What animal normally develops with only one eye?
Actually, I just heard of that Polyphemus moth, that's why I mentioned caterpillars. But I guess I was wrong on that one...Originally posted by Loren Booda
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.
Yes they have an eye spot but it is an organell and euglena are unicellular organism. It allow the cell to go toward or away from the ligth. The spot actually detect where the minimun ligth is coming from.Originally posted by Loren Booda
Don't euglena (the most primitive example of eyes I could think of) have an eye spot(s)?
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 seperate evolutionary development?Are two eyes more an outcome of symmetry or redundancy needs?
For the jelly fish it is still is symmetry. The jelly fish as a radial symmetry and has an eye for each plane, more or less.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 seperate evolutionary development?
That's the point, AG. If the "evolutionary accident" of having two eyes proved infinitely superior to having just one, then it could be considered a "minimum requirement" for surviving species, that they have two eyes (or none, like some species of fleas that live in wells).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.
Well, I was making a joke, since "Polyphemus moth" sounded like some rare breed that nobody usually hears about...so, I say "of course I've heard of that" .Originally posted by Loren Booda
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!
That makes me wonder though...some insects have "complex eyes", don't they? Wouldn't one such complex eye be sufficient, without the other?Originally posted by iansmith
Also what is interresting in anthropods, arachnids have multple eyes whereas insects and crusteceans have 2 eye.
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.