I am happy you looked up the article. UV vision is one of the interesting features of insect physiology. It also demonstrates how expanding sensory perception allows for unexpected perspectives on the world. Birds and some insects can "see" the earth's magnetic field and use it for migration, and I cannot imagine what that must look like. Insects can also "see" polarized light and social insects use it for orientation with their nest or food sources. More factlets :-).
Thanks for the video! Needed to learn this for a species in a comic i'm developing! This is the most informative video I found for compound eyes on youtube. Thanks again! :)
Its much more fascinating when its well-explained. You have superb animations as well; they're logical and provide good intuition into how the concept works. Your videos are highly under-viewed. Thank you for sharing your knowledge.
Thank you Tom for the nice comments. I am happy that you found the videos of interest and edifying. For some reason the idea that insects see the world as multiple single images got promoted to the public and caught on in some sci-fi movies and comics, but it is a fallacy.
i always thought: What benefit would 1000's of the same image server the creature? surely they must process and stitch the image together, or use the light gathered to form a sense of direction and distance
Small nitpick. At 0:38 it should be noted that each facet only accounts for a single pixel or two in an insect's vision (because of this, they are known for having really low resolution vision), so you're representation of what they see is also technically wrong. But it's obvious what you were going for.
Thanks for making this video. I've tried a number of books and websites for an understanding of insect vision and all of them were confusing. Your presentation being the clearest was the best explanation of them all and extremely helpful. Much appreciated.
Thank you so, so much for this video! I am taking an entomology class and have read the vision section of my textbook and numerous papers and websites and really couldn't get exactly how the different eyes worked until I watched this video. Then I watched it over and over to be sure I fully understood it. Very much appreciated!
+twistedyogert No, they have color vision. They can see into the UV (300-400 nm) but not well in the yelloq-red spectrum. There are some excellent pictures on Widipedia and videos on RUclips of the world in the UV range. Flowers in particular take advantage of insect vision in the UV by using UV-reflective stirpes (pollen guides) to attract pollinators to the center of the flower region containing pollen.
I have two questions: Several years ago I was working the night shift as an arc welder. One night I finished a long weld and lifted my welding hood to notice a large dragonfly sitting on my table. I like dragonflies and brushed my hand to scare it away but it didn't respond. It was alive because I could see it thorax going in and out as it "breathed" I finally picked it up and threw it into the air. It tried to fly but it seemed to have no control. It tumbled this way and that and finally hit the ground. I've wondered if maybe it didn't go blind as a result of the arc light. If id did go blind would it's vision be lost permanently or would it come back like a human's eye adjusts to a dark room after coming in on a bright sunny day? My other question is generated by this same job. Insects flying into my weld zone was a real problem. The insect would be burned up instantly and its body would be incorporated into the weld. This would mean stopping, grinding out the weld and re-welding. Why would the insects be so strongly attracted to such an intence light sourse. especially ultraviolet, a wavelength they would rarely see? Adding to this, why would insects be attracted to bright light anyway? The sun is the brightest light in the natural world in the day time, but insects don't try to fly into it. If they did they would climb as high as they could and eventually freeze or die from asphyxia. At night the moon would present the same problem. In addition forest fires have been burning for as long as there have been forests. Why haven't insects developed an aversion to fire? Fires produce a lot of infrared light which can be seen as light. Why would an insect fly into something so hot it dies instantly?
I can answer some of your questions, but not all. I cannot say why the dragonfly was disoriented. Possibly it had been blinded by the intense light and I really cannot say if it would be permanent or temporary. Possibly it got near the heat, as well. As to why insects fly toward your welding which emits UV, in fact, insects are acutely sensitive to UV. They see very well in the 300-400 nm range, which we do not. They are very sensitive to UV, but not to red. Insects do not see into the red spectrum. Blue flowers are insect pollinated; red flowers are pollinated by vertebrate animals (bats, birds). That would explain why they are attracted and fly into your welding - strong UV emission. We (entomologists) actually use "black" lights to attract insects at night for collecting and sampling purposes. Flowers have UV reflecting lines, which we cannot see called honey guides, that point insects to the pollen and nectar in the flower center. There are some websites that show how different the world looks to an insect in the UV range if you google insect vision and UV. You ask about the sun and moon. Black-light trap catches are decreased on full moon nights. Apparently, nocturnal insects are less active on moonlit nights or the moonlight offsets the attractiveness of the black light by being a more attractive focal point and distraction to the black light. Or, possibly they are less active because they are better prey for predators on moonlight nights? As to why they don't fly toward the sun, I cannot say for sure, but in the daytime there is ample light all around, and the sun is not the focal point for the light, like the moon or a porch light are, at night.
@@llkeeley I think that the Dragonfly would have been permanently damaged by the UV light, our eyes have the ability to control the amount of light hitting our retina by adjusting the size of the pupil and plus we have eyelids. The compound eye doesn't have eyelids or the ability to control the amount of light hitting the retinal cells.
@@twistedyogert Insects actually perceive UV wavelengths and "see" things in that region of the spectrum (unlike vertbrates). They do not have eyelids and contractile pupils, but they have expandable shielding pigments that surround the retinula cells and block excessive light (watch all the scenes as these are explained under eye structure and in the scene on diurnal and nocturnal eyes). So I am not sure I agree with the idea of damage to the retinuila cells. I won't discount it but they withstand a lot of light in the daytime with no damage. If the welder was working at night as indicated, dragonflies are diurnal insects and it may have been in a quiescent "sleep" state called torpor. Diurnal insects often hide at night and are quiescent and difficult to arouse, then become active again in the day.
Thank you very much for this vid - I had to rewind a few times and readhear certain nomenclature, but I appreciate the level of articulation this video achieves. Great job!
Wow, this is informative and amazing. The insect eye is basically a digital camera. There are lenses, pixels arranged into a sensor array, wiring for connecting to the brain (CPU) and insulation between the wiring.
I've actually read articles about creating artificial compound eyes for autonomous UAVs (drones), apparently the sensors mimicking the compound eye don't require as much processing power as an ordinary camera would.
Dear Dr. Larry, Thanks so much for creating this high quality, very informative, and detail video. It's pretty easy to understand and the diagrams are excellent. The insect compound eye is really amazing and exciting. I love the part where we get to see what the insect does! COOL! The complexity of nature is jaw dropping! Am I right in assuming the number of Ommatidia vary by species? If so, what species has the fewest? Well, thanks again for sharing this very cool stuff!
Reading a paper on the role of the sevenless gene in PTK signaling in Dmel and its influence on the development of the R7 cell. Your excellent video explains so well what the geneticists did not. Thank you!
Great clip! I've been geeking out on compound eyes for the past year, but this was just an awesome breakdown along with the visualizations! Thanks for sharing this!
Excellent! I'm preparing a short talk on Polarisation of Light (Physics) and I read that some insects can actually detect polarisation (and use it for orientation). This video is very helpful to understand insect's vision. Thanks!
This is called the pseudo-pupil. In large compound eyes there are flattened regions that have closely-packed and aligned ommatidia to enhance the detail of the view. As you go around the eye the black pupil appears to move with you, and these are the ommatidia that you are looking directly into. You are looking straight to the back of the eye and the light is being absorbed probably by both the visual and screening pigments.
You are correct, they have a merged image, like a mosaic. As shown the image of far objects are blurry because the eye focal length is for close objects and is not adjustable. Also the ommatidia surround the head so bees would see in nearly 360 deg. Insects see into the UV but not much in red wavelengths. Flowers petals have UV reflective lines called "nectar guides" that point to the heart of the flower and pollen. Bees also detect polarized light for navigation. Try googling these for more.
Not sure where you perceive there to be a blind spot? At ommatidial junctions? Between the primary sensory information at the cornea and the final "experience" of the view in the brain are 3 levels of synaptic integration that would permit perception of a single, unified image within the brain.
It would appear as a blend. Each ommatidium would be like a pixel. Since the lens is "near-sighted" it would be a blur of varying degree of brightness. The difference between adjacent ommatidia is what is relevant. The insect eye is most sensitive to movement not a detailed view. Obviously the more ommatidia, the more definition-like jpg vs bmp. E.g. mantids, dragonflies w/many ommatidia are acutely sensitive to moving prey. At the brain level it is probably an integrated, but blurry view
Fascinating, thank you for this excellent presentation! I thought that insect brains might make compensations similar to the human brain, and that the vision might not be perceived as mosaic. How is it known that this is how it's perceived?
This is something I’m existentially struggling with. Suggested video includes typical pop science countdown video of different animals and their perspectives. I can’t even click on it because I have no answer to your last question. I’ll need to read more literature. It really really pisses me off that these random assumptions about a biological phenomenon made by simply word of mouth and the media picks up whatever sounds coolest.
Yes, I am aware of that for the vertebrate eye. I think it is where the optic nerve emerges. For insects, each ommatidium is like its own eye. See the video on structure: each ommatidium has a lens, a cone to focus light on the receptors (rhabdoms=photoreceptive neurons) and their axons extend to the first synapse behind the eye where the optic nerve forms.Visual fields of adjoining ommatidia also overlap to some degree, based on lens size. I do not know of a similar "blind spot" for insects.
Thank you for the comment. I am happy that you found it useful and informative. You are correct in that different species have different numbers of ommatidia. Primitive species in orders like Collembola (springtails), Protura (coneheads), and Thysanura (silverfish) may have none and no more than 8; dragonflies: tens of thousands (30,000 is one number I found); fruitflies: 700-800. So it is quite variable. It depends on the size of the insect, and habits (active, flying; slow;crawling, etc.).
That's a good question, but no, I doubt there is cause-effect. Hexagons are the most efficient shape for maximum use of a surface area. So a hexagon shape to ommatidia and to honey cells is the best way to pack in the most visual units or honey in a given space, respectively. I think it is a quirk of evolution and chance that they are the same. As I indicated below the mosaic shape is probably only evident in the outer eye, and the brain integrates the view into a continuous image.
Hi Larry, this is what I got for the night vision, the explaination is slightly different from yours, can you kindly comment on it? Thanks! "In dark-adapted eyes (2 h after light off) the rhabdom becomes shorter and fatter, and the aperture around the rhabdom tip widens to 12 µm, which enlarges the rhabdom’s field of view to about 40◦, increasing sensitivity almost six-fold at the expense of resolution. In dark-adapted eyes (2 h after light off) the rhabdom becomes shorter and fatter, and the aperture around the rhabdom tip widens to 12 µm, which enlarges the rhabdom’s field of view to about 40◦, increasing sensitivity almost six-fold at the expense of resolution.
I was just about to ask the same question when I noticed your discussion. I observed the same phenomenon while photographing dragonflies. It's funny how our mammalian brains instinctively interpret this as intentional observation of a single target while the insect is literally just looking around.
Wonderful, thank you. Using the video to help me study for a third year paper at Massey (NZ), it really sheds some light on the concepts - pun intended!
I am doing an art projec where i try to record a day from the perspective of a honey bee. This was very helpful. I was afraid bees would see hundreds of images based on each omatidia, but if I understand you correctly they merge the information in their brain to create a single image that is only subdivided into honeycomb-shaped parts to detect contrast and movement. I wonder if you know how many omatidia a regular european honey bee has. I want to be as accurate as possible with depth of field.
On flowers, the streaks on the petals and the bulls-eye appearance leads to the honey and pollen in the center that is food for the insect and pollinates the plant. Also, butterfly species that are toxic to vertebrate predators often have bright warning spots on their wings. In males, these spots also reflect UV and flash" on and off like neon lights as they fly. This on-off flash is an attractant signal for females. So the spots both warn vertebrate predators, and signal insect females as mates
Very interesting material! Are the shielding pigment cells, of nocturnal insects, easily adjusted to fit the current surroundings or are they governed by an internal clock of sorts? I ask because I've got silverfish(which I presume are nocturnal, due to mostly nightly activity) living in my bathroom, and I wonder how turning on the lights at night impacts them.
Excellent question.We see from approx 400-650 nm wavelength (blue to red) insects see from approx. 300-550 nm) (UV to green-yellow). So they can see into the UV, which we cannot and they do not see the red very well, and we do, To see what insects see vs vertebrates, google "ultraviolet vision insects" and go to "the bee's eye view" in the UK Daily Mail, near the bottom. It has nice color pix of our view vs insect UV. It is a different worldview. So, yes, they see color well, just different.
This video covers 3 topics: structure, day-night adaptation, & mosaic vision. We know insects see like this by research from many labs, worldwide, on ommatidia ultrastructure, their optic properties, their electrophysiology and insect behavior.Mosaic vision is based on direct microscopic observation of light at the focal points for clusters of isolated corneal lens. Individual ommatidium views become integrated at the brain level by intervening chiasma with convergent synapse. Hope this helps.
There's a spot on your eye where the optic nerve connects, you can find the blind spot by covering one eye, and looking at a piece of blank paper with a colored dot on it. If you move your focus to a certain position, the dot will vanish, even though it should be near the center of your vision
Good video, gotta have a lot of patience for it and I doubt I could remember all the technical terms, but good illustration of insect sight. I'm wondering if you could create an insect eye as a large working model from this somehow, using some sort of clear plastic and a hemisphere with grids/slots for ommatidia? I wonder if anyone's built anything like that.
Interesting video. Thanks for sharing. Would a single ommatidium be capable of resolving the contrast between the sky and tree line/water, or would it appear as a blended mix of the two?
+Larry Keeley, the video was very instructive and useful for me. Thank you for making it public. Could you clarify a point? The illustrations depict each ommatidium having multi-pixel resolution. This might be consistent with each ommatidium having 7-8 retinula cells. If the crystalline cone has high transparency, the retinula cells could detect 7-8 pixels per ommatidium. If the photoreceptor molecules within each retinula cell align, say, along or perpendicular to the radius from the center of the ommatidium, this could explain the detection of polarization. If the crystalline cone is more translucent than transparent, the light hitting the retinula cells would be an average of what appears "out there" and the bundle would act as a single pixel. Consistent with that, one of your comments about two years ago stated that each ommatidium provides a single pixel to the brain. This demands the question, why 7-8 retinula cells? Why not four or even one? (I suppose the need to detect polarization would still require at least four; and it's probably a safe assumption that multiple retinula cells enable detection at multiple wavelengths.) Thanks for considering my question.
I imagine the number of pixels is determined by the number of rhabdoms per ommatidium. Since each ommatidium has only one rhabdom, I would infer than each ommatidium only provides one pixel of the compound image, not several. Regardless, the ommatidium would not provide the high resolution images he showed in the video.
sir i am doing msc in entomology in india ...my question in larval stage the insect looks like ugly ..but once its become adult it become beautiful like butterfly .what is the reason behind this.. and another question is do the insects have memory?????please clarify me sir...
Larvae are eating machines for growth. Hence, they want to stay localized and hidden near a supply of food, and be ugly so as not to be eaten themselves, while they feed and grow. Adults on the other hand are for reproduction and dissemination of the species. So they have adaptations of body structures used for mate finding (such as flying) and attraction (colors, cuticle ornamentation, pheromones, etc) and finally egg laying for females to disseminate the individuals and maximize environmental potential. As to memory, there is some evidence that some of the social insects might learn and actually "teach" others. However, most species' behavior is probably reflexive stimulus-response. There is little need for memory (and learning) if you do not live long.
Nearly all living organisms move away from noxious stimuli. Whether they have specialized nervous cells or are a single-celled organisms like a Protozoa. Pain is a subjective concept that we as humans (and all higher animals with developed nervous systems) recognize. The reason for pain is to warn the organism that they are in danger and need to pay attention as their survival could be threatened. Since insects have developed nervous systems, I would speculate that yes, they do feel discomfort and since in my experience, they do evade "danger" -- which might involve damage and pain. That said, I doubt that they contemplate it as a threat to their life, as we recognize when we feel serious pain. So I suspect they detect pain, but at a different level of consciousness. Many insects do not respond very dramatically to injury, so since it is so subjective, it is hard to know if it plays much role in insects. Much of insect behavior is based on a stimulus-response reflex, rather than contemplation. I do think they experience discomfort, whether they consider it pain--????
Why can't honeybees see the color red? They have trichromatic color vision like we do, and most people can see red, green, blue, and different combinations of those wavelengths, creating the full rainbow. Bees are capable of seeing green to UV wavelengths but not red.
Ocelli are quite different . They are a single lens with multiple photoreceptors and are thought to be sensitive to light-dark but not to form. They might play a role in maintaining stability in flight . Check out Wikipedia for a more detailed explanation.
Yes, what I am showing is what they perceive at the level of the retina - the back of the ommatidium There are several levels of synaptic integration before the visual receptor signal gets to the brain to fuse the view into a unified pattern. However, each ommatidium views the scene from its perspective in the eye and cutting across ommatidia (movement) is mainly what insects are most sensitive, not a detailed view. They see best broken patterns and edges that transect adjacent ommatidia.
These tiny lenses should have very large depth of field, so maybe it doesnt matter that they cant change focus... a large aperture lense like that in our eyes, needs to change focus, because the depth of field for a larger aperture lens is alot shallower.... So maybe the facetted eye sidesteps the need to focus all together...
I knew it couldn't be true that an insects sees multiple images of the same scene per eye! How would that sort of vision be of any use to the insect? That would be the next best thing to being blind. The only issue I have upon seeing this vid is, I doubt pretty seriously that insects have a grid pattern superimposed upon their field of vision. Don't you think their brains/nervous systems would resolve this into one clean image?
I know that arthopods in the ocean also have either superposition or apposition compound eyes, do the shielding pigments in other arthropod classes retract just the same? And what about deep sea arthropods where light doesn't change with the sun but only changes when bioluminescence is present? Or is the retraction (or absence) of the shielding pigments a permanent state?
Hi Larry, great video. What I always wondered, even more then to how/what they see, is how fast they must perceive the world small as they are. i.o.w. how slow they must see us move.. wouldn't that be interesting too? As their eyes are sensitive to motion, this speedfactor must influence the theory on how good they actually see big time i'd say. As they have more time to view things, because they perceive the world in slo-mo.. pity for them their 'direct' enemies do too.
What do you think of thie relationship between the haxagonal shape of the honeycomb in a bees nest and their eyes? I wonder if the ability of them to create the seeming perfect hexagonal pattern has anything to do with their eye structure.
It actually has to do with geometry. If you want to pack lots of polygons together on a plane the hexagon both interlocks with other hexagons so there’s no wasted space and it approximates a circle so it has the best area to perimeter ratio. Bees use it in hives because it gives them the most space inside a cell for the least amount of Bees wax wall and the cells interlock. Probably a similar reason for why omitidia are hexagonal
Contrary to this, I would expect that the sharpness of the image is independent of distance in the compound eye, albeit with magnification increasing as distance to the eye decreases. 10:20
When you depict "how an insect would see it", what is your basis for having the lines between what each "eye" in the compound eye sees? We have two eyes and rarely do we ever see a line distinguishing the field of vision between them... And that is two different eyes. Wouldn't it similarly be perceived without the "framing" by the insect within the same eye?
Sebastian You raise an excellent point and I think you are likely correct. Let me explain. Insect vision through the compound eye has been illustrated frequently in the "popular press" and movies that insects "see" a broken, scene because of the hexagonal facets that comprise the eye. And that each facet "sees" the same thing repeatedly, and that is not true. The insect sees a mosaic of a single scene. What I was trying to demonstrate is that each facet sees the visual scene based on its configuration in the eye and its field of vision and focus. The easy way to show this is to show each facet "looking" at its field of vision in the mosaic with the facet edges showing. Actually, what the insect "sees" is, probably, exactly what you suggest. Although each facet does have its own neurons that detect and transmit the light entering that facet, the neurons undergo synapses before they enter the visual centers of the brain so that the signals of each facet can become combined into an overall "scene" at the level of conscious comprehension by the brain. Therefore, like us, they see with each facet but integrate and fuse the overall scene into something more comprehensible when it is actually perceived at the conscious level that leads to behavior. Of course, I could be wrong and they do see the outlines of the facet -- just as you and I cannot know what each other "sees" when we look at something. Sense perception is unique to the perceiver and although we all think we see, smell, taste etc. alike; we also know that is not true. For example, we know that some individuals have color blindness or age-related sensitivity to different wavelengths of sound. We do know that insects are most sensitive to edges of objects and patterns and movement - things that cut across ommatidial fields of vision, but whether they actually perceive the boundary of their own ommatidia is unlikely -- as you point out. But, showing the boundary makes it easier to explain and understand in the tutorial. Thanks for the question as it is a good one and allows me to make the point about individual differences in sensory perception, i.e. perception is in the "eye" of the "beholder".
@@llkeeley Thanks you for your response. We're I to speculate, I would venture to say that the compound eye would likely be more sensitive to certain forms of movement (I don't want to assume all movement) for one two reasons. First, when something completely disrupts the sight in one of our eyes, it is impossible to ignore. In similar manner, an entire "facet" ("eye within an eye" if you will) would probably irritate or draw immediate attention from the insect. The second reason I hypothesize this is because it may be that so long as something does not move between the borders of the facets, the insect sees a single image much like we do with both our eyes. However, if something hits the sweet spot between where multiple facets see it, it might be like when something moves between our eyes (into just the right spot), causing us to have to immediately readjust and refocus. The object now had our undivided attention. This is purely creative speculation on my part but it would seem to make sense. I would be interested to hear your thoughts.
I agree. Anything in one facet appears static but when it moves to the other then it is "noticed" Since insects cannot roll their eyes it would have to move from one to the other facet to be perceived as moving.
@@llkeeley What's interesting is that this almost implies that thier visual acuity is roughly as detailed as the image of a yard viewed from a moving vehicle through the slats of a fence (if you have ever experienced this phenomenon). The colors are present but the "lines" are... Not "blurred" exactly but required far more strain to perceive.
Your presentation seems to suggest that insects see shapes within each facet of their eye. However, your explanation of the anatomy of the eye suggests that they see a single dot per facet. If I have this wrong, please explain.
I state right in the first scene that the single-facet repeated view of the entire scene is what "popular" concept, but that this is erroneous. What they really see is similar to what we see in that each facet sees a part of the view from its own perspective not repeated entire images in each facet. I saythat in the start of the first scene and describe it detail in the entire last scene.
I was just fooling around in a lazy afternoon when I asked myself: "what does an insect see?" and here I am.
Top material there.
Now you know! Thanks :>)
same.
Likewise!
Hahahaha Me 2
Fantastic, informative video. A decade+ later, and this still might be the single most informative video about the insect compound eye on youtube.
Thank you! :>)
I am happy you looked up the article. UV vision is one of the interesting features of insect physiology. It also demonstrates how expanding sensory perception allows for unexpected perspectives on the world. Birds and some insects can "see" the earth's magnetic field and use it for migration, and I cannot imagine what that must look like. Insects can also "see" polarized light and social insects use it for orientation with their nest or food sources. More factlets :-).
Are u like this insect topic ?????
I am a student of entomology and tomorrow I have a presentation to give. This video definitely cleared a few things for me. Thank you.
Thanks for the video! Needed to learn this for a species in a comic i'm developing! This is the most informative video I found for compound eyes on youtube. Thanks again! :)
This is the best explaination I have ever seen thank you so much that I don't have to waste another hour for the topic it helped me alot
Its much more fascinating when its well-explained. You have superb animations as well; they're logical and provide good intuition into how the concept works. Your videos are highly under-viewed. Thank you for sharing your knowledge.
One the most amazing videos I've seen lately. Thanks so much for such awesome content.
Thank you. I appreciate your comment and interest
Thank you Tom for the nice comments. I am happy that you found the videos of interest and edifying. For some reason the idea that insects see the world as multiple single images got promoted to the public and caught on in some sci-fi movies and comics, but it is a fallacy.
Thank you for the education! I don't know why you got downvoted... People hate learning I guess.
i always thought: What benefit would 1000's of the same image server the creature? surely they must process and stitch the image together, or use the light gathered to form a sense of direction and distance
Yep!
Small nitpick. At 0:38 it should be noted that each facet only accounts for a single pixel or two in an insect's vision (because of this, they are known for having really low resolution vision), so you're representation of what they see is also technically wrong. But it's obvious what you were going for.
So the scotopic ommatidia sacrifice image clarity for light sensitivity. Interesting!
Thank you for this amazing video. Going to go watch all of your other videos now.
Thanks for making this video. I've tried a number of books and websites for an understanding of insect vision and all of them were confusing. Your presentation being the clearest was the best explanation of them all and extremely helpful. Much appreciated.
Thank you so, so much for this video! I am taking an entomology class and have read the vision section of my textbook and numerous papers and websites and really couldn't get exactly how the different eyes worked until I watched this video. Then I watched it over and over to be sure I fully understood it. Very much appreciated!
Samantha Gallagher You are welcome. Thanks for letting me know it is helpful. Best wishes for doing well in your course.
Are insects color blind?
+twistedyogert
No, they have color vision. They can see into the UV (300-400 nm) but not well in the yelloq-red spectrum. There are some excellent pictures on Widipedia and videos on RUclips of the world in the UV range. Flowers in particular take advantage of insect vision in the UV by using UV-reflective stirpes (pollen guides) to attract pollinators to the center of the flower region containing pollen.
I thought it was only pollinators that saw in UV, I never knew that all insects saw in the UV spectrum.
I have two questions: Several years ago I was working the night shift as an arc welder. One night I finished a long weld and lifted my welding hood to notice a large dragonfly sitting on my table. I like dragonflies and brushed my hand to scare it away but it didn't respond. It was alive because I could see it thorax going in and out as it "breathed" I finally picked it up and threw it into the air. It tried to fly but it seemed to have no control. It tumbled this way and that and finally hit the ground.
I've wondered if maybe it didn't go blind as a result of the arc light. If id did go blind would it's vision be lost permanently or would it come back like a human's eye adjusts to a dark room after coming in on a bright sunny day?
My other question is generated by this same job. Insects flying into my weld zone was a real problem. The insect would be burned up instantly and its body would be incorporated into the weld. This would mean stopping, grinding out the weld and re-welding. Why would the insects be so strongly attracted to such an intence light sourse. especially ultraviolet, a wavelength they would rarely see? Adding to this, why would insects be attracted to bright light anyway? The sun is the brightest light in the natural world in the day time, but insects don't try to fly into it. If they did they would climb as high as they could and eventually freeze or die from asphyxia. At night the moon would present the same problem. In addition forest fires have been burning for as long as there have been forests. Why haven't insects developed an aversion to fire? Fires produce a lot of infrared light which can be seen as light. Why would an insect fly into something so hot it dies instantly?
I can answer some of your questions, but not all. I cannot say why the dragonfly was disoriented. Possibly it had been blinded by the intense light and I really cannot say if it would be permanent or temporary. Possibly it got near the heat, as well.
As to why insects fly toward your welding which emits UV, in fact, insects are acutely sensitive to UV. They see very well in the 300-400 nm range, which we do not. They are very sensitive to UV, but not to red. Insects do not see into the red spectrum. Blue flowers are insect pollinated; red flowers are pollinated by vertebrate animals (bats, birds). That would explain why they are attracted and fly into your welding - strong UV emission.
We (entomologists) actually use "black" lights to attract insects at night for collecting and sampling purposes. Flowers have UV reflecting lines, which we cannot see called honey guides, that point insects to the pollen and nectar in the flower center. There are some websites that show how different the world looks to an insect in the UV range if you google insect vision and UV.
You ask about the sun and moon. Black-light trap catches are decreased on full moon nights. Apparently, nocturnal insects are less active on moonlit nights or the moonlight offsets the attractiveness of the black light by being a more attractive focal point and distraction to the black light. Or, possibly they are less active because they are better prey for predators on moonlight nights? As to why they don't fly toward the sun, I cannot say for sure, but in the daytime there is ample light all around, and the sun is not the focal point for the light, like the moon or a porch light are, at night.
Larry Keeley Thanks for answering.
@@llkeeley I think that the Dragonfly would have been permanently damaged by the UV light, our eyes have the ability to control the amount of light hitting our retina by adjusting the size of the pupil and plus we have eyelids. The compound eye doesn't have eyelids or the ability to control the amount of light hitting the retinal cells.
@@twistedyogert Insects actually perceive UV wavelengths and "see" things in that region of the spectrum (unlike vertbrates). They do not have eyelids and contractile pupils, but they have expandable shielding pigments that surround the retinula cells and block excessive light (watch all the scenes as these are explained under eye structure and in the scene on diurnal and nocturnal eyes). So I am not sure I agree with the idea of damage to the retinuila cells. I won't discount it but they withstand a lot of light in the daytime with no damage. If the welder was working at night as indicated, dragonflies are diurnal insects and it may have been in a quiescent "sleep" state called torpor. Diurnal insects often hide at night and are quiescent and difficult to arouse, then become active again in the day.
@@llkeeley So the dragonfly "woke up" in response to the UV flash and then "passed out", when he/she didn't see the light anymore.
Wow! Insect sight is kinda like a C.R.T in reverse. Fascinating !!
Thank you very much for this vid - I had to rewind a few times and readhear certain nomenclature, but I appreciate the level of articulation this video achieves. Great job!
Wow, this is informative and amazing. The insect eye is basically a digital camera. There are lenses, pixels arranged into a sensor array, wiring for connecting to the brain (CPU) and insulation between the wiring.
I've actually read articles about creating artificial compound eyes for autonomous UAVs (drones), apparently the sensors mimicking the compound eye don't require as much processing power as an ordinary camera would.
0:20 He says “what” as if someone was staring at him for no reason.
lol.
Dear Dr. Larry,
Thanks so much for creating this high quality, very informative, and detail video. It's pretty easy to understand and the diagrams are excellent. The insect compound eye is really amazing and exciting. I love the part where we get to see what the insect does! COOL! The complexity of nature is jaw dropping! Am I right in assuming the number of Ommatidia vary by species? If so, what species has the fewest? Well, thanks again for sharing this very cool stuff!
Reading a paper on the role of the sevenless gene in PTK signaling in Dmel and its influence on the development of the R7 cell. Your excellent video explains so well what the geneticists did not. Thank you!
You are welcome.
Very informative video.
Really appreciate it.
Great clip! I've been geeking out on compound eyes for the past year, but this was just an awesome breakdown along with the visualizations! Thanks for sharing this!
I loved this - thank you so much for the clear animations and explanations
appriciating vedio and best part is that you give references
Fascinating. I wish I had known about this a long time ago; it resolved quite a few questions.
Thank you. Glad you found it useful.
Thank you for the nice compliment and for subscribing. I am happy that you found the video helpful.
LK
Excellent! I'm preparing a short talk on Polarisation of Light (Physics) and I read that some insects can actually detect polarisation (and use it for orientation). This video is very helpful to understand insect's vision. Thanks!
Hope the talk goes well. Yes, they are reported to detect polarized light and may use it for orientation.
This is called the pseudo-pupil. In large compound eyes there are flattened regions that have closely-packed and aligned ommatidia to enhance the detail of the view. As you go around the eye the black pupil appears to move with you, and these are the ommatidia that you are looking directly into. You are looking straight to the back of the eye and the light is being absorbed probably by both the visual and screening pigments.
Thanks for making this video! I learned so much.
You are welcome. Always happy to hear that they are helpful.
Really great video- reading R-6 something something opsin with no visuals is so much harder to decipher. This was clear and exciting! Thank you :)
Very well-explained video on the ommatidium (ommatidia in plural) of arthropods, especially insects.
Mr. Keeley, thank you for your detailed synopsis on the photopic omnitidium.
You are most welcome. I hope you found it both informative and useful.
LK
Wow...well made video!!!
The video with its animation and its information is exceptionally well done and certainly helps a lot to understand how insects see.
R.
You are correct, they have a merged image, like a mosaic. As shown the image of far objects are blurry because the eye focal length is for close objects and is not adjustable. Also the ommatidia surround the head so bees would see in nearly 360 deg. Insects see into the UV but not much in red wavelengths. Flowers petals have UV reflective lines called "nectar guides" that point to the heart of the flower and pollen. Bees also detect polarized light for navigation. Try googling these for more.
Not sure where you perceive there to be a blind spot? At ommatidial junctions? Between the primary sensory information at the cornea and the final "experience" of the view in the brain are 3 levels of synaptic integration that would permit perception of a single, unified image within the brain.
Thank you. That is my goal, and I am happy it was successful for you. Best wishes in your studies.
Very informative video, thanks!
That was a great video, thank you.
It would appear as a blend. Each ommatidium would be like a pixel. Since the lens is "near-sighted" it would be a blur of varying degree of brightness. The difference between adjacent ommatidia is what is relevant. The insect eye is most sensitive to movement not a detailed view. Obviously the more ommatidia, the more definition-like jpg vs bmp. E.g. mantids, dragonflies w/many ommatidia are acutely sensitive to moving prey. At the brain level it is probably an integrated, but blurry view
Thanks a lot for this video, it helped clear up a lot of confusion 😊
Fascinating, thank you for this excellent presentation! I thought that insect brains might make compensations similar to the human brain, and that the vision might not be perceived as mosaic. How is it known that this is how it's perceived?
This is something I’m existentially struggling with. Suggested video includes typical pop science countdown video of different animals and their perspectives. I can’t even click on it because I have no answer to your last question. I’ll need to read more literature. It really really pisses me off that these random assumptions about a biological phenomenon made by simply word of mouth and the media picks up whatever sounds coolest.
Yes, I am aware of that for the vertebrate eye. I think it is where the optic nerve emerges. For insects, each ommatidium is like its own eye. See the video on structure: each ommatidium has a lens, a cone to focus light on the receptors (rhabdoms=photoreceptive neurons) and their axons extend to the first synapse behind the eye where the optic nerve forms.Visual fields of adjoining ommatidia also overlap to some degree, based on lens size. I do not know of a similar "blind spot" for insects.
Thank you for the comment. I am happy that you found it useful and informative. You are correct in that different species have different numbers of ommatidia. Primitive species in orders like Collembola (springtails), Protura (coneheads), and Thysanura (silverfish) may have none and no more than 8; dragonflies: tens of thousands (30,000 is one number I found); fruitflies: 700-800. So it is quite variable. It depends on the size of the insect, and habits (active, flying; slow;crawling, etc.).
That's a good question, but no, I doubt there is cause-effect. Hexagons are the most efficient shape for maximum use of a surface area. So a hexagon shape to ommatidia and to honey cells is the best way to pack in the most visual units or honey in a given space, respectively. I think it is a quirk of evolution and chance that they are the same. As I indicated below the mosaic shape is probably only evident in the outer eye, and the brain integrates the view into a continuous image.
Here because I chose not to memorise rather to learn.Thanks for helping alot :)
Hi Larry, this is what I got for the night vision, the explaination is slightly different from yours, can you kindly comment on it? Thanks!
"In dark-adapted eyes (2 h after light off) the rhabdom becomes shorter and fatter, and the aperture around the rhabdom tip widens to 12 µm, which enlarges the rhabdom’s field of view to about 40◦, increasing sensitivity almost six-fold at the expense of resolution. In dark-adapted eyes (2 h after light off) the rhabdom becomes shorter and fatter, and the aperture around the rhabdom tip widens to 12 µm, which enlarges the rhabdom’s field of view to about 40◦, increasing sensitivity almost six-fold at the expense of resolution.
I was just about to ask the same question when I noticed your discussion. I observed the same phenomenon while photographing dragonflies. It's funny how our mammalian brains instinctively interpret this as intentional observation of a single target while the insect is literally just looking around.
beautifully technical yet so instructive, gg
Wonderful, thank you. Using the video to help me study for a third year paper at Massey (NZ), it really sheds some light on the concepts - pun intended!
Thanks so much! How informative. Very well done. I had no eyedea. :-)
I am doing an art projec where i try to record a day from the perspective of a honey bee. This was very helpful. I was afraid bees would see hundreds of images based on each omatidia, but if I understand you correctly they merge the information in their brain to create a single image that is only subdivided into honeycomb-shaped parts to detect contrast and movement. I wonder if you know how many omatidia a regular european honey bee has. I want to be as accurate as possible with depth of field.
On flowers, the streaks on the petals and the bulls-eye appearance leads to the honey and pollen in the center that is food for the insect and pollinates the plant. Also, butterfly species that are toxic to vertebrate predators often have bright warning spots on their wings. In males, these spots also reflect UV and flash" on and off like neon lights as they fly. This on-off flash is an attractant signal for females. So the spots both warn vertebrate predators, and signal insect females as mates
Very interesting material!
Are the shielding pigment cells, of nocturnal insects, easily adjusted to fit the current surroundings or are they governed by an internal clock of sorts?
I ask because I've got silverfish(which I presume are nocturnal, due to mostly nightly activity) living in my bathroom, and I wonder how turning on the lights at night impacts them.
Excellent question.We see from approx 400-650 nm wavelength (blue to red) insects see from approx. 300-550 nm) (UV to green-yellow). So they can see into the UV, which we cannot and they do not see the red very well, and we do,
To see what insects see vs vertebrates, google "ultraviolet vision insects" and go to "the bee's eye view" in the UK Daily Mail, near the bottom. It has nice color pix of our view vs insect UV. It is a different worldview. So, yes, they see color well, just different.
I am happy you could see through it! :-) Thanks
Awesome video
This video covers 3 topics: structure, day-night adaptation, & mosaic vision. We know insects see like this by research from many labs, worldwide, on ommatidia ultrastructure, their optic properties, their electrophysiology and insect behavior.Mosaic vision is based on direct microscopic observation of light at the focal points for clusters of isolated corneal lens. Individual ommatidium views become integrated at the brain level by intervening chiasma with convergent synapse. Hope this helps.
Woow,, fantastic
Glad you liked it
There's a spot on your eye where the optic nerve connects, you can find the blind spot by covering one eye, and looking at a piece of blank paper with a colored dot on it.
If you move your focus to a certain position, the dot will vanish, even though it should be near the center of your vision
Good video, gotta have a lot of patience for it and I doubt I could remember all the technical terms, but good illustration of insect sight.
I'm wondering if you could create an insect eye as a large working model from this somehow, using some sort of clear plastic and a hemisphere with grids/slots for ommatidia? I wonder if anyone's built anything like that.
Yes, I believe it would. Good luck on that.
Fantastic 😊
Awesome vid. I had always suspected that the "insect view" representation of many smaller images was wrong.
Agreed, why would a fly need to see hundreds of fly-swatters when there is only one?
I learned and am appreciated.. thank you for sharing..
You are welcome.
Interesting video. Thanks for sharing.
Would a single ommatidium be capable of resolving the contrast between the sky and tree line/water, or would it appear as a blended mix of the two?
Short version small eye pieces combine to make a big eye. Also never thought I would feel like I'm in class while sitting on my couch.
You are welcome, I am happy to hear you found it of interest.
thanks for the article
Very good and informative video
Thank you, happy you found it useful
Because they are interesting and unique animals! :-)
+Larry Keeley, the video was very instructive and useful for me. Thank you for making it public.
Could you clarify a point? The illustrations depict each ommatidium having multi-pixel resolution. This might be consistent with each ommatidium having 7-8 retinula cells. If the crystalline cone has high transparency, the retinula cells could detect 7-8 pixels per ommatidium. If the photoreceptor molecules within each retinula cell align, say, along or perpendicular to the radius from the center of the ommatidium, this could explain the detection of polarization.
If the crystalline cone is more translucent than transparent, the light hitting the retinula cells would be an average of what appears "out there" and the bundle would act as a single pixel. Consistent with that, one of your comments about two years ago stated that each ommatidium provides a single pixel to the brain. This demands the question, why 7-8 retinula cells? Why not four or even one? (I suppose the need to detect polarization would still require at least four; and it's probably a safe assumption that multiple retinula cells enable detection at multiple wavelengths.)
Thanks for considering my question.
I imagine the number of pixels is determined by the number of rhabdoms per ommatidium. Since each ommatidium has only one rhabdom, I would infer than each ommatidium only provides one pixel of the compound image, not several. Regardless, the ommatidium would not provide the high resolution images he showed in the video.
it is difficult to understanding while reading in the book ...this video helps a lot ...simply explanation cachie points ..clearly understanding...
Happy to know it helped clarify some issues.
LLK
sir ,,do the insects feel pain??????
sir i am doing msc in entomology in india ...my question in larval stage the insect looks like ugly ..but once its become adult it become beautiful like butterfly .what is the reason behind this.. and another question is do the insects have memory?????please clarify me sir...
Larvae are eating machines for growth. Hence, they want to stay localized and hidden near a supply of food, and be ugly so as not to be eaten themselves, while they feed and grow. Adults on the other hand are for reproduction and dissemination of the species. So they have adaptations of body structures used for mate finding (such as flying) and attraction (colors, cuticle ornamentation, pheromones, etc) and finally egg laying for females to disseminate the individuals and maximize environmental potential.
As to memory, there is some evidence that some of the social insects might learn and actually "teach" others. However, most species' behavior is probably reflexive stimulus-response. There is little need for memory (and learning) if you do not live long.
Nearly all living organisms move away from noxious stimuli. Whether they have specialized nervous cells or are a single-celled organisms like a Protozoa. Pain is a subjective concept that we as humans (and all higher animals with developed nervous systems) recognize. The reason for pain is to warn the organism that they are in danger and need to pay attention as their survival could be threatened. Since insects have developed nervous systems, I would speculate that yes, they do feel discomfort and since in my experience, they do evade "danger" -- which might involve damage and pain. That said, I doubt that they contemplate it as a threat to their life, as we recognize when we feel serious pain. So I suspect they detect pain, but at a different level of consciousness. Many insects do not respond very dramatically to injury, so since it is so subjective, it is hard to know if it plays much role in insects. Much of insect behavior is based on a stimulus-response reflex, rather than contemplation. I do think they experience discomfort, whether they consider it pain--????
Thank u brother.
U helped me a lot.❤❤❤
ধন্যবাদ ভাই।।।।।
Happy to know I could be of assistance.
Why can't honeybees see the color red?
They have trichromatic color vision like we do, and most people can see red, green, blue, and different combinations of those wavelengths, creating the full rainbow.
Bees are capable of seeing green to UV wavelengths but not red.
So where does Ocelli come into this, and do they function the same? Cool video if I may
Ocelli are quite different . They are a single lens with multiple photoreceptors and are thought to be sensitive to light-dark but not to form. They might play a role in maintaining stability in flight . Check out Wikipedia for a more detailed explanation.
Thnx 4 video
Anyone 2019
yep
yep
How do their eyes shine during the night??? is there any involvement of the crystalline tract?????
Perfect explanation
Yes, what I am showing is what they perceive at the level of the retina - the back of the ommatidium There are several levels of synaptic integration before the visual receptor signal gets to the brain to fuse the view into a unified pattern. However, each ommatidium views the scene from its perspective in the eye and cutting across ommatidia (movement) is mainly what insects are most sensitive, not a detailed view. They see best broken patterns and edges that transect adjacent ommatidia.
Very Helpful !
Thank you happy to help
These tiny lenses should have very large depth of field, so maybe it doesnt matter that they cant change focus... a large aperture lense like that in our eyes, needs to change focus, because the depth of field for a larger aperture lens is alot shallower.... So maybe the facetted eye sidesteps the need to focus all together...
I knew it couldn't be true that an insects sees multiple images of the same scene per eye! How would that sort of vision be of any use to the insect? That would be the next best thing to being blind. The only issue I have upon seeing this vid is, I doubt pretty seriously that insects have a grid pattern superimposed upon their field of vision. Don't you think their brains/nervous systems would resolve this into one clean image?
I know that arthopods in the ocean also have either superposition or apposition compound eyes, do the shielding pigments in other arthropod classes retract just the same? And what about deep sea arthropods where light doesn't change with the sun but only changes when bioluminescence is present? Or is the retraction (or absence) of the shielding pigments a permanent state?
Sorry I have no idea. I have never seen any studies for oceanic Arthropods.
I wonder if an insect really sees the world in pixels. I rather think that its brain assembles all the individual pixels into a coherent image.
Good video
Hi Larry, great video. What I always wondered, even more then to how/what they see, is how fast they must perceive the world small as they are. i.o.w. how slow they must see us move.. wouldn't that be interesting too? As their eyes are sensitive to motion, this speedfactor must influence the theory on how good they actually see big time i'd say. As they have more time to view things, because they perceive the world in slo-mo.. pity for them their 'direct' enemies do too.
@grimcity You are welcome happy to have been of assistance
L. Keeley
Thanks, very interesting!!
Hm… does it mean compound eyes are very good at seeking out drones?
What do you think of thie relationship between the haxagonal shape of the honeycomb in a bees nest and their eyes? I wonder if the ability of them to create the seeming perfect hexagonal pattern has anything to do with their eye structure.
It actually has to do with geometry. If you want to pack lots of polygons together on a plane the hexagon both interlocks with other hexagons so there’s no wasted space and it approximates a circle so it has the best area to perimeter ratio. Bees use it in hives because it gives them the most space inside a cell for the least amount of Bees wax wall and the cells interlock. Probably a similar reason for why omitidia are hexagonal
well explain! thankssss
Soo helpful video
Thank you
Contrary to this, I would expect that the sharpness of the image is independent of distance in the compound eye, albeit with magnification increasing as distance to the eye decreases. 10:20
Thanks ❤️ it
Thank you sir
I wonder if you reared a group of larva in an oyygen rich environment if how many generations untill large offspring would result?
When you depict "how an insect would see it", what is your basis for having the lines between what each "eye" in the compound eye sees? We have two eyes and rarely do we ever see a line distinguishing the field of vision between them... And that is two different eyes. Wouldn't it similarly be perceived without the "framing" by the insect within the same eye?
Sebastian
You raise an excellent point and I think you are likely correct. Let me explain. Insect vision through the compound eye has been illustrated frequently in the "popular press" and movies that insects "see" a broken, scene because of the hexagonal facets that comprise the eye. And that each facet "sees" the same thing repeatedly, and that is not true. The insect sees a mosaic of a single scene.
What I was trying to demonstrate is that each facet sees the visual scene based on its configuration in the eye and its field of vision and focus. The easy way to show this is to show each facet "looking" at its field of vision in the mosaic with the facet edges showing. Actually, what the insect "sees" is, probably, exactly what you suggest. Although each facet does have its own neurons that detect and transmit the light entering that facet, the neurons undergo synapses before they enter the visual centers of the brain so that the signals of each facet can become combined into an overall "scene" at the level of conscious comprehension by the brain. Therefore, like us, they see with each facet but integrate and fuse the overall scene into something more comprehensible when it is actually perceived at the conscious level that leads to behavior.
Of course, I could be wrong and they do see the outlines of the facet -- just as you and I cannot know what each other "sees" when we look at something. Sense perception is unique to the perceiver and although we all think we see, smell, taste etc. alike; we also know that is not true. For example, we know that some individuals have color blindness or age-related sensitivity to different wavelengths of sound.
We do know that insects are most sensitive to edges of objects and patterns and movement - things that cut across ommatidial fields of vision, but whether they actually perceive the boundary of their own ommatidia is unlikely -- as you point out. But, showing the boundary makes it easier to explain and understand in the tutorial. Thanks for the question as it is a good one and allows me to make the point about individual differences in sensory perception, i.e. perception is in the "eye" of the "beholder".
@@llkeeley Thanks you for your response. We're I to speculate, I would venture to say that the compound eye would likely be more sensitive to certain forms of movement (I don't want to assume all movement) for one two reasons. First, when something completely disrupts the sight in one of our eyes, it is impossible to ignore. In similar manner, an entire "facet" ("eye within an eye" if you will) would probably irritate or draw immediate attention from the insect. The second reason I hypothesize this is because it may be that so long as something does not move between the borders of the facets, the insect sees a single image much like we do with both our eyes. However, if something hits the sweet spot between where multiple facets see it, it might be like when something moves between our eyes (into just the right spot), causing us to have to immediately readjust and refocus. The object now had our undivided attention.
This is purely creative speculation on my part but it would seem to make sense. I would be interested to hear your thoughts.
I agree. Anything in one facet appears static but when it moves to the other then it is "noticed" Since insects cannot roll their eyes it would have to move from one to the other facet to be perceived as moving.
@@llkeeley What's interesting is that this almost implies that thier visual acuity is roughly as detailed as the image of a yard viewed from a moving vehicle through the slats of a fence (if you have ever experienced this phenomenon). The colors are present but the "lines" are... Not "blurred" exactly but required far more strain to perceive.
Your presentation seems to suggest that insects see shapes within each facet of their eye. However, your explanation of the anatomy of the eye suggests that they see a single dot per facet.
If I have this wrong, please explain.
I state right in the first scene that the single-facet repeated view of the entire scene is what "popular" concept, but that this is erroneous. What they really see is similar to what we see in that each facet sees a part of the view from its own perspective not repeated entire images in each facet. I saythat in the start of the first scene and describe it detail in the entire last scene.
very informative
Hamdar7 thank you. Happy you found it useful.
L.Keeley
Also of interest is that the word for 'ommatidium (ommatidia)' in Chinese is xiǎoyǎn 小眼.