Animals

What you wanted to know for years: this is how animals see

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The insects (arthropods) They can have up to three types of visual receptors, or also a mixture of several of them, such as:

1st dermal receptors: Although they are not cells dedicated to vision, some species have parts of their body that are photosensitive.

2nd Ocelos: Also called "simple eyes", since they are composed of a single receiving unit, or "omatidia." Most insects have these ocelli, either isolated or in small groups.

3rd compound eyes: Flying insects, which need greater visual resolution, have what is called "compound eyes", that are formed by multiple ocelli or receiving units (omatidia) (reaching 30,000 found in some species of dragonflies). Each omatide is formed by a lens, forming the surface face of each what is called a "facet", a transparent crystalline cone, photosensitive cells distributed radially around the rabdoma, which acts as a waveguide to diffuse the signal, forming an inverted image in the photosensitive retinular cells, and pigment cells that separate each receptor from the rest.

Thus, we see that the images that form in the brain of the insect with compound eyes are formed by a mosaic of tiny individual images that combine to generate an image formed by small "points", in a way, it resembles a digital image, in which each pixel is the image captured by a specific omatide.

While these compound eyes are superior to ours in some respects, we can confirm that in general insects look worse than us. In fact, returning to the simile of digital images, we see that insects see better or worse depending on the number of omatidia present in their eye, and as a general rule, this number is not high enough to homogenize the image quality to the that we get

According to studies, we can know that a bee sees about 60 times worse than us, that is, an object that we could discriminate at 60 meters, a bee can only discriminate at one meter. Part of the problem is also that compound eyes are unable to focus.

But not everything was going to be disadvantages: The compound eyes give the insect an extraordinary peripheral vision, thanks to the disposition of the omatidia, which in insects with better vision are usually arranged in a semi-sphere manner.

Most insects, the images that are formed in the insect's brain with compound eyes are formed by a mosaic of tiny individual images that combine to generate an image formed by small "points".

They have two kinds of pigments, which allows them to perceive some shades of colors. Insect pigment receptors are largely more displaced towards the ultraviolet of humans, which allows them to see this radiation perfectly. One of these pigments absorbs blue and ultraviolet and the other absorbs green and yellow. This means that they are not able to differentiate pure colors from others that are a mixture, more or less like the colorblind ones however with frequencies shifted towards ultraviolet. Also, they can't see pure red too well.

Some insects such as the bee, the bumblebee, or the dragonfly have three types of pigmentary receptors, so they can differentiate colors 360 nm (ultraviolet), 440 nm (blue-violet), and 588 nm (yellow-green-red) within their visual spectrum, which means they can distinguish any color or combination in a range from ultraviolet to yellow-red (without reaching pure red).

If you look, we can see that the bulbs or fluorescent tubes that are used to get the attention of insects are always blue-violet, since it is the color that they can best perceive. We can perform the experiment with a red light, and we can see that insects are not attracted to it.

Arthropods (Arthropoda, from the Greek ἄρθρον, árthron, "articulation" and πούς, poús, "pie") constitute the most numerous and diverse edge of the animal kingdom (Animalia). This term also includes invertebrate animals with an external skeleton and articulated appendages, among others, among which we could cite some examples such as: insects, arachnids, crustaceans and myriapods.

In some articles, text, images or videos will be added as we see fit, for a better illustration of them.

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How dogs see

Although it is commonly thought that dogs do not see colors, the latest evidence shows that this is false. Dogs, most likely distinguish blue and red colors. Also the yellows and browns. But they confuse greens and carmines since their vision is mainly dichromatic. Or so we think. Another interesting aspect due to the anatomy of your eye is different from what we see in humans. This influences the visual field, depth perception, visual acuity or movement perception.. For example, dogs need to blink less times than humans due to a thicker "tear gel." That for not having the Tapetum lucidum, a special layer that increases the ability to see in darkness. Probably, the perception of depth is compensated by the brain, as are the colors, to some extent, so that their vision is perhaps not so different from what we know.

How cats see

As with dogs, cats are also able to distinguish certain colors. In general, their vision is very similar to that of dogs. For example, their visual acuity is much lower than that of humans. These animals distinguish at six meters what we twenty-five. But they look much better in the dark thanks to that reflective layer that compensates for the lack of light. Cats, in addition, have a vertical pupil that allows them to better regulate the entry of light. In order to keep their eyes always in shape, as night hunters they are, cats have a nictitating membrane that protects the eye from foreign bodies.

How the birds see

Well, the first thing is to know that not all birds look the same. There is a very wide range of visual ability. In general, all birds look pretty good. Quite better than humans, in fact. The vision is one of its most important capacities because it depends on lots of vital aspects in its day to day, including hunting or refuge search. Thus they are able to "zoom" and focus objects unthinkably for any primate, focusing specific points at will. But even more impressive, probably, is another characteristic issue of birds: they are able to see ultraviolet light. Thus we have verified it with various experiments. Although we do not know how this will be represented in your brain, the truth is that birds can see colors that we do not even imagine.

How do insects see

Many arthropods possess an extraordinary sense of vision characterized by a compound eye. A compound eye consists of a lot of small, fixed eyes that, in combination, form a fragmented image. This is impressive if we consider that these animals do not have a large brain to process images, like the previous ones. Consequently, flies and other insects perceive a visual picture that seems to go in slow motion with a low rate of images per second. In addition, they are also able to perceive the ultraviolet range, which is essential for their daily lives. His eyes are efficient enough to give him an incredible advantage. And if not tell the most widespread taxon across the planet.

How fish see

This is also difficult to describe, because if the birds have different capacities depending on the species, the fish are even more complex in this regard. In general the anatomy of the fish usually confer spectacular depth of field, as well as a great peripheral vision, necessary adaptation to eyes located on the sides of the head. His perception of color varies a lot, although it is not especially good. Almost all are adapted to see any color other than blue, predominantly in the seabed. In addition, many have a great night vision capability with special adaptations or ultraviolet light reception.

How sharks see

Unlike most fish (specifically actinopterigios), sharks do not see colors. Neither do they need it. Sharks, like very old animals that they are, take advantage of the rest of your senses like electroreception or an incredible nose for hunting. It is only when they are in the middle distance when they use their vision. A clear and concise vision, quite similar to ours, we believe, but adapted to focus underwater. In fact, a shark looks very blurry if there is no water involved.

How rats see

A curious case is this mammal that has two tiny eyes on its sides. Unlike other animals, rats have a deep field of vision but a poor ability at close range, where they see everything blurred. They cannot distinguish all colors, seeing only the green and blue, mainly. In addition, as they have their eyes on their sides they have a limited binocular capacity. This means that rodents need to move their heads from side to side to correctly perceive depth in an operation called parallax. In addition, the eyes of rats can move independently and are capable of perceiving ultraviolet. Although they don't see colors very well, what they do perceive is the brightness of things.

How snakes see

Due to their long history on our planet, snakes also show all kinds of eye adaptations. In general, their vision is not very different from that of any other vertebrate except for a couple of extraordinary details. First, instead of eyelids they have eye scales that renew with the skin. And the most impressive thing is its ability to see practically as good daytime as night thanks to its thermal vision, as if it were a military camera. With it, practically no prey goes unnoticed at night.

Spider or ant?

The development of the application was born from research on a kind ofspider thathe achieved asingular mimicry with a kind of ant.

In fact, he did it so well that in order not to confuse them it is necessary to study them very closely.

"The scientistsset offnfrom the hypothesis that some species had developed more than others to adapt their visibility to prey or predators", they explain from the Information and Scientific News Service (SINC).

Spiders go unnoticed by their predators, which interested the experts, who later wanted to apply the software to other species, conducting experiments on bees and birds.

"The tool can be used to determine the visual accuracy of the species and will be especially useful for studying processes in which the detection of objects and their identification is important, such as exhibitions, camouflages and mimicry", explain their creators.

The next goal of scientists is to continue improving and expanding the information extracted to have an increasingly accurate idea of ​​how animals see the world.

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