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Alithographica — Science Fact Friday: Nictitating Membranes
#anatomy #animation #biology #bird #eye #eyelid #falcon #gif #illustration #nature #physiology #science #scientific #scientificillustration #scopophobia #wildlife
Published: 2018-06-29 19:25:41 +0000 UTC; Views: 2468; Favourites: 94; Downloads: 23
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If I could release a patch for human anatomy, it’d include the restoration of a full nictitating membrane. It keeps a falcon’s eyeball from drying out during fast flight, protects vulture’s eyes from all the gore they push into while eating, creates a diving goggle for polar bears and amphibians...We lost our nictitating membrane because we didn’t really need it anymore but I want it back.
(Cats and dogs have nictitating membranes too but they’re usually kept retracted. You may see them if the animal has its eyes open slightly during sleep, though.)
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Comments: 10
Do horses have this membrane, too? I think there is such a pink spot at their eye corner, too.
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Well, after dealing with dogs and occasional cats with prolapsed lacrimal gland of the 3rd eyelid (so-called cherry eye) which has to be surgically corrected most of the time (or removed completely if someone still practices 18th century medicine, duh)... I, for once, definitely would not want to have this piece of anatomy back!
Yay for the gif! And I love how simply you could you achieve that slight translucency!
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Thanks! I am generally not super squeamish but cherry eye is one of the things that makes me cringe lmao
I've heard of it happening a lot in dogs and humans, a bit less so in cats, but it seemingly happens less in birds and other animals with fuller use of the membrane. I don't really know why this is though?? Not finding any helpful answers anywhere. ;v
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According to Slatter's vet ophthalmology textbook, cherry eye likely results from a combination of lymphoid hyperplasia and laxity of the retinaculum that attaches 3rd eyelid to the periorbita... Follicular hyperplasia is basically an overt reaction to novel antigens in young animals, and the retinacular laxity seems to be genetically predisposed (brachycephalic animals in particular). Given that both allergic diseases and brachycephalic traits are all too common in dogs, no wonder they get cherry eye more often as a result! I have no idea about humans, but expect something similar. Also, 3rd eyelid can protrude due to other causes including neoplasia, Horner's syndrome and plain old pain (cats and dogs both have retractor bulbi muscle- eye gets pulled inwards in response to pain, 3rd eyelid "pops out". Humans don't have that muscle, which I find kind of cool.) Yay for the nerdity!
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Huh! This is super cool, thanks for the extra info.
Lol brachycephaly. I can't even keep track of all the issues that are caused by or comorbid with it, doesn't surprise me that cherry eye is one of those.
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No problem, I'm very glad to find bio interested people in here! Well, yea, brachycephalics. Nothing says "cute" more than needing an operation, (or, more often, two) just to be able to breathe! :/
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[[breathing intensifies]]
[[rigorous snorting and huffing and constant reminders that we did this intentionally]]
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