Stupid fly and intelligent bee
If one of your eyes were covered and you were asked to approach the door from a distance of a few metres, you would experience no difficulty whatsoever and walk straight up to it. If you were a crab, a beetle or a fly it would be a different story.
Unilateral blinding in these and related animals leads to a behaviour known as “circus movements”. Deprived of vision in one eye, the central nervous system of these animals reacts to the imbalance of the photic input in the following way: a signal travels from the eyes to the brain and informs it from which side the brightest light arrives. From the brain a command then reaches the legs and tells them “Move to where the light comes from!” (or “move away from the dark!”).
In other words, if the right eye of a fly were painted black, the fly would move to the left in search of the light source it receives on that side of the body: consequently the fly wouldn’t run (or fly) any longer in a straight line, but would now perform anti-clockwise circles, whose diameters would depend on the surrounding light level (brighter lights leading to smaller circles). The head of the fly would be held somewhat obliquely with the uncovered eye positioned higher than that on the opposite side.
However, if after an hour or so the paint was to be pealed off the right eye, the fly would then undergo some clockwise circus movements – not as a rebound effect or to unwind, but because the covered right eye had become so sensitive to light during the while it had been in the dark that now it and not the other (seeing) eye would be sending the message of the direction of the brightest stimulus to the brain. If the lower halves of a fly’s eye were painted black, the insect would lift its head as high as it possibly could and might even summersault backward, but if the dorsal halves were painted, it would lower its head and bend its forelegs down.
Unilaterally blinded flies and most other bugs, behave in an inflexible, “stupid” way and do not appear to be able to learn to crawl or fly in a straight line again, even if given ample of time to exercise and practice. Honey bees, the geniuses of the insect world, on the other hand, master this little intelligence test for insects with flying colours: a few circus movements is all they need before going straight again, even if one eye remains covered. The method outlined to determine an insect’s IQ is simple and may even be more reliable that that used to find the human equivalent. But whichever you may look at this, going in circles sure ain’t take you anywhere.“[/caption]
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2016.
Unauthorized use and/or duplication of this material without express and written permission from this site’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to V.B Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com with appropriate and specific direction to the original content.