How many eyes does a spider have, what do their visual organs look like and where are their eyes?

The number of eyes on spiders varies from zero to eight. While most species of spiders have 8 eyes, some spiders, such as Sinopoda Scurion, have no eyes at all!

Arachnophobia, the fear of arachnids, especially spiders, is one of the most common animal phobias. In fact, a study claims that almost 3.5% to 6% of the world's population is afraid of spiders. However, what makes these multi-legged crawling creatures so scary? Is it the fact that they appear and disappear almost instantly? They can be there one second and disappear in the blink of an eye. Poof! Or do movies depict spiders? Or maybe it's the number of beady eyes looking at you? Speaking of eyes...how many eyes should you worry about?

Types and structure of eyes

Spiders' visual organs are not the same. Their quantity, the quality of image perception and what functions they perform depend on the type of arachnid. Most spiders have simple peepers. But some species are additionally equipped with complex facets. In total, there are 3 groups of spider visual organs:

main pair (medial);
additional lateral (side);
faceted.

The front pair is larger; its task is to track prey, so to speak, to show prey close-up. The muscles responsible for the movement of the retina are attached to the main pair. This pair consists of an eye capsule, inside which there is a layer of light-sensitive cells, and behind it is a layer of nerve cells that form the image and transmit it to the ganglion (plexus of nerve cells).

Anterior medial eye on a sagittal section: 1 - extraocular muscles; 2 - retina; 3 - lens. The lateral organs of vision are smaller; they cannot rotate because they do not have attached muscles, but they are equipped with a kind of mirrors that can reflect sunlight. The function of the side eyes is to increase the viewing angle to monitor the situation around the insect. These same organs can detect a light source, determine the distance to an object, and notice prey or danger.

Danger to humans

This type of arthropod belongs to the category of weakly poisonous arachnids and is not at all prone to attacking warm-blooded animals or people. When danger is detected, the wolf spider quickly turns over with its belly up and stops showing signs of life. In this relatively uncomfortable position for arthropods, without movement, the spider can remain for a long time, until the threat has completely passed.

There are known cases where a sharp and sudden attack on a wolf spider caused aggression in it and provoked the arthropod to bite, which is not capable of directly threatening human life, but can cause pain, redness of the skin and moderate swelling. In this case, it is recommended to apply an ice pack to the bite site, as well as take any antihistamine.

So why do most spiders have so many eyes?

Both human and spider eyes are the result of slow development that helps them survive in different environments. One of the reasons our human eyes are different from spiders is that our bodies and brains are also built differently. For example, spiders do not have necks. So they can't turn their heads to look at things like we do. Having extra eyes is one of the ways spiders see more around them and this helps them quickly spot prey or a potential predator.

Human eyes and spider eyes also do different jobs. Our two eyes are very complex and are good at many tasks at once, while spiders have different types of eyes that do different jobs.

For example, the large central eyes of jumping spiders are best suited for observing figures, but the simple side eyes serve an important function for observing predators.

So a two-eyed spider or an eight-eyed man cannot exist. But the two eyes that we have, and the eight eyes that most spiders have, are perfect for helping us live the way we do.

Tarantula spider: a charming representative of the exotic world

Habitat

However, the venom of tarantulas is not considered fatal, at least so far there have been no recorded cases of human death from a spider bite. People going to the hospital are caused by the body’s reaction to spider venom.

You may experience fever, cramps, or severe allergies. In this case, symptomatic remedies will be quite sufficient.

The spider uses venom only to paralyze its victim, but not to poison it. The tarantula kills completely mechanically, striking with sharp chelicerae. However, the reaction to poison in small animals or children can be so strong that without timely “quenching” of the symptoms it can lead to death.

Interesting! When in danger, the tarantula can emit a hissing sound, which is sometimes clearly audible within a radius of 15 meters.

Tarantulas come in many colors, from deep brown and black and white to bright blue, red and black and orange. From the front, if you look closely, you can see the eyes and mouthparts

Appearance

The body structure of different species of tarantulas is approximately the same

Attention is drawn to the relatively large fluffy abdomen, which turns into a massive body-head

The paws are long, strong and also fluffy. Tarantulas come in many colors, from deep brown and black and white to bright blue, red and black and orange.

From the front, if you look closely, you can see the eyes and mouthparts.

Despite having eight eyes, the tarantula spider has very poor eyesight. Therefore, he uses his body villi as a guide, which he uses to pick up the slightest vibrations in the air.

Interesting! At certain periods, the tarantula may change its orientation somewhat in terms of lifestyle. If it was a burrower as a larva, then, having become an adult, the spider can spend a lot of time on the surface of the earth.

Despite having eight eyes, tarantulas have very poor eyesight. Therefore, as a guide, they use their villi on the body, which capture the slightest vibrations in the air.

It is correct to count the age of spiders not in years, but in molts. First, a small spider is born - a nymph, which may not need food at all. After a couple of molts, the nymph becomes a larva or young spider. After the next shedding of its “skin,” the tarantula is considered an adult

With each such change of “skin,” the tarantula significantly increases in size, up to one and a half times, and its coloring and body proportions may also change, as evidenced by the photo and description of the tarantula spider.

Interesting! Females live much longer than males. This is explained by the fact that upon reaching puberty, males stop molting, but in females this process continues for a very long time. You can significantly extend the life of a spider with the help of thoughtful feeding and temperature conditions.

The tarantula spider by nature is an omnivorous predator; it eats everything that moves and is smaller in size. This includes insects, small reptiles and rodents, and, of course, birds

Tarantulas by nature are omnivorous predators; they eat everything that moves and is smaller than them. This includes insects, small reptiles and rodents, and, of course, birds.

In summer you can catch grasshoppers, caterpillars and flies for your predator

It is important that they are free of pesticides. The spider will enjoy hunting “naked” baby mice or adult mice. At the poultry market, locusts, frogs, crickets, mealworms, zofobus, and small lizards are sold as food. You can start breeding marbled cockroaches and feed them to the tarantula. Even if these insects accidentally scatter around the house, they will not live long, since apartment conditions are not suitable for them. The water in the drinking bowl must be changed as it becomes dirty.

And the remains of the eaten “prey” - the web mixed with the shell of the victim - must be removed immediately, since ticks can grow there. They are not dangerous for a healthy tarantula, but during molting they can cause irreparable harm to it.

Interesting! A spider can go without food for two years. At the same time, he will behave actively; such fasting is something normal for him.

After a ritual dance, indicating to the partners that they belong to the same species, mating occurs. During this process, the male transfers seminal fluid into the female, which he previously placed on a specially woven web, where the act of love takes place

Visual system

In the process of evolution, different types of arachnids have developed a special vision structure. Hunting techniques and lifestyle depend on how many eyes the animal has.

Spiders that hunt by weaving webs have poor eyesight. More active hunters see much better. Basically, visual elements are presented in four pairs, arranged in 2 rows. The need for a large number of eyes is explained by the animal’s lifestyle. Arachnids have access to a 360-degree view.

However, in nature there are varieties that have 12 eyes, but there are also those who make do with one pair of visual elements.

However, these individuals also fully exist, because in nature every little detail is thought out.

Key facts

About 99% of spiders have eight eyes. Some have six, four or two.
Several species have vestigial eyes or no eyes at all.
Spiders have two types of eyes. A large pair of primary eyes recognize patterns. The secondary eyes help the spider track and measure distance.
The number and location of a spider's eyes helps an arachnologist identify the species of spider.

What kind of eyes do spiders have?

Most representatives of the huge family have 4 pairs of visual organs. Why a spider needs 8 eyes is explained by their lifestyle. Almost all types of arachnids are predators, some hunt while sitting in their burrows, others wait in the web, and others actively search for prey, exploring the surroundings. Such a number of pairs of eyes in a spider provides it with a 360-degree horizon.

Interesting!
The main organ connecting the animal with the outside world is the legs. On their lower part there are villi, which are responsible for the sense of smell and touch. The arthropod senses the slightest vibration in the air, gusts of wind, or the approach of prey.

There are rare species of arachnids that have 12 eyes. There are also owners of only 2 pairs.

Description and photo of the cross spider

The body size of females is from 20 to 40 mm, that of males is 10 mm. Consists of a round convex abdomen, cephalothorax. The body is covered with a durable shell, the legs are covered with villi. The crusader spider has 10 limbs, of which 4 pairs are walking legs. The front ones perform the functions of claws - they capture the prey and hold it while feeding. The paws are symmetrical to the size of the body. The structure does not differ from a typical arachnid. The cephalothorax is connected to the abdomen by a thin bridge.

How many eyes does a cross spider have - 8. Placed on the front of the head. 6 in the center, 2 large on the sides. This number of eyes provides a wide range of vision, but does not provide good vision.

The spider is myopic, sees everything in general terms - movement, shadow, silhouette. The organs of smell and touch help the cross to navigate in space. Located on the legs. Finding itself in an unfamiliar place, the spider carefully feels the space initially with its paws, and then moves.

What a crusader looks like depends on the species. The body structure is the same, but the color is different.

The meadow crossweed lives in places with humid air, warm climate, and dim light. Painted in brown, yellow, red tones. On the belly on the upper side there are white spots in the shape of a cross. Thanks to this identification mark, all species of araneus are called crosses. The meadow predator weaves a web on the grass and hunts small insects.
The forest cross differs from the garden and meadow in its darker color. The body is dark brown with white stripes. The characteristic white or brown sign of the cross is clearly visible on the abdomen. The paws are long. The largest cross in Russia. The size together with the leg span reaches 4 cm.
The Far Eastern cross is distinguished by its large size. Habitats: forest, field, meadow. The color is brown with different shades. The cross on the abdomen is white or yellowish. It weaves the largest web, which reaches 2 m in diameter. Even frogs, toads, and snakes can become entangled in strong webs.
An orange or yellow spider with a cross on its back is an ordinary crusader that lives in shady places in forests, fields, meadows, and gardens. Araneus angulatus is a rare species listed in the Red Book. Body size is about 18 mm.
The predator with a red cross on its back is a type of meadow cross. Bright spots scare away enemies, but do not mean that this representative of the genus is more poisonous.
A black spider with a white cross on its back is a crusader that lives near swamps, in the forest, in fields, and rarely approaches a person’s house. Outwardly it resembles a tegenaria.

Individuals

The cross spider looks at the world around it with eight eyes. He hunts at night, and therefore the work of his organs of vision resembles the work of a video camera operating in night mode. But if the camera perceives infrared light, then the spider's eyes perceive polarized radiation.

The jumping spider, which has eight eyes arranged in three rows, is able to determine the distance to an object. He measures the exact distance with his front main eyes. They consist of four photosensitive layers. When hunting, they help him aim accurately. Arachnologists have even established that horses can distinguish colors.

In the photo: Araneus diadematus

Cave spiders are practically blind and rely as much as possible on other senses. Orb-weaving spiders have the smallest eyes. For example, Araneus diadematus simply senses movement when prey gets caught in its web.

Why would a spider look like an ant?

By portraying ants, the spider ant wins in everything. They are no longer hunted by birds and wasps, which are afraid of small but aggressive insects. Their bites and the acid they throw at their enemies are painful. Therefore, predators try not to mess with these spiders, which are almost indistinguishable from ants.

These insects are the main object of hunting for jumping spiders. Camouflage allows the “werewolf” to easily approach his victim. Of course, it won’t attack in front of everyone, but out of the many insects scurrying around in the anthill, someone is sure to encounter a spider “on a narrow path” without witnesses. By the time he realizes the mistake, it will be too late. Spiders run faster and can jump quite far from an ambush.

The third advantage of camouflage is that spiders get “both a table and a house.” Unsuspecting ants let them into the anthill, where it is warm, dry, clean, and safe. Here the horses live in comfort, even setting up their family homes, where they raise their spiderlings. In a secluded corner of the anthill, the female makes a nest, lining it with cobwebs, then lays eggs. The hatched babies already look like the owners of the anthill, this is how nature instilled it in their genes.

Spiders - what are they: types

Researchers know about 42 thousand species of spiders. Spiders can be divided into three large suborders, which differ mainly in the structure of the jaws, or more precisely, in the position of the chelicerae relative to the longitudinal axis of the body.

Suborder Orthognatha

More often, representatives of this suborder are called migalomorphs. They are characterized by the presence of thick hairs, large sizes and a primitive structure of the jaws - the claw is directed downwards and grows only on the upper jaw. The respiratory system is represented by pulmonary sacs.

The majority of mygalomorphs live in warm climates. They make burrows underground.

Orthognatha includes:

tarantula spiders
funnel spiders
ctenizidae
digger spiders

Representative of the suborder Araneomorpha

Suborder Araneomorpha

Almost all other species of spiders known to naturalists belong to the large group Labidognatha or Araneomorpha. They differ in that both jaws are equipped with claws. The respiratory system is represented by the trachea.

Types of spiders that catch prey without a net:

crab spiders
jumping spiders
wolf spiders

Types of spiders using a trapping net:

linifid spiders
web spiders
funnel spiders, or house spiders
long-legged spiders
orb weaving spiders

Among the araneomorphic spiders, there are also those that are not capable of producing cribellum, the substance from which spiders produce strong web silk, and those that produce it.

Suborder Mesothelae

Lyphistiomorphic spiders are distinguished by the fact that the chelicerae are spread out to the side rather than pointing downwards. This position is considered more evolutionarily advanced. But this suborder is considered the most primitive; traces of it were found in Carboniferous deposits. Spiders have archaic pulmonary sacs and four pairs of arachnoid warts, which have not yet been moved to the end of the abdomen. They live in earthen burrows that are closed with a lid. Signal threads radiate from the minks. Although one species prefers caves, where it makes web tubes on the walls.

These include:

arthropod spiders
primitive arthrolycosid spiders
primitive arthromigalid spiders

Blue tarantula spider

General characteristics. External structure

The cross spider can be found in the forest, park, and on the window frames of village houses and cottages. Most of the time, the spider sits in the center of its trapping network of adhesive thread - cobweb.

The spider's body consists of two sections: a small elongated cephalothorax and a larger spherical abdomen. The abdomen is separated from the cephalothorax by a narrow constriction. Four pairs of walking legs are located on the sides of the cephalothorax. The body is covered with a light, durable and quite elastic chitinous cover.

The spider periodically moults, shedding its chitinous cover. At this time it is growing. At the anterior end of the cephalothorax there are four pairs of eyes, and below there is a pair of hook-shaped hard jaws - chelicerae. With them the spider grabs its prey.

There is a canal inside the chelicerae. Through the channel, poison from the poisonous glands located at their base enters the victim’s body. Next to the chelicerae there are short organs of touch, covered with sensitive hairs - the tentacles.

At the lower end of the abdomen there are three pairs of arachnoid warts that produce cobwebs - these are modified abdominal legs.

The liquid released from arachnoid warts instantly hardens in air and turns into a strong web thread. Different parts of arachnoid warts produce different types of webs. Spider threads vary in thickness, strength, and adhesiveness. The spider uses different types of web to build a trapping network: at its base there are stronger and non-sticky threads, and concentric threads are thinner and stickier. The spider uses webs to strengthen the walls of its shelters and to make cocoons for eggs.

Features of character and lifestyle

The male cross has dimensions in the range of 8-10 mm, females are larger - 15-25 mm. The insect has four pairs of eyes, each of which looks in a different direction and provides the spider with a fairly broad horizon. Despite this, cross-haired people see poorly, they are myopic and are able to distinguish only shadows, movement, and the outlines of objects. But they have a keen sense of smell and taste. The spider's body is covered with hairs that sensitively detect any vibration and vibration.

The common cross has eight legs, its abdomen is round in shape, and white or light brown spots in the shape of a cross are visible on it. Long thin legs end in three claws.

main pair (medial);
additional lateral (side);
faceted.

We invite you to find out how long turtles live at home

A large number of eyes allows the spider to see almost around itself. In addition to them, the spider has sensitive hairs on its legs, with which it “hears movement,” complementing the visual picture of the world.

Features of spider vision are:

number of organs;
each eye sees a separate picture, but for the spider it combines into one whole;
different structures of the main and additional organs.

So, knowing the spider’s habitat and its species, we can draw conclusions about how many eyes it has and how it can see. Without such information, our understanding of arachnids will be far from complete.

The amazing inhabitants of the planet have three main types of eyes:

Main pair. They are also called medial;
Lateral additional, so to speak, side;
Faceted

The main pair helps the pack track the victim. These eyes are the largest and located in front of the other visual organs. Inside the capsule of the medial eyes there is a layer of light-sensitive cells, and muscles are attached to the eyes themselves, whose task is to move the retina.

The lateral eyes are smaller than the main ones and are in a static state. They expand the viewing angle and fix the light source. They help to assess the situation around, as well as notice danger and prey.

Not all species have compound eyes, but they help spiders perceive colors. These organs, inherited from distant ancestors, are able to perceive and reflect light.

Spiders differ from other inhabitants of the planet in the number and location of their visual organs on the body.

Each optical organ sees a separate area, but for an animal the world is formed into a single picture.

They don't have to constantly turn their heads to see what's to the side or behind. The organs of vision differ in their structure, and each performs its own special function, helping the spider navigate the world around it.

At the lower end of the abdomen there are three pairs of arachnoid warts that produce cobwebs - these are modified abdominal legs.

The spider's digestive system consists of the mouth, pharynx, esophagus, stomach, and intestines (front, middle and back). In the midgut, long blind processes increase its volume and absorption surface.

Undigested residues are expelled through the anus. The spider cannot eat solid food. Having caught prey (some insect) with the help of a web, he kills it with poison and lets digestive juices into his body. Under their influence, the contents of the captured insect liquefy, and the spider sucks it up. All that remains of the victim is an empty chitinous shell. This method of digestion is called extraintestinal.

Circulatory system

The spider's circulatory system is not closed. The heart looks like a long tube located on the dorsal side of the abdomen.

Blood vessels extend from the heart.

In a spider, the body cavity is of a mixed nature - during development it arises from the connection of the primary and secondary body cavities. Hemolymph circulates in the body.

Respiratory system

The spider's respiratory organs are the lungs and trachea. The lungs, or pulmonary sacs, are located below, in the front of the abdomen. These lungs developed from the gills of the distant ancestors of spiders that lived in water.

The cross spider has two pairs of non-branching tracheas - long tubes that deliver oxygen to organs and tissues. They are located in the back of the abdomen.

Nervous system

The spider's nervous system consists of the cephalothoracic nerve ganglion and numerous nerves extending from it.

The excretory system is represented by two long tubes - Malpighian vessels. One end of the Malpighian vessels ends blindly in the body of the spider, the other opens into the hind intestine. Harmful waste products come out through the walls of the Malpighian vessels, which are then excreted. Water is absorbed in the intestines. In this way, spiders conserve water so they can live in dry places.

Sense organs and central nervous system

Spiders have a diverse nervous system structure. The organization of the latter corresponds to the ventral nerve chain, but there are certain nuances: the brain does not have a middle section (deutocerebrum). This is due to the simplified structure of the acron appendages, which are excited by this part of the brain in insects and crustaceans.

The protocerebrum is preserved , as well as the tritocerebrum, the posterior part that innervates the chelicerae. The nerve cells of the abdominal chain are concentrated and form a ganglion mass. However, in ticks, the ganglia fuse to form a ring near the esophagus.

Animals' sense organs are developed differently. For representatives of this class, the sense of touch is very important. A large number of hairs, called trichobothria, are scattered throughout the body. The greatest accumulation is observed on the pedipalps of the spider.

These hairs are movable, each is attached to a special hole in the skin and connects to sensitive cells that are located at the base. Each trichobothria reacts to the slightest vibrations, and the spider distinguishes the nature of the stimulus by the intensity of the latter. The role of support in the body of spiders is played by the chitinous cover.

Chemical feelings are felt through the lyre-shaped organs - these are openings in the skin that lead to sensitive cells. They are located throughout the animal's body.

Spiders' organs of vision are their eyes. The number of the latter ranges from 2 to 12. They are presented in the form of arcs and are located on the cephalothorax. Despite this, arachnids have poor eyesight. They can see clearly at a maximum distance of 30 cm, but for many species this is too much. Thus, scorpions distinguish objects at a distance of several centimeters.

Vision is very important for wandering species (jumping spider), with its help they monitor prey and distinguish between representatives of the opposite sex.

Nutrition

The main diet consists of insects of different sizes. The spider's trapping nets catch flies, wasps, hornets, grasshoppers, locusts, caterpillars, and butterflies. Snakes, frogs, toads, and mice get entangled in large, strong webs.

Cross spider

There is no internal digestive system, food liquefaction occurs externally. The spider bites the victim, injects poison that paralyzes the muscles and immobilizes the prey. The cross releases saliva into the insect’s body, envelops it in a web, and waits for several minutes. In 5-20 minutes, the insides of the prey turn into a liquid mass, which the predator sucks up.

Cow and horse

Many people will probably be surprised that cows cannot distinguish the color green. For them, the whole world is enclosed in either red or orange colors. But for cows, the pasture is a different color, not green.

For a horse, the world is black and white, but there are many more shades of gray in a horse’s vision than a person can distinguish. The horse's eyes perceive the world as two different halves, since the eyes on the face of this animal are located far from each other.

How many pairs of eyes does a spider have?

During evolutionary development, different species developed a special structure of vision and the number of eyes. Their number depends on the lifestyle and method of hunting of the arachnid. Animals that prefer to hunt using professionally woven spider webs have poor eyesight. Active hunters see better. Basically these are 4 pairs lined up in rows. Why a spider has 8 eyes is due to its lifestyle. All eight provide them with an excellent outlook at 3600.

In nature, there are species that have 12 eyes, and there are also those who get by with just one pair of visual organs. But one pair ensures their existence in the outside world. Everything in nature is thought out to the smallest detail.

Description and characteristics

The body of every arachnid creature includes two main parts.

The abdomen, on which there are special breathing holes and warts, through which individuals weave webs.
The cephalothorax is covered with a special shell made of chitin, which has 4 pairs of jointed legs. That is, the answer to the question of how many legs a spider has is 8. The number of eyes can reach a similar value.

Spider structure

Large spiders can reach a body size of up to 10 cm. The smallest individuals have dimensional characteristics of 0.4 cm (this is the smallest spider). The coloring features depend on the structure and structure of the scales and integument, so some individuals can be monochromatic, while others have a bright color.

Types and structure of eyes

main pair (medial);
additional lateral (side);
faceted.

Not all types of spiders have facets. It is believed that these rudiments were left to spiders by their ancestors - chelicerates, which had a faceted eye structure. Such organs are also capable of detecting and reflecting light. In the structure of the lateral auxiliary organs of perception, the layer of nerve cells is much closer to the light flux than the light-sensitive cells. This creates “blind spots” at the attachment points of the optic nerve, but due to the large number of organs, this deficiency does not create inconvenience.

Muscles of the eye

Around the outer surfaces of the eyeball are muscles that are connected to the eyelids. With their help, the eyes close and open. This system performs two functions:

moisturizing, that is, closing the eyelids during sleep prevents excessive drying of the eyes, thereby reducing the load;
protective, for example, if a strong wind is blowing outside, a person closes his eyes to prevent foreign particles from entering the mucous membrane.

Inside the orbit around the apple, muscles are concentrated that hold it, preventing it from falling out or in. The internal structures of the eyes also contain muscles, which are divided into two categories:

around the iris, which constricts or dilates the pupil, so that a person can adapt to exposure to bright light or being in the dark;
around the lens, allowing it to change shape to view objects near and far.

Where are the spider's eyes?

The most important pair of eyes is in front. Externally it differs from the others in size. The rest are on the sides on both sides. A photo of the spider's eyes is located below. You can examine them without a magnifying glass in large representatives of the family - tarantulas, tarantulas, goliaths, etc.

The main organs of vision are medial, located in front, conveying the overall picture. The remaining pairs are secondary, warning of the approach of a victim, a natural enemy.

On a note!
Some species have compound eyes. They are placed on the sides and are practically no different in appearance from the front ones.

How does a spider weave a web?

In the back of the spider's abdomen there are from 1 to 4 pairs of arachnoid glands (arachnoid warts), from which a thin thread of web stands out. This is a special secret, which nowadays many people call liquid silk. Coming out of the thin spinning tubes, it hardens in the air, and the resulting thread turns out to be so thin that it is quite difficult to see with the naked eye.

In order to weave a web, the spider spreads its spinning organs, and then waits for a light breeze so that the spun web catches on a nearby support. After this happens, he moves along the newly created bridge with his back down and begins to weave a radial thread.

When the base is created, the spider moves in a circle, weaving thin transverse threads into its “product”, which are quite sticky.

It is worth noting that spiders are quite economical creatures, so they absorb damaged or old webs, after which they reuse them.

And the web becomes old very quickly, since the spider weaves it almost every day.

Advantages

It's time to tell you what advantages spiders have with their visual organs and their structure.

Firstly, the number and structure of the eyes allows you to see a more detailed picture. It is even better than that of a human;
Secondly, with the help of the first pair they see a close-up;
Thirdly, they are shortsighted. They see objects that are beyond 10 cm worse than those that are close;
Fourth, they have the ability to see ultraviolet and perceive polarized light;
Fifthly, they accurately determine the distance to an object, see everything that is happening around them and, with the help of their eyes, easily navigate the grass.

Meaning of "camera film"

Focusing results in focusing the image on the retina, which is a multi-layered light-sensitive tissue covering the back of the eyeball. The retina contains approximately 130 million photoreceptors (for comparison, modern digital cameras can be cited, in which there are no more than 10,000,000 such sensory elements). Such a huge number of photoreceptors is due to the fact that they are located extremely densely - approximately 400,000 per 1 mm².

It would not be out of place here to cite the words of microbiologist Alan L. Gillen, who speaks in his book “The Body by Design” about the retina of the eye as a masterpiece of engineering design. He believes that the retina is the most amazing element of the eye, comparable to photographic film. The light-sensitive retina, located on the back of the eyeball, is much thinner than cellophane (its thickness is no more than 0.2 mm) and much more sensitive than any human-made photographic film. The cells of this unique layer are capable of processing up to 10 billion photons, while the most sensitive camera can process only a few thousand. But what’s even more surprising is that the human eye can detect a few photons even in the dark:

In total, the retina consists of 10 layers of photoreceptor cells, 6 layers of which are layers of light-sensitive cells. 2 types of photoreceptors have a special shape, which is why they are called cones and rods. Rods are extremely sensitive to light and provide the eye with black-and-white perception and night vision. Cones, in turn, are not so sensitive to light, but are able to distinguish colors - optimal operation of the cones is observed in the daytime.

Thanks to the work of photoreceptors, light rays are transformed into complexes of electrical impulses and sent to the brain at incredibly high speed, and these impulses themselves travel over a million nerve fibers in a fraction of a second.

The communication of photoreceptor cells in the retina is very complex. Cones and rods are not directly connected to the brain. Having received the signal, they redirect it to bipolar cells, and they redirect the signals they have already processed to ganglion cells, more than a million axons (neurites through which nerve impulses are transmitted) which form a single optic nerve, through which data enters the brain:

Two layers of interneurons, before visual data is sent to the brain, facilitate parallel processing of this information by six layers of perception located in the retina. This is necessary so that images are recognized as quickly as possible.

The power of vision

The ability to distinguish between the strength and direction of light allows the spider to track the direction of movement of its prey. This is especially important for those who weave webs.

Important! The movement of objects is recorded by the side eyes, then the spider turns to the target and can examine it in close-up with the help of the main ones. Without lateral additional organs of vision, he will not be able to hunt.

The advantages of spider vision can also be called the following:

better picture detail than a person;
ability to see close-up;
Spiders see objects close to them better than objects at a distance of more than 10 cm;
ability to see in the ultraviolet spectrum;
ability to perceive polarized light;
the ability to follow prey in any direction around you;
eyes help to move quickly in the grass;
the spider does not miss when jumping for prey, which means it can very accurately determine the distance.

The main eyes of spiders are able to see even what a person cannot distinguish. In particular, the sensitivity of these creatures to ultraviolet radiation has been proven. Almost 6 thousand species of jumping spiders have this ability, which, unlike other representatives of arachnids, prefer not to wait for prey in an ambush, but, on the contrary, to actively hunt it.

Tennet spiders, spiders that catch prey using webs, have poor eyesight. Their vision allows them to record the movement of relatively large objects (moths, flies) and respond to changes in the direction and intensity of light.

Top 5 largest spiders in the world

Let's look at the five that were officially recognized as the largest.

5th place. Purple tarantula

One of the huge spiders is the purple tarantula, which lives mainly in the forests of Colombia. It is in this place that its subspecies are most numerous in the world. The largest spider of this genus, which has been officially registered, has a length of 34.5 cm, but the average specimen reaches a length of 26 cm. It is worth noting that this large spider is not dangerous to humans, only its bite can cause an allergic reaction. Distinctive appearance features:

only its abdomen is covered with thick hairs, and its paws are long and drooping;
females are dark blue, purple and black in color;
males are yellow-green in color.

4th place. Camel spider

This type of insect got its name because it has several humps on its head, which is why it has been compared to camels. These spiders prefer to feed on lizards, rodents and small birds. While hunting, it is capable of reaching speeds of 16 km/h. And its size reaches 30 cm including limbs. It is yellow-brown in color and has tentacles on its head that also serve as limbs. Thanks to four eyes, this species is excellent at distinguishing moving objects. Its chelicerae are very sharp and can easily cut the skin and hair of their prey. If a camel spider bites a person, the area may become inflamed because there is an infection on the chelicerae. Habitat is Asia, North and South America, Africa and some European countries.

3rd place. Salmon pink tarantula

Even though this species is considered the largest spider, some people keep it as a pet. The pink tarantula reaches a size of 30 cm and in the wild it feeds on small snakes, lizards and birds. The tarantula has lightning speed, so the victim has no chance of survival. Habitat is Brazil. Distinctive external features:

the head and chest are covered with a shield, which depicts a design in the form of a 10-pointed black star, while the color itself is salmon;
at the base of the limbs, which are adjacent to the body, the color is pink, and then it turns into dark gray;
the belly and legs are heavily covered with hairs.

2nd place. Giant Crab Spider

One of the largest and arthropod insects in the world is the crab spider, or it is also called the huntsman spider. Its size reaches 30 cm and even more. It got its name due to its external resemblance to a crab and its ability to move. Its body is gray or brown, sometimes the color may contain spots or red splashes. The main feature of this giant is that it quickly kills its prey and feeds on insects and small invertebrates. When the victim is in his paws, he immediately injects his poison, which affects the victim's nerve cells. The venom contains a neurotoxin that can cause pain and swelling of the limbs. It attacks a person only in self-defense, but people still try to avoid it. It lives in Australia and Japan.

How does an animal see?

Spiders have blurry vision. Arthropods see no further than 25 centimeters.

The image appears as shadows or silhouettes. Spiders' visual organs perfectly detect moving objects and infrared radiation that comes from prey or an enemy.

First, the image is captured by the side pair. The image is then focused with the front eyes. The picture becomes clearer, which allows the animal to determine who is in front of it - a living creature or an inanimate object.

Thus, the advantages of a spider’s vision include better vision of nearby objects than at a distance of more than 10 cm. Unlike humans, arthropods have good detailed images, see close-up, and perceive ultraviolet rays.

Spiders are also able to observe the prey around them in any direction and perceive polarized light. The special structure of the visual organs allows animals to move quickly, accurately calculate distances and not miss when attacking prey.

So, to understand how many eyes a spider has, you need to familiarize yourself with the evolution of arachnids. The number of visual organs depends on the habitat, type and hunting characteristics of the animal.

Reproduction

The mating season begins at the end of summer. The female waits for the male on her web and senses his approach by the vibrations of the web. After fertilization, it spins a cocoon and lays up to 250 eggs inside. He carries it with him and then leaves it in a secluded place. The young animals spend the winter in this state. Spiders are born at the end of April.

The maturation period lasts several months. During this time, the nymphs molt about 5 times, increase in size, and acquire a characteristic color. By the end of summer they become sexually mature. Caterpillars and aphids serve as food for the young.

How adult spiders overwinter - they hide in cracks in walls, utility rooms, forest litter, tree hollows. They become active as air temperatures rise in spring.

Neighborhood with people and interesting facts

Some species of spiders live in close proximity to people. They live where there is sufficient food. Arthropods often eat insects. Typically the following types are found at home:

Haymaker. Its body size reaches 12 mm, but its paws can be 5 times longer. It mainly weaves webs on windows, which is why it is also called window weaving.
Tramp. They appear randomly in residential buildings. This species does not spin webs, but hunts on the move.
Brownie. Body length varies from 6 to 12 mm. Yellow color. They create a funnel-shaped web.

Spiders usually appear when there is a high level of humidity in the house or when there are a large number of different insects. In this case, they multiply quickly and can take over the entire house.

Among the interesting facts about arthropods are the following:

There is a subspecies in the arachnid family, individuals of which are called phrynes. They are not able to weave webs and have large legs designed for hunting.
Spiders do not have a skeleton. They only have an outer hard shell, so they can't get too big. Otherwise, the arachnid would have died under its own weight.
The web is several tens of times stronger than steel.
All types of spiders make a round web, and only the gladiator makes a square one.

Many people are terrified of spiders. But in fact, there are no serious reasons for this, especially in Russian latitudes. Arachnids are considered the most unusual animals that live on Earth. They received such fame due to the features given by nature.

Medium poisonous spiders

The bite of such arthropods is not fatal, but can cause trouble in the form of swelling of the limbs and a painful bite site. These types include:

banana;
tarantulas;
spider sak;
wasp spider

The bites of these animals cause local irritation. With a very large dose of poison, swelling of the limb is possible.

Banana

Large arboreal orb-weaving spiders that spin the largest webs. They have several names:

banana spider;
giant tree spider;
golden weaver.

Large tree orb-weaving spiders
Body length 1-4 cm. Paw span 12 cm. Poison is not fatal to humans. A spider bite causes a local allergic reaction: burning, blistering, redness of the bite site. Symptoms disappear within 24 hours.

Tarantulas

They belong to the wolf spider family. The most famous are two species: the South Russian and Apulian tarantula. The common name for the South Russian tarantula is Mizgir spider. Large arthropods that do not weave trapping nets. They are nocturnal, attacking small invertebrates and other spiders. During the day they hide in vertical holes with a diameter of 1-1.5 cm and a depth of up to 0.6 m. The animals have a gray protective color. The abdomen is covered with bristles. Paws of medium length.

Tarantulas

Distributed in the southern dry steppes of the Eurasian continent. Tarantulas are especially poisonous in the spring after hibernation, before they have had time to waste the poison. But you have to try hard to get a bite from this arthropod: first remove it from the hole, and then grab it with your bare hand. In defense, the tarantula is capable of a vertical jump, but at the first opportunity it will try to hide.

Spider sak

The second name is yellow heyracantium. Originally an inhabitant of the southern regions. But the abnormal heat led to the fact that the arthropod began to be found in central Russia. The spread is facilitated by the sak's unhealthy addiction to the smell of oil. It often gets between the pipes of the car's propulsion system. The ventilation holes are clogged with their cobwebs.

Spider sak

The animal is not large: 0.7-1.5 cm. The paw span reaches 2.5 cm. The color is yellow-brown. It has impressive chelicerae with very long spines. This is a device for active night hunting. You can see what the sak looks like in the photo of the spider below.

Saka venom causes soft tissue necrosis. Other signs of poisoning may include nausea, headache, and high fever. The bite site becomes inflamed.

Argiope

She's a wasp spider. Belongs to the family of orb-weaving spiders. The wasp got its name from the characteristic coloring of its abdomen. In terms of the number of species, it is second only to jumping spiders and linifids. The range of Argiope is limited to 52°N.

Argiope

Hunting is passive. At dusk it weaves round trapping nets. Feeds on flying insects. The bite is painful. May cause local irritation.

Bottom line

The science that studies these mysterious and slightly terrifying creatures is called arachnology. Brave people study them, since most residents of cities and towns are afraid and have a negative attitude towards arachnid creatures. For some, it is not even the spider itself that causes irresistible fear, but even its image. They are widely represented in culture, and their images are found on vases of the Sumerian kingdom and on the walls of the tombs of Ancient Egypt.

The editors of TheBiggest.ru website ask all people who care about spiders to write a comment about this article. How much do you like or dislike spider eyes and do you find them unpleasant and scary? And below we will post some more beautiful photos of spider eyes.

Sources

https://ZaychikPipus.ru/nasekomye/domashnie-pauki-foto.html
https://AgroCompany-kazan.ru/drugoe/skolko-glaz-u-pauka-foto.html
https://beards-growth.ru/organy-zrenija-u-paukobraznyh/
https://agrovetspb.ru/nasekomye/glaza-pauka-skol-ko-par-gde-nahodyatsya-i-zachem-tak-mnogo.html
https://kursi-floristiki.ru/pauki/glaza-pauka.html
https://heaclub.ru/pauki-vidy-stroenie-tela-razmnozhenie-skolko-u-pauka-nog-glaz-kak-pletet-pautinu-skolko-zhivet-nasekomoe-ili-net-yadovitye-i-neyadovitye- pauki-spisok-s-nazvaniyami
https://dr-dez.ru/muhi/skolko-glaz-u-paukoobraznyh.html
https://tripchik.ru/kleshchi/skolko-glaz-u-pauka.html
https://lorises.ru/nasekomye/skolko-glaz-u-pauka-vikipediya.html
https://apest.ru/pauki/o-paukah/skolko-glaz-u-pauka/
https://MyTigers.ru/opasnye/skolko-u-pauka-glaz-foto.html
https://parazitdoma.ru/drugie-parazity/skolko-glaz-u-pauka
https://thebiggest.ru/lyudi-i-zhivotnye/glaza-paukov.html
https://100zaitsev.ru/chlenistonogie/glaza-pauka-kartinki.html
https://bier-loga.ru/nasekomye/kakie-glaza-u-paukov.html

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Easy spider drawing

If you don't have a goal to draw a spider in pencil, with shadows and fine realistic details, then you probably want an easy and beautiful drawing of a cartoon spider. It can be drawn by children or used on a postcard.

It's very simple - two ovals. The bottom one is the spider's head, and the top one is the stomach. Yes, the spider has a very big belly. Draw the spider's eyes and mouth.

Even in a small drawing we must indicate that the legs of the spider consist of links. Give them a form.

The shape of the legs is ready, now give them volume by repeating each line of the legs almost parallel.

Add a thread of cobweb on top, you can change the facial expression, change it to a smiling one.

Behavior

The jumping spider leads an active daytime lifestyle. He is able to expand his limbs against a background of changing blood pressure (internal hydraulic system).

With this in mind, there is no doubt about whether spiders are jumping spiders. They are able to do this over long distances, which significantly exceed the size of their own body.

. Horses also hold their bodies on horizontal glossy surfaces (glass). This is possible thanks to the small hairs and claws located on the paws.

When fleeing, jumping spiders often turn around, assessing the distance to the one who is pursuing them. It is usually not difficult to hide from an enemy, since their limbs are well developed.

Thanks to its powerful limbs, the arachnid not only successfully runs, but also jumps over considerable distances.

The jumping spider is found in such areas:

forests attract him with trees, any of which he can make his home;
mountains or steep cliffs are also interesting for him - there are cracks for his shelter;
fields attract him with tall grass or branches of bushes;
a person’s home can also become his home, since there is always a cozy sunny place for him there.

Jumping spiders are loners. They are most active during the day, and at night they look for some hidden place. To spend the night, the horse weaves a cradle from a web, lays down in it and rests there until the morning. With the advent of the first rays of sunlight, the horse awakens.

If it is not satisfied with weather conditions, the spider may decide not to leave its shelter for several days.

After waiting out the bad weather and seeing noticeable improvements in weather conditions, the horse leaves its cradle, warms up in the sun for a while, and then goes hunting.

Some species of jumping hoppers imitate ants. Mimicry (resemblance) is expressed not only in imitating the shape of the body, but they also repeat their movements. Thanks to this, horses are saved from road wasps that actively hunt them.

Purchasing Tips

The jumping spider is considered one of the most intelligent representatives of arthropods, due to the size of its brain. It is quite difficult to purchase such a spider in our country, but it is quite possible from lovers of exotic arthropods who breed them at home. The average cost of an adult varies depending on the species, but most often does not exceed a couple of thousand rubles .

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