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Loren Booda
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What animal normally develops with only one eye?
Originally posted by Loren Booda
What animal normally develops with only one eye?
Originally posted by Loren Booda
Mentat,
have you heard of the Polyphemus moth? Named after the Cyclops that Ulysses killed. It has at least two real eyes, though, as do all caterpillars to my knowledge.
Originally posted by Loren Booda
Don't euglena (the most primitive example of eyes I could think of) have an eye spot(s)?
I cast my vote for Symmetry.Originally posted by Loren Booda
Another God et al.,
Are two eyes more an outcome of symmetry or redundancy needs?
Hmm... but it seems that multi-eyes were more common with the more primative creatures of the sea, eg. jellyfish etc. At what point did they go back down to two eyes, or were the two-eyed creatures the result of a separate evolutionary development?Are two eyes more an outcome of symmetry or redundancy needs?
Originally posted by FZ+
Hmm... but it seems that multi-eyes were more common with the more primative creatures of the sea, eg. jellyfish etc. At what point did they go back down to two eyes, or were the two-eyed creatures the result of a separate evolutionary development?
Originally posted by Another God
I'm not a fan of this "Minimum 2 required' phrase...it makes it sound like things can't live without two eyes...
There is an undoubted evolutionary advantage in having 2 eyes over one, and since we are symetrical it makes sense that everything should have 2 eyes... But I am ready to accept that it was just another evolutionary accident frozen in time on account of its practicality.
Originally posted by Loren Booda
Mentat,
I'm jest-asking. The Polyphemus moth has a prominant "eye spot" as protective coloration on each wing. Birds spear the spot, not the moth!
Originally posted by iansmith
Also what is interresting in anthropods, arachnids have multple eyes whereas insects and crusteceans have 2 eye.
Originally posted by Loren Booda
Are two eyes more an outcome of symmetry or redundancy needs?
Interesting, and I think it might have been nice to have had a single ear where my mouth currently is while having two mouths where my ears are. I could drink and chew a banana all at the same time.True: most all animals are symmetrical, but that doesn't mean that you must have 2 of something. Mamals generally only have one tongue, penis/vagina, tail etc. so humans could be just as symmetrical with only one eye.
How very true!Originally posted by Loren Booda
There once was a man from Nantucket...
... who had... a bucket??Originally posted by Loren Booda
There once was a man from Nantucket...
Originally posted by Njorl
I think "the man from Nantucket" would be genetically selected against. I mean, why ever go out?
There are asymmetries. There are singular internal organs that are not in the center, liver, stomach, appendix etc.
I bet external asymmetries might have been selected against. Consider the case where some are natural. An additional asymmetry would be a genetic defect, which would usually be harmful. It would be more rare for a symmetry to be the result of a harmful (or any) defect. So, when choosing a prospective mate, choosing the more symmetric one would have a better chance of producing thriving offspring.
Unless you're a fiddler crab.
Njorl
The condition is called Situs Inversus and in principle doesn't bring any complications with it.Originally posted by Loren Booda
Then there's the asymmetry in some unfortunate humans where almost all of the internal organs and/or systems are reversed. Does anyone know the name of this condition, and what its complications are?