Recent insights into how animals see without eyes reveal that vision and light-detection are older and more widespread than biologists previously realized
Some eyeless animals perceive light. Likewise, some animals with eyes—even rather sophisticated eyes—rely on other body parts to see....[More]
MORE TO VISION THAN MEETS THE EYE:
Some eyeless animals perceive light. Likewise, some animals with eyes—even rather sophisticated eyes—rely on other body parts to see. Here are six striking examples of animals that have surprised researchers with eyeless sight.
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Compound eye of the Antarctic krill Euphausia superba. Photo by Gerd Alberti and Uwe Kils, via Wikimedia Commons
NO EYE IN URCHIN:
Sea urchins respond to light in various ways: they might change color, twitch their spines or move toward or away from light. Until recently, scientists were not certain how urchins detect light; no known species has eyes of any kind....[More]
NO EYE IN URCHIN:
Sea urchins respond to light in various ways: they might change color, twitch their spines or move toward or away from light. Until recently, scientists were not certain how urchins detect light; no known species has eyes of any kind.
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Kirt L. Onthank, via Wikimedia Commons
TUBULAR VISION:
It turns out that the ends a sea urchin's tubular feet are pockmarked with opsins, the same kind of light-sensitive proteins our own eyes depend on....[More]
TUBULAR VISION:
It turns out that the ends a sea urchin's tubular feet are pockmarked with opsins, the same kind of light-sensitive proteins our own eyes depend on. A sea urchin's hundreds of feet may act as one giant compound eye. Opsins are stained red in this juvenile urchin.
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Photo courtesy of Sam Dupont, University of Gothenburg
STING OPERATION:
Like sea urchins, tiny relatives of jellyfish called hydras also respond to light even though they lack eyes. Recently, scientists confirmed that hydras have opsins in their tentacles, specifically in their stinging cells, known as cnidocytes....[More]
STING OPERATION:
Like sea urchins, tiny relatives of jellyfish called hydras also respond to light even though they lack eyes. Recently, scientists confirmed that hydras have opsins in their tentacles, specifically in their stinging cells, known as cnidocytes.
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Oinari-san, via Wikimedia Commons
SHADOWBOXER:
In this image of a hydra tentacle, cnidocytes are stained red. Hydras sting with greater force in dim light than in bright light, perhaps because they recognize shadows as signs of prey or predators....[More]
SHADOWBOXER:
In this image of a hydra tentacle, cnidocytes are stained red. Hydras sting with greater force in dim light than in bright light, perhaps because they recognize shadows as signs of prey or predators. Since hydras belong to one of the oldest groups of animals, the Cnidarians, the origins of vision likely stretch further back in time than anyone realized.
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Image courtesy of David C Plachetzki of the University of California, Davis
COLORLESS CUNNING:
Although octopuses, cuttlefishes and some squid can match the texture and color of almost anything in their environment, their relatively large eyes cannot see color....[More]
COLORLESS CUNNING:
Although octopuses, cuttlefishes and some squid can match the texture and color of almost anything in their environment, their relatively large eyes cannot see color. Scientists recently discovered, however, that these mollusks express opsin genes throughout their skin.
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Leonard Low, via Wikimedia Commons
PIXELATED PIGMENTS:
Octopus, squid and cuttlefish skin is also peppered with chromatophores—elastic sacks of pigment that expand and retract, allowing the mollusk to change its color....[More]
PIXELATED PIGMENTS:
Octopus, squid and cuttlefish skin is also peppered with chromatophores—elastic sacks of pigment that expand and retract, allowing the mollusk to change its color. Some scientists propose that opsins work with chromatophores in an unknown way to detect and mimic the color of nearby objects.
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Minette, via Wikimedia Commons
DOWN TO EARTH:
Although tiny worm-like nematodes named Caenorhabditis elegans live in complete darkness in the soil, scientists recently discovered that they have light-sensitive neurons and consistently wriggle away from light, an adaptation that likely helps them avoid the dangerous surface world....[More]
DOWN TO EARTH:
Althoughtiny worm-like nematodesnamed Caenorhabditis elegans live in complete darkness in the soil, scientists recently discovered that they have light-sensitive neurons and consistently wriggle away from light, an adaptation that likely helps them avoid the dangerous surface world.
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National Human Genome Research Institute, via Wikimedia Commons
HINDSIGHT:
Japanese yellow swallowtail butterflies can see with their rear ends. More accurately, they have two light-sensitive neurons called photoreceptors on their abdomens, right next to their genitals....[More]
HINDSIGHT:
Japanese yellow swallowtail butterflies can see with their rear ends. More accurately, they have two light-sensitive neurons called photoreceptors on their abdomens, right next to their genitals. These light detectors are essential for swallowtail butterfly sex and reproduction.
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KENPEI, via Wikimedia Commons
BUTTERFLY KISSES:
Studies suggest that male swallowtail butterflies rely on their hindsight to cozy up to females during mating and that female swallowtails depend on light-detection to confirm that they have properly extended their ovipositor—the organ with which they attach eggs to leaves....[More]
BUTTERFLY KISSES:
Studies suggest that male swallowtail butterflies rely on their hindsight to cozy up to females during mating and that female swallowtails depend on light-detection to confirm that they have properly extended their ovipositor—the organ with which they attach eggs to leaves.
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Autumn Snake, via Wikimedia Commons
OUT OF SIGHT:
Scorpions instinctively avoid light. During the day, the eight-legged arachnids seek shelter beneath rocks, in underground crevices or in people's boots.
Most scorpion species have a dark, waxy exoskeleton that looks like black or amber armor in daylight. If certain wavelengths of ultraviolet (UV) light strike a scorpion, however, it glows an eerie neon turquoise because of fluorescent molecules in its cuticle....[More]
NIGHT LIGHT:
Most scorpion species have a dark, waxy exoskeleton that looks like black or amber armor in daylight. If certain wavelengths of ultraviolet (UV) light strike a scorpion, however, it glows an eerie neon turquoise because of fluorescent molecules in its cuticle.
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Jonbeebe, via Wikimedia Commons
GO WITH THE GLOW:
Some preliminary evidence suggests that scorpions can detect UV light with their skin, even when their eyes are covered. Alternatively, scorpions may be attuned to the green light in their armor's turquoise fluorescence....[More]
GO WITH THE GLOW:
Some preliminary evidence suggests that scorpions can detect UV light with their skin, even when their eyes are covered. Alternatively, scorpions may be attuned to the green light in their armor's turquoise fluorescence. Using its entire body to detect light, rather than its eyes alone, might improve a scorpion's chances of finding shelter during the day.
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Image courtesy of Douglas Gaffin, University of Oklahoma
YES! Send me a free issue of Scientific American with no obligation to continue the subscription. If I like it, I will be billed for the one-year subscription.
This reminds me that many creationist say things like "how can something as complex as the human eye come about by chance? Thus, there must have been a divine creator." I always thought that was a funny argument. I wonder if they are still using that argument as support for creationism.
They are. I agree, Logically it's a terrible argument. Creationist tend to use the general argument that oh, since something is complex, that means it was designed on the faulty basis that complex things can only be designed by intelligence since in our daily lives we see that the complex things we use were designed by humans.
I always love those slide shows and articles about curiosities in certain species. It's amazing what sort of things arise with natural selection.
What gets me about the examples that 'creationists' choose to 'prove' their belief that all living species appeared out of nowhere in one day is that they are almost all taken from... 'The Origin of Species'! (All online now - see http://darwin-online.org.uk/EditorialIntroductions/Freeman_OntheOriginofSpecies.html.) But of course (sadly, like some biologists, who are often ignorant of scientific history) the 'creationists' have usually never read anything Darwin wrote, let alone tried to understand it, let alone read any biological research since. Darwin specifically mentions complex structures like eyes as a challenge to his theory in Chapter 6 - but he then plausibly discusses how they might have arisen. And the evidence since has shown he was basically right.
This creationist would like to attack the evolutionary problem that is the eye, not by quoting Darwin (which seems to be politically incorrect on this web page) but by quoting a late French zoologist:
We know absolutely nothing about the evolution of the eye of the vertebrate, and embryology is of little help. The problem is to know whether random mutations could have given rise to an organ requiring, because of its complexity, a considerable number of data for its elaboration. The number of mutations must have been enormous for adequate ones to occur at a given point, by chance and to enable the organ to function. We need not belabor the diversity of the transparent parts, on the relationships between the intraocular fluid (aqueous humor) and the venous system...among others. The complexity of the retina, of the sheaths, etc., need not detain us either; all this is extremely well known, but we must say that no recent publication inspired by Darwinism even mentions it.
[Prof. Pierre-P. Grassé. 1977. EVOLUTION OF LIVING ORGANISMS: Evidence for a New Theory of Transformation. New York: ACADEMIC PRESS, p. 105]
Bill_Crofut has evidently never heard of Richard Dawkins.
He has published a straight-forward evolution of the vertibrate eye. Yes, humans, eagles, horses, bats, snakes and fish ALL have exactly the same eye architecture. Details vary. Check out wiki "eye."
Bill Crofut has indeed heard of Prof. Richard Dawkins:
"There is nothing original in the objections deployed by [creationist] books, just the old favourites ("The eye is too complicated to have evolved by blind 'chance'", and the rest) that Darwin himself raised - and demolished."
[1985. What was all the fuss about? NATURE Vol. 316, p. 683]
He's also heard of Prof. Pierre-P. Grassé:
We know absolutely nothing about the evolution of the eye of the vertebrate, and embryology is of little help. The problem is to know whether random mutations could have given rise to an organ requiring, because of its complexity, a considerable number of data for its elaboration. The number of mutations must have been enormous for adequate ones to occur at a given point, by chance and to enable the organ to function. We need not belabor the diversity of the transparent parts, on the relationships between the intraocular fluid (aqueous humor) and the venous system...among others. The complexity of the retina, of the sheaths, etc., need not detain us either; all this is extremely well known, but we must say that no recent publication inspired by Darwinism even mentions it.
[1977. EVOLUTION OF LIVING ORGANISMS: Evidence for a New Theory of Transformation. New York: ACADEMIC PRESS, p. 105]
Vision is an amazing thing. The way we think of it is likely much more mental/nervous system than simply what appears to be correctly arranged optics. But we marvel how complex and great the eye is, because what we see impresses our intelligence so much. Might it be that we are not so bright and impressing our senses is actually pretty easy, like the games we play with babies or watching a cat chase a laser dot. Our marvelous vision is quite limited to a narrow slice of the spectrum. Some other animals and maybe plants sense further in either direction than our eyes. Some insects and maybe birds see further into the UV and pit vipers 'see' the IR signature or image of warm prey. Eagles and kin can see as if they were looking through a telescope or binoculars. All eyes are not the same and all are not equal. When we or Darwin or Dawkins are amazed, or not, it may reflect more on our mental stage of development and/or knowledge than on the actual observation. I too love these slide shows showing unusual development and structures that will provide grist for future study. What do these organisms sense with these opsins? How is it integrated into their 'minds'? If we dare call these primitive nervous systems, or lack thereof, minds. What do they see? I find these sorts of questions much more interesting than arguments for or against intelligent design. And these are the kinds of questions science is designed to find answers to. It is axiomatic that you can't prove a negative, so why waste the time or effort?
I don't understand how this can be so surprising to researchers. Humans detect infrared light with our skin, and there is plenty of evidence that many other animal species do the same. It's no great leap to imagine light-sensitive skin cells which detect wave lengths other than infrared.
IT's never fails... a "creationist" trolling on Sciam. Creationism is beyond bogus in any context of evidence-based rationality... aka scientific inquiry... having no evidence to support such absurdities as "irreducible complexity" and "intelligent design". It lies palsied and atrophied in the great shadow of the proverbial mountain of evidence which fully supports the edifice of evolution from many diciplines... genetics being the proverbial icing on the cake that Darwin knew nothing about.
ALL that aside, the evolution of the human eye is absolutely obvious to any but the most "blinded by faith" to the facts. There is just about every anatomical model in extant species... as well as the entire range of evolutionary adaptations in living Mollusks alone. From the basic photoreceptors in Limpets... to the Nautilus's invaginated eye with a liquid cavity and optic nerve... to the Murex with it's refractive lens... to the wonderfully complex eye of cepholopods (e.g. Octopus).
Further, the evolution of the human eye has been nicely worked out by Zoologist Dan-Erik Nilsson. Interestingly, the anatomy of the human eye is less than "ideal" with it's proverbial "blind spot" due to the exit of the optic nerve throught the retina... and the vasculature above the retinal, photo-sensitive cells. The cepholopod retina does not suffer these "design flaws"... LOL! THE final point about creationism/ID is the proponents of such nonsense have been caught red-handed in our courts being dishonest in their means to undermine evolution in the science class. But then again, knowing the history of the patchwork, so-called canonical bible... the redactions and interpolations... the authoritarianism of the early church fathers wherby any means justified their ends... sometimes brutal suppression of competing sects... Inqusitions... that these decptive methods continue today should surprise no one. NOW... Mr. Creationist... tell us again about how the sequence of events in the bible-creation-myths work... the (Olive) Garden... Adam n' his rib spawin' all Homonids... Noah's lil' boat... ZZZzzz... Oh... and if humans are so intelligently designed... why are there like... um... encyclopedic volumes of human medical ailments from congenital anomalies to myriad diseases of every organ system... and up to 30% spontaneous abortive loss during the very basic act of reproduction... not to mention a heap o' ailments primarily due to our upright posture? NEXT!
12. Spin-oza
in reply to American Muse01:11 PM 8/28/12
Thanks Muse. It seems our creationist-troll seems to be utterly speechless or... is plying thier sullied wares... St. Elsewhere:-) Cheers to all who humbly accept our place in this stunning, inexorably evolving Cosmos, free of the blinders and delusions of stale religious dogma!
Re: "NOW... Mr. Creationist... tell us again about how the sequence of events in the bible-creation-myths work... the (Olive) Garden... Adam n' his rib spawin' all Homonids... Noah's lil' boat... ZZZzzz.."
Since that narrative will obviously put you to sleep, allow me to try another approach:
Re: "...[T]he evolution of the human eye has been nicely worked out by Zoologist Dan-Erik Nilsson."
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13 Comments
Add CommentThis reminds me that many creationist say things like "how can something as complex as the human eye come about by chance? Thus, there must have been a divine creator." I always thought that was a funny argument. I wonder if they are still using that argument as support for creationism.
Reply | Report Abuse | Link to thisThey are. I agree, Logically it's a terrible argument. Creationist tend to use the general argument that oh, since something is complex, that means it was designed on the faulty basis that complex things can only be designed by intelligence since in our daily lives we see that the complex things we use were designed by humans.
Reply | Report Abuse | Link to thisI always love those slide shows and articles about curiosities in certain species. It's amazing what sort of things arise with natural selection.
What gets me about the examples that 'creationists' choose to 'prove' their belief that all living species appeared out of nowhere in one day is that they are almost all taken from... 'The Origin of Species'!
Reply | Report Abuse | Link to this(All online now - see http://darwin-online.org.uk/EditorialIntroductions/Freeman_OntheOriginofSpecies.html.)
But of course (sadly, like some biologists, who are often ignorant of scientific history) the 'creationists' have usually never read anything Darwin wrote, let alone tried to understand it, let alone read any biological research since.
Darwin specifically mentions complex structures like eyes as a challenge to his theory in Chapter 6 - but he then plausibly discusses how they might have arisen. And the evidence since has shown he was basically right.
This creationist would like to attack the evolutionary problem that is the eye, not by quoting Darwin (which seems to be politically incorrect on this web page) but by quoting a late French zoologist:
Reply | Report Abuse | Link to thisWe know absolutely nothing about the evolution of the eye of the vertebrate, and embryology is of little help. The problem is to know whether random mutations could have given rise to an organ requiring, because of its complexity, a considerable number of data for its elaboration. The number of mutations must have been enormous for adequate ones to occur at a given point, by chance and to enable the organ to function. We need not belabor the diversity of the transparent parts, on the relationships between the intraocular fluid (aqueous humor) and the venous system...among others. The complexity of the retina, of the sheaths, etc., need not detain us either; all this is extremely well known, but we must say that no recent publication inspired by Darwinism even mentions it.
[Prof. Pierre-P. Grassé. 1977. EVOLUTION OF LIVING ORGANISMS: Evidence for a New Theory of Transformation. New York: ACADEMIC PRESS, p. 105]
Bill_Crofut has evidently never heard of Richard Dawkins.
Reply | Report Abuse | Link to thisHe has published a straight-forward evolution of the vertibrate eye. Yes, humans, eagles, horses, bats, snakes and fish ALL have exactly the same eye architecture. Details vary. Check out wiki "eye."
Bill Crofut has indeed heard of Prof. Richard Dawkins:
Reply | Report Abuse | Link to this"There is nothing original in the objections deployed by [creationist] books, just the old favourites ("The eye is too complicated to have evolved by blind 'chance'", and the rest) that Darwin himself raised - and demolished."
[1985. What was all the fuss about? NATURE Vol. 316, p. 683]
He's also heard of Prof. Pierre-P. Grassé:
We know absolutely nothing about the evolution of the eye of the vertebrate, and embryology is of little help. The problem is to know whether random mutations could have given rise to an organ requiring, because of its complexity, a considerable number of data for its elaboration. The number of mutations must have been enormous for adequate ones to occur at a given point, by chance and to enable the organ to function. We need not belabor the diversity of the transparent parts, on the relationships between the intraocular fluid (aqueous humor) and the venous system...among others. The complexity of the retina, of the sheaths, etc., need not detain us either; all this is extremely well known, but we must say that no recent publication inspired by Darwinism even mentions it.
[1977. EVOLUTION OF LIVING ORGANISMS: Evidence for a New Theory of Transformation. New York: ACADEMIC PRESS, p. 105]
Vision is an amazing thing. The way we think of it is likely much more mental/nervous system than simply what appears to be correctly arranged optics. But we marvel how complex and great the eye is, because what we see impresses our intelligence so much. Might it be that we are not so bright and impressing our senses is actually pretty easy, like the games we play with babies or watching a cat chase a laser dot. Our marvelous vision is quite limited to a narrow slice of the spectrum. Some other animals and maybe plants sense further in either direction than our eyes. Some insects and maybe birds see further into the UV and pit vipers 'see' the IR signature or image of warm prey. Eagles and kin can see as if they were looking through a telescope or binoculars. All eyes are not the same and all are not equal. When we or Darwin or Dawkins are amazed, or not, it may reflect more on our mental stage of development and/or knowledge than on the actual observation. I too love these slide shows showing unusual development and structures that will provide grist for future study. What do these organisms sense with these opsins? How is it integrated into their 'minds'? If we dare call these primitive nervous systems, or lack thereof, minds. What do they see? I find these sorts of questions much more interesting than arguments for or against intelligent design.
Reply | Report Abuse | Link to thisAnd these are the kinds of questions science is designed to find answers to. It is axiomatic that you can't prove a negative, so why waste the time or effort?
doug_pdq,
Reply | Report Abuse | Link to thisYou’ll get no argument from me.
I don't understand how this can be so surprising to researchers. Humans detect infrared light with our skin, and there is plenty of evidence that many other animal species do the same. It's no great leap to imagine light-sensitive skin cells which detect wave lengths other than infrared.
Reply | Report Abuse | Link to thisIT's never fails... a "creationist" trolling on Sciam.
Reply | Report Abuse | Link to thisCreationism is beyond bogus in any context of evidence-based rationality... aka scientific inquiry... having no evidence to support such absurdities as "irreducible complexity" and "intelligent design".
It lies palsied and atrophied in the great shadow of the proverbial mountain of evidence which fully supports the edifice of evolution from many diciplines... genetics being the proverbial icing on the cake that Darwin knew nothing about.
ALL that aside, the evolution of the human eye is absolutely obvious to any but the most "blinded by faith" to the facts. There is just about every anatomical model in extant species... as well as the entire range of evolutionary adaptations in living Mollusks alone. From the basic photoreceptors in Limpets... to the Nautilus's invaginated eye with a liquid cavity and optic nerve... to the Murex with it's refractive lens... to the wonderfully complex eye of cepholopods (e.g. Octopus).
Further, the evolution of the human eye has been nicely worked out by Zoologist Dan-Erik Nilsson. Interestingly, the anatomy of the human eye is less than "ideal" with it's proverbial "blind spot" due to the exit of the optic nerve throught the retina... and the vasculature above the retinal, photo-sensitive cells. The cepholopod retina does not suffer these "design flaws"... LOL!
THE final point about creationism/ID is the proponents of such nonsense have been caught red-handed in our courts being dishonest in their means to undermine evolution in the science class.
But then again, knowing the history of the patchwork, so-called canonical bible... the redactions and interpolations... the authoritarianism of the early church fathers wherby any means justified their ends... sometimes brutal suppression of competing sects... Inqusitions... that these decptive methods continue today should surprise no one.
NOW... Mr. Creationist... tell us again about how the sequence of events in the bible-creation-myths work... the (Olive) Garden... Adam n' his rib spawin' all Homonids... Noah's lil' boat... ZZZzzz...
Oh... and if humans are so intelligently designed... why are there like... um... encyclopedic volumes of human medical ailments from congenital anomalies to myriad diseases of every organ system... and up to 30% spontaneous abortive loss during the very basic act of reproduction... not to mention a heap o' ailments primarily due to our upright posture?
NEXT!
Loved Spin-oza's piece!
Reply | Report Abuse | Link to thisPlant's perceive light too. It's called phototrophism.
Thanks Muse. It seems our creationist-troll seems to be utterly speechless or... is plying thier sullied wares... St. Elsewhere:-)
Reply | Report Abuse | Link to thisCheers to all who humbly accept our place in this stunning, inexorably evolving Cosmos, free of the blinders and delusions of stale religious dogma!
Spin-oza (comment 10),
Reply | Report Abuse | Link to thisRe: "NOW... Mr. Creationist... tell us again about how the sequence of events in the bible-creation-myths work... the (Olive) Garden... Adam n' his rib spawin' all Homonids... Noah's lil' boat... ZZZzzz.."
Since that narrative will obviously put you to sleep, allow me to try another approach:
Re: "...[T]he evolution of the human eye has been nicely worked out by Zoologist Dan-Erik Nilsson."
Please check out comment 6.