Life is fascinating. Our lives? Sure, but that's not quite what I mean.
While snake's eyes don't look too much different from lizard's eyes, they function quite differently. For one thing, they don't have lids, where lizards have three. Their eyes are protected instead by a transparent lens. There are other differences as well, including the way the eyes focus.
And needless to say these eyes are different from just about any other land vertebrate. Why is that? Well, one should be humble when discussing evolution, since we don't see it and information is always changing. But it seems like when they split from lizards they moved largely underground and were nocturnal. Their eyes atrophied from lack of use. Then when conditions changed they re-evolved their visual systems, fulfilling many of the same purposes in different ways.
Absolutely filled with surprises.
2 comments:
Nice snakey title up there.
I delight in how fascinating are the things you wonder about. You're right that snakes without eyelids who are able to see is a very intriguing mystery - one I'd never considered, never mind that they're an incredibly old species when compared to mammals. That the ancestors of snakes are lizards who went underground makes sense, but the other theory I read about on wiki is that they're descended from aquatic reptiles and their fused eyelids evolved to combat corneal water loss through osmosis. The real answer is one we're unlikely to learn.
Of course the other thing that's always interesting is what do other creatures see. We can be pretty sure that all people see things as we do but what about birds or creatures with compound eyes. It's hard to think outside of one's own experience.
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The video of the Finnish figure skater who can't skate.
I copied and pasted it from somewhere I don't remember. It is fun.
Yes, snakes arose during the time of the dinosaurs, so they likely would have been well established when the first mammals came on the scene. Their body setup is odd among vertebrates, but it seems to work for them. The aquatic theory is new to me. It's also interesting. There certainly is no shortage of aquatic reptiles that could have connection to land life.
I've been thinking about different kinds of vision. The compound eye vision of creatures like insects is very different from the kind of stereoscopic in-depth vision we have. It evolved for different purposes, really. Birds do have eyes more like ours but they also tend to be tetrachromats, meaning that they see four primary colors as compared to our three. It's hard to imagine what this is like on a regular basis. I can sort of wrap my head around the idea of trichromats who see ultraviolet instead of red.
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The Finnish figure skater is, well...He's getting attention. So many people have forgotten that's not the only thing.
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