| T O P I C R E V I E W |
| BlueDragon |
Posted - 31/07/2011 : 10:48:11
I've always wondered just why it is that snakes have evolved to have no eye lids. I know they have eye caps, so their eyes are protected in a way, but all other reptiles have eye lids, so why not snakes? For an animal that is often found sliding through grass or up trees and strikes at their prey it seems a bit daft not to have them as protection against grass cuts, branches and teeth... well, it does to me anyway. What reason would their be to evolve them out? Does it have something to do with having no legs? I suppose they might find it hard to rub sleep out of their eyes in the morning! |
| 16 L A T E S T R E P L I E S (Newest First) |
| BlueDragon |
Posted - 02/08/2011 : 10:56:18
I watched Life In Cold Blood, but I can't remember them all now, it was a while ago.
I agree, I wouldn't be betting any money on many other animals to be able to carry on like Snakes can. The seem pretty unbeatable! But so do Crocs and Sharks. And Cockroaches! But could they cope blind? Well... maybe Cockroaches could.
I suppose we'd have to go back to when snakes first evolved, then, to find out why they have this eye scale thing going on and not a second eye lid or just eye lids. But, I don't know if anyone else knows better than me, but I don't know what exactly snakes evolved from : / Lizards, yes, but which one? |
| n/a |
Posted - 01/08/2011 : 17:20:10
Ah, I didn't see it myself till a year ago when someone posted it up on the darkside (I don't have TV at all.)
Yes, snakes are truly wondrous - I have known of disabled cats who have adapted to hunt, but I reckon snakes outdo everything. |
| jhk2005 |
Posted - 01/08/2011 : 17:04:54
Would you believe that i've never seen it?!   when it was being shown n tv I was working nights so I always missed it  (didn't have sky/sky+ see) but its me birthday soon and the dvd set is on my list of prezzies, hehe!
It's sad for all those poor snakes but it proves one thing - snakes are one of the most perfect creatures out there, right? how many other animals could hunt successfully (and independantly) if they lost their sight through injury/ill health?  |
| n/a |
Posted - 01/08/2011 : 15:39:04
Hi, jhk, did you ever see the David Attenborough series 'life in cold blood' - there are 6 episodes on snakes, on youtube.
There's an island where the snakes prey on fledgling seabirds ...and scarcely a snake on this island has two intact eyes - some are completely blinded because the birds defend their young by pecking at the snakes' eyes (I know - horrible!) Attenborough seems to show this to demonstrate how powerful the snakes' sense of smell is, as they go on hunting and killing even when totally blinded. (Which is reassuring, if hard cheese for the seabirds.)
I have a snake who was born with only one eye (Cy) and it's taken her a year, I would say, to adapt. Now she behaves like a normal two-eyed snake. |
| jhk2005 |
Posted - 01/08/2011 : 15:03:18
quote:
why have other hunters not evolved this supposedly very usful adaptation? Why not Crocodiles, for instance? They have a second eyelid, I suppose, but is that as good as protecting the eye as brille is? On documentaries you do tend to see a few Crocs with eyes missing or hurt so bad as to make the Croc blind in said eye, so would it not be a good idea for nature to give them the same adaptation as snakes? I suppose I'm asking why snakes and not other hunters? Especially other reptile hunters.
I've had a good look through most of my books and googled it too, the general theme seems to be the brille is a clear scale formed from the fusion of both eyelids ; admittedly now I looked more deeply into it, this is where the differences of opinion occur... The most common is protection from dust, dirt, superficial scratches etc and ranges up to protection from injury whilst hunting ; so in all honesty it now seems nobody really knows for sure...
I can't say i've ever seen a snake blind through injury, but it must be possible, when you consider some of the prey they tackle in the wild...
Going back to your point abut crocs, my guess is that nature ook a different path and gave them 2 eyelids for protection, but like everything else it's not a 100% guarantee ; whats also interesting is that according to wikipedia, "snakes, flap-footed lizards night lizards, and some skinks and geckos" have this adaptation so my money is definitley on protection but now i'm thinking less from prey and more general day-to-day protection.
btw, I only found out today 'brille' is the german word for glasses! gotta love wikipedia! I can just imagine all my little ones with big, bottle-top lenses looking like olive from 'on the buses'  |
| BlueDragon |
Posted - 01/08/2011 : 10:22:26
Yeah, actually I know that not all reptiles have eyelids... dunno why I said that : / I know some species of Gecko don't. But I don't think they have eye scales like snakes do... that's why they need to clean them with their tounge!
So I get that it makes them better hunters, or so we should beleive (they have been around or quite a long time!), so why have other hunters not evolved this supposedly very usful adaptation? Why not Crocodiles, for instance? They have a second eyelid, I suppose, but is that as good as protecting the eye as brille is? On documentaries you do tend to see a few Crocs with eyes missing or hurt so bad as to make the Croc blind in said eye, so would it not be a good idea for nature to give them the same adaptation as snakes? I suppose I'm asking why snakes and not other hunters? Especially other reptile hunters.
Do fish actually have eye scales? I didn't think they did. Although I can imagine that eye scales came before eye lids did. Makes sense.
BATS, I did used to witness Pandora wiping her mouth on her branch after feeding! Like Birds do. I don't know why she felt the need to do that (she wasn't covered in blood or anything), but I've never known of another Snake do it! |
| jonoandapril |
Posted - 01/08/2011 : 08:04:30
i have tried to stare out my royal... it is a mish cause even when she turns away, shes still staring straight at me. flippin evolution... |
| Lotabob |
Posted - 01/08/2011 : 01:13:12
I don't think eyelids evolved into eyescales, the other way maybe, going back to fish. My money is on eyescales been around long before eyelids.
THE BLACK EYED BOAS
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| Laws |
Posted - 31/07/2011 : 23:53:20
lotabob i havent seen them roll their eyes back , lexi is just so fast and strong , however it looks really scary with such black eyes! sharks do the same thing when they smell blood! |
| n/a |
Posted - 31/07/2011 : 20:02:36
Thanks jhk - it was total conjecture on my part though - with a little help from observing my snakes. |
| jhk2005 |
Posted - 31/07/2011 : 19:38:49
you're right on there Bats, a totally brille-iant reply! One possible reason is that nature evolved the lids into the clear scale known as the brille so that a snake had more protection for its eye (when hunting/escaping etc) than a basic eyelid without compromising its sight. I also remember seeing on a documentary years ago that another reason is that because most snakes are ambush predators the clear eye scale allowa them to go from sleeping to striking in a split second. :) |
| Lotabob |
Posted - 31/07/2011 : 18:44:25
Thats is their pupils opening taking in a LOT of visual information. Sanke does it too, she looks possessed, she also rolls them back when she strikes, looks a bit special. |
| Laws |
Posted - 31/07/2011 : 13:46:08
this is eye related , have any of u boas owners noticed ur boas eyes go completely black when feeding ? both dexter and lexi's did last nite it was weird! |
| SaltyTurtle |
Posted - 31/07/2011 : 13:26:23
I think it's so they can always win 'stare-out' contests. You will ALWAYS blink before snakey! |
| Lotabob |
Posted - 31/07/2011 : 12:17:26
Snakes aren't the only animal without eyelids, in fact not the only reptile without eyelids.
I think its we all evolved from fish/fishlike creatures and they dont have eyelids, so what they have worked well enough to not require any further evolution. Evolution isn't always whats best but more what works first. Though our human eyes are at far greater risk as the soft delicate bits are exposed and we have to rely on a reflex action to close it over but we are then disadvantaged as we cant see while protecting our eyes. Snakes can see 100% of the time and have the eye protected as well. For sleep purposes they just go somewhere dark, they also have the ability to close the pupil blocking out all but a dot of light (sometimes a few dots running the length of the vertical pupil). |
| n/a |
Posted - 31/07/2011 : 11:35:19
LOL! yes, you might have a point there - eyelids would provide folds of skin that the animal couldn't clean without limbs, so nature evolves the lids into - isn't it called the brille? The eyecap. Also the snake is super-alert without blinking lol eyelids, which can often give it the edge on escaping a predator or securing a meal.
Yeah, they'd go mad if they couldn't clean a part of themselves - have you watched them wiping their faces after drinking or a feed? |
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