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Post by Robert Nordsieck on Jul 5, 2009 20:44:49 GMT
Hi @ll, I wrote a page with pictures of a blind snail, which my friend Mica found in Berlin. Kind regards Robert
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coyote
Archachatina papyracea
Cochleas ego amo
Posts: 2,955
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Post by coyote on Jul 6, 2009 4:50:11 GMT
Wow, I never thought about a snail being blind before. And while I knew snail eyes had lenses, I didn't know they lacked muscles for focusing their vision. I guess they don't see better than we think they can after all. But I'm not surprised a blind snail can get around fairly well in spite of it. Thanks for the pics and article!
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Post by Robert Nordsieck on Jul 6, 2009 10:30:58 GMT
Hi, neither did I, though I assumed that a snail will, of course, be blind, if the tentacle gets ripped off, like in amber snails, when they are infected with that worm, Leucochloridium paradoxum. What I also found out is, that octopuses, for example, do have lenticular muscles, but, in contrary to vertebrates, they do not use them to deform the lens, but to move it forward and back to focus the picture. Kind regards Robert
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zakalwe
Achatina achatina
Baby Amber Snails YAAAAAAAAAAAYYY!!!!
Posts: 43
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Post by zakalwe on Jul 6, 2009 19:09:22 GMT
Snails actually use their eyes more for setting and maintaining circadian rhythms than anything else. There is oddly enough, some pattern recognition in some species of pulmonates that helps them find certain plants and what not in their environment, but mostly it's just for confirming whether it's day or not.
Snails are cool.
Did you know they also have an organ for sensing their orientation to the earth's gravity well, as well as (potentially) and organ for sensing their magnetic orientation? coooooool.
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Post by Robert Nordsieck on Jul 6, 2009 22:14:21 GMT
I understand that snails have an equilibrium organ called the statocyste. Is that what you mean by "sensing their orientation to the earth's gravity well"?
What kind of organ is supposed to sense the earth's magnetic field, and which snails have it?
There are experiments to proove that snails can observe light and dark to leave their place of hiding, for example. As they also can differentiate between different forms, I think it to be exaggerated to say that snails use their eyes only to determine, what the day length is.
However, the blind snail prooves, that loss of the eyes does not hamper the snail too much, as it possesses several other senses suitable to its needs.
Regards Robert
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zakalwe
Achatina achatina
Baby Amber Snails YAAAAAAAAAAAYYY!!!!
Posts: 43
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Post by zakalwe on Jul 7, 2009 20:15:10 GMT
They're hypothesized to have a ferro-magnetic crystal to essentially give them a compass. I think it's mainly in sea slugs, though I believe there supposed to be several snails that have this ability as well. And you're right about the statcyste, I'd forgotten the name of it. As to the eyes, I didn't mean that they only use their eyes to regulate circadian rhythyms, merely that that was one of the main uses for them. Mostly snails use olfactory nerves in their eye stalks to find odors on wind currents, and chemoreceptors on their lower tentacles to "taste" the ground. Like I said before, snails are coooooooool.
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Post by Robert Nordsieck on Jul 8, 2009 10:34:30 GMT
Hi there,
could you recommend any literature where I could inform myself on the snails' compass?
Kind regards Robert
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zakalwe
Achatina achatina
Baby Amber Snails YAAAAAAAAAAAYYY!!!!
Posts: 43
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Post by zakalwe on Jul 8, 2009 15:32:12 GMT
I'm not really sure if there is any that's readily available. I was reading this book www.amazon.com/Behavior-Neural-Control-Gastropod-Molluscs/dp/0195113144and it was mentioning that tests were being done, but they didn't have any clear idea of what the snails were using to determine their magnetic orientation, or if they even were. I'll be borrowing the book again in another month or so to make notes, I'll PM you the bibliographic information when I do.
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snailgirl
Achatina achatina
Speedy And Captain Mollusk Loves You!
Posts: 56
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Post by snailgirl on Feb 2, 2010 23:10:49 GMT
i dont understand? that cutie looks like a regular snail? are they supposed to have a black spot or something?
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Post by Bumblebee on Feb 3, 2010 7:40:23 GMT
If you take a really close look on a snail, you should see a tiny black spot on the top of each of the eyestalks, witch is their pupil, but the snail in the link, it dosnt have any of those
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Post by crossless on Feb 3, 2010 14:20:21 GMT
My one snail has just one eye have had year all ready. Still she happy and slimes around. Her eye just shrink away, grow back with out eye, that's really freaky to hear but it's still really nice snail.
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coyote
Archachatina papyracea
Cochleas ego amo
Posts: 2,955
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Post by coyote on Feb 3, 2010 22:46:03 GMT
Snails don't seem to rely on their eyesight for survival as much as their other senses, so a defect of vision will not make as big a difference to them as it would to other species.
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