# Simple eyes



## Mantibama (Jan 15, 2010)

I recently finished reading through Prete's chapter on prey recognition and the chapter on vision and hearing (haven't finished the book, so if there is an explanation later forgive me) and it discussed binocular disparity in the fovea eliciting strikes and side-to-side peering for distance estimation all in regards to the compound eyes. I was wondering if anyone was aware of any theories for simple eye purpose in Mantodea. Are there any articles that could explain it? Thanks.


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## Rick (Jan 15, 2010)

I believe their purpose is to sense levels of light. I thought it was in the book.


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## ABbuggin (Jan 15, 2010)

Rick said:


> I believe their purpose is to sense levels of light.


That is correct.  Along with mantids, wasps and dragonflies have them too. (I'm sure others also)


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## Mantibama (Jan 15, 2010)

Doh, if it was in the book, I guess I missed it. Not surprising though, as I think the vision section was the hardest chapter for me to read and I could see myself just reading something without absorbing what it said. That book is really intensive and I find myself rereading paragraphs. So, simple eyes sense light. I wonder what kind of behavioral effects being able to determine light levels brings about. Maybe knowing light levels allows mantids to recognize prey with relative contrast between day and night. Thanks for the answer though.


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## ABbuggin (Jan 15, 2010)

I agree with you, it is a very intensive book. I can only read but so much of it at a time. :wacko:


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## PhilinYuma (Jan 16, 2010)

Well, you didn't miss much excitement, Bryce. Research on insect ocelli, mostly in the mantids' cousins, the grasshoppers, was being done back in the thirties. Almosy every article or abstract that I have read, though ends up by stating what new has been discovered. !Even Christian has admitted to being stumped as to their function!

Modern sources suggest that they might serve at least two functions: as a means of distinguishing a change in photoperid and as a means of recognizing the horizon during flight. Neither of these is more than a hypothesis, so far as I know, but both may have very important consequences for mantises (or mantids or mantes!  ).

1) The ability to detect photoperiod may be redundant. In a discussion of diapause, Gullan and Cranston confidently state that photoperiod is detected directly by brain photoreceptors and not by the compound eyes and ocelli (p.158), but this relies on an unsupported assumption that all diapausing insects use the same sensors

2) I have wondered why, if the ocelli are used as a device for horizon detection, they are present in mantis (and dragonfly) nymphs and in essentially flightless females. Although the Prete book doesn't adress this issue specifically, it does show (though this is not a new discovery), that the adult's ocelli are better developed than those of nymphs and that the males have larger ones than the females, which is consistent with the horizon finding hypothesis.

I don't know whether this helps or adds to the confusion!


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## Mantibama (Jan 16, 2010)

Ah, I actually vaguely remember reading the part on ocelli development now. Sounds like this question will ultimately have to be filed in the ask later department of my brain, but I appreciate everyone bringing me up-to-date on information available so far.


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## kamakiri (Jan 17, 2010)

Just because a female may not need them...it does not mean she shouldn't have them to pass on to her male offspring, no?


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## PhilinYuma (Jan 17, 2010)

kamakiri said:


> Just because a female may not need them...it does not mean she shouldn't have them to pass on to her male offspring, no?


A female can transmit the genes for a given trait without their being expressed, though, the trait may be expressed in an underdeveloped or vestigial form. The latter can happen with both primary and secondary sexual characteristics, such as male nipples or the female clitoris in mammals, while the former strategy is demonstrated in testes and ovary. Horns are secondary male sex organs, but in some genera of ungulates, such as the bighorn sheep, the females possess undeveloped horns while in others, such as water bucks the female is without horns.In theological circles, this is known as "God keeping his options open."


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