Let's see, we got round, elliptic, triangular, hearts-haped, and many more shapes of pupills in our world. We have eyes whit a cammuflating irises and we have tiny and huge eyes.
Have you ever wondered why or what pupillas would be more suitable for your creature?
Or perhaps if it should have huge eyes?
Or why sudden bright light is painfull at first and blinds us for a short instance?
Its acctually a link, not sure if it even belongs here. It's not so amazingly well written, and the images have crap quality, but I found it extremely useful anyway :)
[Animal Eyes (http://www.schools.net.au/edu/lesson_ideas/optics/optics_wksht1_p1.html)]
[Bioluminence (http://www.schools.net.au/edu/lesson_ideas/optics/optics_wksht5_p1.html)] (how deepsea fish see, considering there is nearly no light there)
Another site on Bioluminence (http://www.lifesci.ucsb.edu/%7Ebiolum/)
Edit:Oooh~ found a more usefull link on bioluminence :)!