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This majestic bird has eyes that differ from our human type, human, rear portions the eagle eye being larger and flatter, providing the basis for much better visual acuity. The focusing point on the retina is known as the fovea, and where the human eye contains about 200,000 cones per mm, the eagle has five times as many, which inevitably leads to 1thier being capable of seeing objects or prey in a much more well defined basis, even at long distance. Eagles, like Owls are possessed of three eyelids, of which the bottom one is large, this being the reason for the odd fact of these birds always blinking upward instead of the usual downward motion.

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Crocodile tears are a figment of some sharp imagination, because these prehistoric monsters, have no tear ducts, and are thus unable to shed tears. Their eyes, though, do  produce secretions, which lay behind the third eyelid, also called a nictitating membrane, serving as both cleaner and lubricant. This membrane travels across the surface of crocodile eyes regularly, helping to inhibit the development bacteria, and because part of this membrane can be seen in the corner of these  eyes, when fully opened, the accompanying moisture can be mistaken for tears.


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There are few eyes anywhere on earth as striking as those among reptiles, where upper and lower eyelids have fused through evolution, so that a single large hole remains, through which the pupil of the eye can see. Chameleons, owners of these most impressive features, are able to roll, or even to rotate each eye independently of the other,  allowing it to view two separate objects from two directions at once, almost perfect visual acuity, with a 360 degree field, unique in the natural world.


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Do you know why snakes like the Python shown above always keep the eyes open? They do not have movable eyelids as most lizards do, which help them to lubricate and protect their eyes. This is why snakes always stare at prey. The eyes are protected by tough, immobile, transparent scales.  While snakes do not have very good eyesight, their sense of smell, the reason why their tongues are always so active, is the best in the animal world.  Some of snake species have a reddish brown ring around the left edge of their pupils, and even green, orange, gold, yellow or brown eyes.


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The incredible Tarsier is smallest known primate on earth, but has been gifted by nature with truly huge eyes compared to the rest of the body. These astounding eyes are so big that the tarsier cannot turn them around in the eye sockets,  so the little creatures have a special neck adaptation that allows them to rotate their heads a full 180 degrees. These mesmerizing eyes are the largest of all known land mammals, massive pupils providing night vision that is second to none, allowing the Tarsiers to be skilled night hunters.


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The Gecko is an interesting small lizard, which has enormous eyes for the size of the creature. Hunting for prey at night, as all nocturnal creatures do, the vertically slit pupils of these huge globe-like eyes come into their own, opening wide, and allowing maximum amounts of the poor light available to enter the eyes, helping achieve much clearer night vision. In daylight hours, however, when the Gecko is less active, those enormous pupils shrink down again to a tiny slit. These amazing  eyes are protected from dust and debris by  transparent membranes, kept  clean and moist by the regular use of the long sticky tongue as a wiper…


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Scallops are very strange creatures, from a visual point of view, having many eyes sited along both right and left valve mantle margins. Each eye is quite unique, working something like la reflecting telescope, in that it bounces incoming light onto animage-forming retina, after which this crude image forms, on light-sensitive cells found right in the middle of these peculiar eyes, which, as a matter of interest, can always be regenerated, making the loss of any one unimportant.


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The frog has some of the strangest characteristics with regard to eyes. When this creature shoots out their long tongues, their eyes shut completely, so they cannot see the targeted prey, yet they still catch it. They are also capable of allowing their eyes to sink back through openings in the skull, when swallowing prey, helping to ease the process of getting the food down the throat. This is why Frogs always to blink whilst feeding.


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These truly astonishing insects are amazing creatures, each having large, multi-faceted compound eyes, almost all of the head of this beast taken up by the two eyes. Each eye has as many as 30,000 individual lenses known as ommatidia, separate, light-sensitive organs, the enormous number giving these incredible insects full 360 degree perfect fields of vision


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The assassin fly, often mistakenly seen as a bee, lives happily throughout the grasslands of the world, with excellent vision, that helps the fly properly judge distance, and speed of anything moving ahead of it. On seeing potential food sources, it will close in, looking to investigate further. These flies have enormous heads, and huge compound eyes, each of which contains several thousand separate lenses, providing vision so sharp that it is especially useful in sighting small prey insects from afar.

These are truly amazing sights to see, the visual organs of other creatures, in a range so diverse it takes your breath away. Nature is genuinely astonishing, because whatever the problems that life presents to her offspring, she finds a way to help them live better lives.


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All images used with permission

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  • Emma

    I love that the snakes eyes look like marbles :)

  • http://www.primarysourcebook.com/ Auron Renius

    The Tarsier looks a bit wasted lol