would make his peripheral vision in the vertical (above and below) better than the horizontal (left and right).

[Aimless]

Why would they need to block UV radiation? Why not see in UV? :o

I think you should make eyes secondary sexual organs alternatively one of the primary tools for communication, so that he accidentally finds himself trying to communicate with his eyes or staring at eyes a lot or whatever :o And then when some nice lady says he has nice eyes, he can faint :o

Oh yeah, obviously he can roll his eyes REALLY well ;)

EDIT: Yeah, let him see all the way into the UV spectrum. He should be able to spot all sorts of cool things that way :)

[Aimless]

Erm. So, not just his eyes but how they fit into everything else. If it's a very visual species then maybe angling his body in such a way that he doesn't usually look at you is a sign of trust? Stuff like that.

[snooze]

Cats don't scare me, but to have a goat stare you down is one of the freakiest experiences of your life.
There are the heart-shaped pupils of a notorious breed of valley girl, who buys messed up contacts for halloween...
Honestly, I think they would scare me more than any alien.

[Tundra]

I'll add social things about him as well of course, but right now i'm just working on appearance.