It is questionable whether anyone with good eyesight can even imagine their life without it. A visual guide through the world, these front sight organs are one of the most important, if not the most important on the human body. The amazing formation mechanisms of the eye enable animals to perceive their surroundings in the way best suited for them.
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
While evolution has led the human body to evolve different means of protection, these can be separated into three layers: the most outer layer is the skin eyelid that covers the eye and also waters it. The second layer is the membrane that surrounds the soft tissue of the eyeball. And the remaining layer is the cavity made of bone in which the eyeball resides. Such highly developed mechanisms are a clear indication that eyes should be well taken care of.
Scientists have not thus far managed to build a device that will be able to replace the eye, regardless of how simple the process of seeing may seem when looked at first. The initial stages of seeing are, in fact simple, and consist of light detection, but the sophisticated interactions between the eye and the brain follow after, and researchers do not yet understand how these work.
In favor of the claim that the eye is one of the most important sense organs in all organisms is the fact that there are more than 10 distinctive kinds of eyes present among various animal species. On top of that, it is believed that these evolved independently from each other. The fact that it is not just a few organisms that recognized the evolutionary importance of eyes, but ten different once, underlines the claim that eyes are of such great importance.
The type of sight animals and organisms possess is suited to their evolutionary needs. While some microorganisms possess eyes powerful enough only to distinguish between light and dark, some birds are even capable of seeing UV. Humans, for instance, have a moderately good ability to detect depth, color and direction, while the mantis shrimp's hyper-spectral vision is believed to be the most intricate system of color vision there is.
The human eye can easily be compared to a telescope, camera, microscope or other devices that use light focusing. Light first enters the iris, and is immediately focused onto a small patch of light-sensitive cells at the back. The cells transform the photons into neural signals. In order the change the quantity of light entering the eye, the iris changes size.
Things are relatively simple before the light reaches the rods and cones (the light sensitive cells) but afterwards become appreciably more complex and as yet no convincing explanation of how people actually see has been put forward by the scientific community. The eye is a fascinating instrument and more still remains to be known about it. This is one reason why everyone must take every precaution to keep his or hers healthy, imagine losing such a wonderful gift!
Eyes are believed by scientists to have evolved at about the same time as the first animals (during the Cambrian explosion) in one species and within a few million years had spread to most of the others. No other sense organ is more common among the animals, probably a measure of the eye's utility. With the eyes usefulness also comes it's vulnerability due to it being constructed of mostly soft tissue.
While evolution has led the human body to evolve different means of protection, these can be separated into three layers: the most outer layer is the skin eyelid that covers the eye and also waters it. The second layer is the membrane that surrounds the soft tissue of the eyeball. And the remaining layer is the cavity made of bone in which the eyeball resides. Such highly developed mechanisms are a clear indication that eyes should be well taken care of.
Scientists have not thus far managed to build a device that will be able to replace the eye, regardless of how simple the process of seeing may seem when looked at first. The initial stages of seeing are, in fact simple, and consist of light detection, but the sophisticated interactions between the eye and the brain follow after, and researchers do not yet understand how these work.
In favor of the claim that the eye is one of the most important sense organs in all organisms is the fact that there are more than 10 distinctive kinds of eyes present among various animal species. On top of that, it is believed that these evolved independently from each other. The fact that it is not just a few organisms that recognized the evolutionary importance of eyes, but ten different once, underlines the claim that eyes are of such great importance.
The type of sight animals and organisms possess is suited to their evolutionary needs. While some microorganisms possess eyes powerful enough only to distinguish between light and dark, some birds are even capable of seeing UV. Humans, for instance, have a moderately good ability to detect depth, color and direction, while the mantis shrimp's hyper-spectral vision is believed to be the most intricate system of color vision there is.
The human eye can easily be compared to a telescope, camera, microscope or other devices that use light focusing. Light first enters the iris, and is immediately focused onto a small patch of light-sensitive cells at the back. The cells transform the photons into neural signals. In order the change the quantity of light entering the eye, the iris changes size.
Things are relatively simple before the light reaches the rods and cones (the light sensitive cells) but afterwards become appreciably more complex and as yet no convincing explanation of how people actually see has been put forward by the scientific community. The eye is a fascinating instrument and more still remains to be known about it. This is one reason why everyone must take every precaution to keep his or hers healthy, imagine losing such a wonderful gift!
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