Johnny Pneumatic
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Can endothermic animals evolve heat vision like ssome insects and snakes have? Could IR cones go right along with the other cones in the eye?
IR vision and Endothermic Animals
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Atlas
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Pit vipers have evolved this separate sense. I think of it as a sense like our 5 senses and requiring a special sensing organ. Which to me means that it's unlikely that the eye would evolve to do double duty.SkepticJ said:
However, Infrared and visible light are EM waves just of different frequencies. I think that different animals could have an expanded or reduced visual spectrum just as certain animals hear better or worse than we do.
As far as adapting to waves and vision go... I believe alligators and crocadiles have a sense awareness of waves propagating on the surface of water. They do not need to see their prey they can tell from the waves propagating from a swimmer's splash or wake how to track right to it.
I just looked up a site which says they may use the sense organ to "see" prey underwater. A swimming fish will excite the pressure sense organs in a way that a rock will not. Actually scientists aren't sure exactly how it all works.
Johnny Pneumatic
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I am aware that snakes use heat sensing pits not their eyes for this, I should have been more clear. What I'm asking is could cones for heat evolve like cones have for red, blue and green light. There are also the rods that detect amounts of light and dark. The reason for the endothermic animal part of the question is--> can an animal that has a temp. higher than the surrounding environment see the environ's and other endothermic animal's heat or will the own animal's heat set off the IR eye cones so nothing in the environment can be seen? I can think of no warm animal that can see heat. Snakes, insects, scorpions etc. are all ectothermic(have the same temp. as the environment that they live in) does this mean it can't work in warm animals? I should think cats, dogs and many other mammal predators would find this ability to be a survival advantage(therefor it would be expected to have evolved by now if possible).
AK-Dave
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I can't answer the question you want answered, but your question got me thinking about the evolution of eyes and how it might relate to the sensory organs of pit vipers. My understanding of the evolution of eyes is that each time eyes evolved (I read somewhere that eye functionality evolved independently in several different genetic lines, which matches my observations of different types of animals), they started as light sensitive patches on the surface of the skin, then evolved into light sensitive patches in pits, then evolved some kind of lens mechanism, and so on until we got the different types of eyes that exist now. Is it possible that the pits on pit vipers are primitive eyes that are sensitive to infrared radiation? And is it possible that over time, these will evolve into a second set of complex eyes that can see heat, complete with a focusing mechanism similar to their normal eyes?
Just something that popped into my head. Feel free to disregard if it doesn't make sense. I'll just blame it on the wine.
Just something that popped into my head. Feel free to disregard if it doesn't make sense. I'll just blame it on the wine.
neutrino_cannon
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We should specify, an ectotherm is only an animal that relies on outside heat sources, and an endotherm one that relies upon internal heat sources. A constant body temperature is desirable because enzymes work optimally within a narrow range of temperatures. For the most part animals with a constant body temperature keep it constant by having a ridiculously high metabolism, and consequentially a lot of waste heat pouring off of them. This is, by the way, a gross oversimplification of things, and there are a great deal of fascinating exceptions I'd love to list.
Animals that do rely on external sources of heat to maintain body temperature (which they really don't, they just do their best) are still going to have waste heat, they'll just have less. Entropy remember? Just don't expect to get warm sleeping in a big ball of snakes (which rattlers are known to do), there's not *that* much waste heat.
How does this relate to IR vision? Indirectly. Hot objects emit infra red, although heat and infra-red aren't the same thing! It is also prudent at this point to mention goldfish, which can see in low-red, which is a range of frequency just above infra red. Snakes use clusters of temperature sensitive cells which is less efficient, though there is no paucity of snakes around Denver, so I'm forced to conclude it works. Theoretically though, if an animal is pouring off heat, it will blind its own IR receptors.
I'm not sure if this is a reasonable assumption. Very large animals, whether high or low metabolism, have lower caloric consumption rates per unit mass than smaller ones. This is why you should snuggle with a bunch of rabbits, rather than an elephant of equivalent mass, to stay warm at night. I hope you don't find it disturbing that the only example I can think of to explain relative animal metabolisms involves sleeping with them to keep warm.
A very large animal, therefore could have some sort of IR vision with much less interference from its own body. In fact, I'm not sure a small one couldn't do the same thing, it's not like you couldn't see if you were glowing brightly, quite the opposite, you'd be your own lantern in the dark. Conventional wisdom would suggest that this is somehow a problem, and frankly I can't see why it is.
Assuming that seeing in a frequency that you radiate in is a problem, I would suggest that the seeing organs be cooled off. It's hardly without precedent for certain organs to have much significantly lower local temperatures than the rest of the body. What on earth could N_C be talking about? Well, if you're a guy, it's easy. Just take your pants and undergarments off, and there you go. Yes, that's why those things dangle like that, sperm manufacture works optimally at a slightly lower temperature. It think this also explains the odd reaction to cold water the little fellows demonstrate. Don't ask me to comment on what this means tight underwear will do to your fertility, I frankly have no idea is it makes a difference or not. It would be interesting, however if latex fetishists were heating up their nether regions enough that they couldn't reproduce, thus causing their extinction in a few generations and leaving the S&M market totally dominated by those leather folks.
That leaves a large animal with eyes cooled by some means and the rest of its heat dissipation machinery (those wrinkles on elephants do serve a purpose) well aft of said eyes. This isn’t that far fetched, the eyes are close to the brain and the brain needs cooling. Perhaps some sort of specialized sinus tissue could do the job. The localized wrinkles near the arse end of the beast could also make nice display ornaments, especially since they would radiate in the IR so much. Just exactly what combination of pressure would conspire to create such a beast is beyond my imagination.
Animals that do rely on external sources of heat to maintain body temperature (which they really don't, they just do their best) are still going to have waste heat, they'll just have less. Entropy remember? Just don't expect to get warm sleeping in a big ball of snakes (which rattlers are known to do), there's not *that* much waste heat.
How does this relate to IR vision? Indirectly. Hot objects emit infra red, although heat and infra-red aren't the same thing! It is also prudent at this point to mention goldfish, which can see in low-red, which is a range of frequency just above infra red. Snakes use clusters of temperature sensitive cells which is less efficient, though there is no paucity of snakes around Denver, so I'm forced to conclude it works. Theoretically though, if an animal is pouring off heat, it will blind its own IR receptors.
I'm not sure if this is a reasonable assumption. Very large animals, whether high or low metabolism, have lower caloric consumption rates per unit mass than smaller ones. This is why you should snuggle with a bunch of rabbits, rather than an elephant of equivalent mass, to stay warm at night. I hope you don't find it disturbing that the only example I can think of to explain relative animal metabolisms involves sleeping with them to keep warm.
A very large animal, therefore could have some sort of IR vision with much less interference from its own body. In fact, I'm not sure a small one couldn't do the same thing, it's not like you couldn't see if you were glowing brightly, quite the opposite, you'd be your own lantern in the dark. Conventional wisdom would suggest that this is somehow a problem, and frankly I can't see why it is.
Assuming that seeing in a frequency that you radiate in is a problem, I would suggest that the seeing organs be cooled off. It's hardly without precedent for certain organs to have much significantly lower local temperatures than the rest of the body. What on earth could N_C be talking about? Well, if you're a guy, it's easy. Just take your pants and undergarments off, and there you go. Yes, that's why those things dangle like that, sperm manufacture works optimally at a slightly lower temperature. It think this also explains the odd reaction to cold water the little fellows demonstrate. Don't ask me to comment on what this means tight underwear will do to your fertility, I frankly have no idea is it makes a difference or not. It would be interesting, however if latex fetishists were heating up their nether regions enough that they couldn't reproduce, thus causing their extinction in a few generations and leaving the S&M market totally dominated by those leather folks.
That leaves a large animal with eyes cooled by some means and the rest of its heat dissipation machinery (those wrinkles on elephants do serve a purpose) well aft of said eyes. This isn’t that far fetched, the eyes are close to the brain and the brain needs cooling. Perhaps some sort of specialized sinus tissue could do the job. The localized wrinkles near the arse end of the beast could also make nice display ornaments, especially since they would radiate in the IR so much. Just exactly what combination of pressure would conspire to create such a beast is beyond my imagination.
neutrino_cannon said:
That's the crux of it, NC. If your "IR Eye" is the same temperature as your body, it will be flooded with IR photons on a blackbody radiation spectrum from your body, which is UP CLOSE.
Detecting something else AT THE SAME TEMPERATURE will require that the other thing be really big, and really close. In other words, it won't provide any useful information.
So, if you want this to work, you have, especially in the tropics, ACTIVE cooling to make this work. No cooling, the retina will emit the photons that destroy the dyes that absorb the photons so fast and so much that you'll get no useful vision.
pgwenthold
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A great opportunity for me to discuss the beauty of the eye, again.
Our ability to detect visible radiation obviously gives us a huge advantage. However, from a chemistry standpoint, detecting visible is a big challenge. Every organic molecules absorbs in the IR, and all conjugated systems will absorb in the longer UV regions. However, the visible region is an extremely difficult region to work in, because few organic molecules can absorb light at those wavelengths. Nature has found rods and cones to do it, but we still need to recognize that it is a very special situation. If you go to an organic lab, most of the products are white or colorless (except for the black tar). Colored organic compounds are actually very notable, and are immediately considered as potential dyes.
OTOH, as I said, all organic molecules absorb in the IR, and most biological molecules will have groups that absorb in the UV. Therefore, we already have IR detectors in our skin. Sure enough, when your skin warms near the fire, it is from the absorption of IR radiation. Because of our IR detecting ability, we know for example when we get close to a fire, even if we are blind. In the same way, our skin is an IR emmitter, and gives off IR radiation.
Similarly, our skin is a UV detector. Sunburn is caused by the absoprtion of UV light.
Now, I don't know about the IR pits on a snake, but as has been noted, they will have to detect in regions outside of normal organic molecule vibrational frequencies, because even though the snake is cold-blooded, organic molecules emit at ambient temperatures, even when they are relatively low (the difference between 80 degrees and 32 degrees may seem large, but in an absolute sense it is less than a 10% difference (300 K vs 273 K). Therefore, even at 32 degrees, a snake skin will emit extensively in the IR. I'm guessing that the snakes IR pits are actually more in the near IR region, more in range of 1 - 2 microns. If molecules that absorb in the visible are rare, things that absorb in the near IR are very, very rare. When I hear of such things, I generally assume an open-shell system, like a free radical or a radical-ion, that can undergo a one-electron transition without having to unpair itself. However, open-shell molecules are also very reactive, and therefore don't make good detectors. Thus, being able to detect in the near IR requires very special make-up.
Our ability to detect visible radiation obviously gives us a huge advantage. However, from a chemistry standpoint, detecting visible is a big challenge. Every organic molecules absorbs in the IR, and all conjugated systems will absorb in the longer UV regions. However, the visible region is an extremely difficult region to work in, because few organic molecules can absorb light at those wavelengths. Nature has found rods and cones to do it, but we still need to recognize that it is a very special situation. If you go to an organic lab, most of the products are white or colorless (except for the black tar). Colored organic compounds are actually very notable, and are immediately considered as potential dyes.
OTOH, as I said, all organic molecules absorb in the IR, and most biological molecules will have groups that absorb in the UV. Therefore, we already have IR detectors in our skin. Sure enough, when your skin warms near the fire, it is from the absorption of IR radiation. Because of our IR detecting ability, we know for example when we get close to a fire, even if we are blind. In the same way, our skin is an IR emmitter, and gives off IR radiation.
Similarly, our skin is a UV detector. Sunburn is caused by the absoprtion of UV light.
Now, I don't know about the IR pits on a snake, but as has been noted, they will have to detect in regions outside of normal organic molecule vibrational frequencies, because even though the snake is cold-blooded, organic molecules emit at ambient temperatures, even when they are relatively low (the difference between 80 degrees and 32 degrees may seem large, but in an absolute sense it is less than a 10% difference (300 K vs 273 K). Therefore, even at 32 degrees, a snake skin will emit extensively in the IR. I'm guessing that the snakes IR pits are actually more in the near IR region, more in range of 1 - 2 microns. If molecules that absorb in the visible are rare, things that absorb in the near IR are very, very rare. When I hear of such things, I generally assume an open-shell system, like a free radical or a radical-ion, that can undergo a one-electron transition without having to unpair itself. However, open-shell molecules are also very reactive, and therefore don't make good detectors. Thus, being able to detect in the near IR requires very special make-up.