vision is called the ability to interpret our environment with light rays reaching the eye. Vision or sense of sight is a major sensory capabilities of man and many animals. To be able need the proper functioning of the visual system is composed of the eye, optic nerve and various brain structures.
The eye is the gateway for entering the light stimuli are transformed into electrical impulses through a specialized cells of the retina are the rods and cones.
now know with certainty that not all animals have the ability to distinguish colors, there are many who have a magnificent view, but all I see in black and white or in shades of gray there are others who differ only bulk of objects, others, can only perceive changes in light intensity, and finally, those who are totally blind. All of them, however, have managed to overcome these deficiencies during its evolution, successfully adapted to the conditions and changes in their environment without much difficulty. The best proof of this is that have survived over millions of years, until today
· mites: their sense of vision in general is very poor. Most of them are completely blind, no eyes, however, many respond to changes in light intensity due to certain areas that are thin and transparent on the surface dorsal de su cuerpo.
· Las abejas: en 1914 el investigador alemán Karl von Frisch, pudo comprobar que las abejas tienen un sentido de color especialmente desarrollado, siendo capaces de diferenciar tres colores complementarios, entre varias intensidades de gris: el amarillo, el verde-azul y el azul. El rojo no pueden verlo y fácilmente lo confunden con el negro; en cambio pueden ver el ultravioleta. Por eso es que son atraídas por las flores rojas porque en las flores casi nunca se presenta sólo el color rojo; las amapolas, por ejemplo, que atraen de manera especial a estos insectos, tienen también algo de azul en su composición, pero lo más importante es que reflejan los rayos ultravioleta, perfectamente visible to bees. They may also differentiate the yellow, orange and green. Can distinguish colors but its sensitivity starts in the range of ultraviolet and goes to orange. Some of them can not distinguish red from gray.
· Fish: color vision depends on the depth or the turbulence of the waters, the optical media is clearer (coral reefs, lakes and rivers clean) in which all colors are equally abundant or more " dark "and blue (deep water) or reddish-brown (muddy ponds and streams), are in this group, from monochromatic vision (color blind) and (dichromatic) in fish in troubled waters (trichromatic) on coral reef fish (tetracrómatas) in fish from fresh water crystal clear waters which collect in the ultraviolet.
· Frogs and Toads: Vision is the dominant sense in most amphibians can see colors and have a good view, something important for animals that depend on the quick flight to avoid its many predators.
· Starfish: see only light and darkness, through the "eye cups" filled with light-sensitive cells in the tip of each arm, you can see in many directions, waving their arms and can project their glasses eye out to see better. Other animals with eye glasses are marine worms, some mollusks such as limpets, crustaceans, copepods and larvae of marine animals.
· The eyes of the animals that live in the ocean depths have developed a single class of photoreceptors (rods), capable of responding to stimuli of low light intensity, lack of color vision.
· Turtles: have little hearing, are virtually silent, but to compensate, have good sense of smell, sharp vision and color perception almost as good as humans.
· Lizards: have movable eyelids and good vision during the day, although some can not distinguish colors.
· Snakes: most have relatively poor eyesight, with the exception of the arboreal snake of tropical forests that have excellent binocular vision to find prey among the branches of trees where the smell would be impossible to follow.
· Pigeons: can perceive more colors than a human because they have up to five different types of cones.
· Butterflies: have four different types of cones. You can see a wide range of colors.
· mantis shrimp: has at least 12 kinds of cells sensitive to color and is probably the animal that perceives color.
· Squirrels: have only two types of photosensitive cells, so we see fewer colors, also has only two different types of cones.
· Raccoons and salamanders: have not only have cones and rods in their eyes, so one can not perceive color, but only changes in light intensity: the world is a world of shadows where shadows less dark than under light and less dark, less light. His world is in grayscale.
· Octopuses: not see colors, plus rods, has only one type cone (need to distinguish at least two colors).
· The animals whose body shows opaque colors, dark and inconspicuous , as in most mammals except humans, generally have a very limited colors or see but not perceive the same so that human.
· nocturnal animals that live underground like cururo possess some cones in their retinas, their way of life mainly nocturnal reveals a world in black and white. Birds (owls), amphibians (toads), reptiles (gekos) and rodents.
· animals bearing bright bold colors and, in some or all structures in your body, like many birds, reptiles, fish, insects and some spiders are able to distinguish colors.
· Herbivores: is determined to be able to distinguish colors. Recent research shows that cattle, sheep and goats have dichromatic vision, with cone of maximum sensitivity to light yellow-green and blue-purple. Most of these species are a full range of two colors, usually the entire spectrum, from green to blue:
· Cattle widespread belief that the bull is furious with the red cape is not true; what is striking is the movement itself.
· The horse: some studies showed that it could distinguish red and blue gray, but that did not distinguish green from gray. In another study found that most horses could differentiate the gray red, blue, yellow and green, but a horse could not distinguish between yellow and green.
· Dogs: for many years it was believed that dogs see in black and white, or who were blind to color. However, scientific studies have determined that it is not. And in fact, capture the tones similar to humans, although a decrease in the ranges of red and green. Can distinguish blue from yellow, red or green, but can not distinguish red from green. They can see colors, but not as much as men because we only have two different types of cones. Some studies also claim that the dogs see the world brighter and less detail than we are, approximately six times less
· Cats: for many years, scientists believed that cats had only a monochrome vision, because they did not teach to distinguish some colors from other (rewarding them with food.) However, trained cats come long enough to distinguish some colors, and have been found cones sensitive to green and blue, not red. Giving time can distinguish red and blue and white together, but are probably much like the green, yellow and white, and red they see it as a dark gray
More information: http://www . monografias.com/trabajos48/vision-animales/vision-animales2.shtml
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