Despite the fact that the majority of the population is afraid of the frightening look of tarantulas and does not tolerate these insects in every possible way, the popularity of breeding tarantulas at home is growing rapidly every year.
Over time, tarantula spiders become obedient pets and an exotic addition to the home collection. The huge demand for tarantulas is due to the simplicity of the content and the charming external data of the arthropod.
To date, science knows more than forty thousand species of arachnids. Very often, novice breeders rush to buy and acquire too complex representatives.
Before purchasing such a pet, it is necessary to study its features, characteristics, as well as the level of toxicity of the poison. Indeed, by mistake of the owner, the insect can be doomed to death.
How many eyes do most spider species have?
The sight of spiders that weave webs and wait for prey is much weaker than that of species that prefer active hunting. The main task of the organ of vision is to notice the approach of prey or danger. 4 pairs of eyes are considered classic for a spider.
Find out what the peacock spider, tarantula spider, Apulian tarantula, goliath spider, Brazilian wandering spider and black widow look like and where they live.
There are so many of them, for example, in the spider-cross. However, this is not the limit: the maximum number of pairs encountered is 6.
This number for a particular species depends on the habitat, hunting method and type of prey. The eye must be large enough for the species to function normally. So, the cave six-eyed crab spider is almost blind, and the horse is equipped with 8 organs of vision, located in 3 rows. According to the observations of scientists-arachnologists, the jumping spider sees well and can even distinguish colors.
Did you know? Spider-cross
- night Hunter. Therefore, the work of his organs of vision is similar to the sensitivity of a camera that takes pictures in night mode using infrared radiation. Only the insect is guided by polarized light for this.
Individual individuals
The spider-cross 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 the night mode. But if the camera perceives infrared light, then the spider's eyes are polarized radiation.
A jumping spider with 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 light-sensitive layers. During the hunt, they help him to accurately aim. Arachnology has even established that horses can distinguish colors.
In the photo: Araneus diadematus
Cave spiders are practically blind and rely on other senses as much as possible. Orb-web spiders have the smallest eyes. For example, Araneus diadematus simply senses movement when a victim falls into its net.
Types and structure of the eyes
The organs of vision in a spider are not the same. Their number, quality of perception of the picture and what functions they perform depend on the species of arachnid. Most spiders have simple peepers. But some species are additionally equipped with complex faceted ones. In total, there are 3 groups of spider visual organs:
- main pair (medial);
- additional side (side);
- faceted.
The front pair is larger, its task is to track the prey, so to speak, to show the prey in close-up. The muscles that are responsible for the movement of the retina are attached to the main pair. This pair consists of an eye capsule, inside which is a layer of light-sensitive cells, and behind it is a layer of nerve cells that form an image and transmit it to the ganglion (plexus of nerve cells).
Anterior medial eye in sagittal section: 1 - oculomotor muscles; 2 - retina; 3 - lens. The lateral organs of vision are smaller, they cannot turn, since they do not have attached muscles, but at the same time they are equipped with a kind of mirrors that can reflect sunlight. Side eye function - increasing the viewing angle to monitor the situation around the insect. The same organs can fix the light source, determine the distance to the object, notice prey or danger.
Did you know? It is the compound eyes that are responsible for color perception in insects.
Not all types of spiders have faceted ones. It is believed that these rudiments left the ancestors of spiders - chelicerates, which had a faceted structure of the eyes. 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 light-sensitive cells. This creates "blind spots" in the places of attachment of the optic nerve, but due to the large number of organs, this deficiency does not create inconvenience.
Associations
Looking at the photos of amazing creatures, you get the feeling that they came from other planets. Their eyes differ in functionality and size.
With the help of modern cameras, you can see the color up close, as well as the location of the eyes on the body. Someone in one row, and someone in three, or even four.
By the way, on our website you can find out what is the largest spider in the world.
The science that studies these mysterious and slightly intimidating creatures is called arachnology. They are studied by courageous people, since most of the inhabitants of cities and towns are afraid and have a negative attitude towards arachnid creatures. For some, it is not the spider itself that causes overwhelming fear, but even its image. They are widely represented in culture, and their images are found on the vases of the Sumerian kingdom and on the walls of the tombs of Ancient Egypt. The editors of the site ask all people who are not indifferent to spiders to write a comment about this article. How much do you like or dislike the eyes of spiders and do you find them unpleasant and scary? And below we will post some more beautiful photos of spider eyes.
That's all! But for those who are not enough, on our Zen channel we continue to publish photos of spider eyes.
What is the power of their sight
The ability to distinguish between the strength and direction of light allows the spider to track the direction of movement of prey. This is especially important for those who weave webs.
Important! The movement of objects is recorded with lateral eyes, then the spider turns to the target and can see 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's;
- the ability to see in close-up;
- spiders see objects close to them better than those far away at a distance of more than 10 cm;
- the ability to see in the ultraviolet spectrum;
- the ability to perceive polarized light;
- the ability to track 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.
Features of arachnid vision
The various species groups of this class have adapted well. For many, it is not the eyes that play the primary role, but tactile sensations. On the surface of the body, they have areas with increased sensitivity.There are especially many tactile hairs on the articulated paws, which are responsible for movement, and on the pedipalps (leg tentacles).
Many arachnids weave trapping webs. By the smallest vibrations of the threads, they learn about the prey they have come across. In this case, visual perception is less important. Species leading a nomadic lifestyle and hunting without cobwebs have more developed vision. To move around unfamiliar terrain, they must be able to distinguish between the surrounding reality.
However, their visual system also cannot be compared with the "optics" of developed higher insects. The eyes of a scorpion also do not differ in the complexity of the device, or in the peculiarities of color rendering. It is believed that representatives of this suborder see even worse than spiders and are able to distinguish their own kind only from a distance of several centimeters.
Poisonous or not crusader
The poison is toxic to invertebrates and vertebrates. Has an effect on the body of rats, mice, humans, rabbits. Sheep, horses, guinea pigs, dogs are resistant to poison. For insects, invertebrates, the attack of the crusader is fatal. In animals, there is a temporary deterioration in well-being, external irritation.
The crusader is not dangerous to humans. At the sight of people, the spider tries to hide unnoticed. However, in the event of a threat to its own life, it can bite. 2 small spots remain on the body. Initially, there is pain, burning. The next day suppuration occurs. In people with weakened immunity, children, after a spider bite, their general well-being worsens. Weakness, nausea, headache, dizziness, abdominal discomfort appear. The condition returns to normal after a few days.
Which spider builds underwater nests?
Silver spider builds underwater nests
The silver spider builds underwater nests. It is very common on the territory of the Russian Federation, it exists under water. As a rule, a spider creates several domes - these are nests filled with oxygen.
- Silver domes are summer.
- They can also be designed for hiding, mating, or eating.
Also, the spider makes a separate nest for collecting sperm, laying eggs and there is a "room" for molting.
Tarantula cocoon
For several months, the female weaves a cocoon for future offspring. At first, it looks shapeless like a piece of cobweb. However, after a while you can see a fully formed sphere.
In no case should the female be disturbed, since at this moment she is very aggressive and can rush, despite her belonging to a peace-loving species. The incubation period can last from three weeks to several months, depending on the breed of arthropod.
Food
The main diet consists of insects of various sizes. Flies, wasps, hornets, grasshoppers, locusts, caterpillars, butterflies come across in the spider's trapping nets. Snakes, frogs, toads, and mice get entangled in large strong cobwebs.
Spider cross
The internal digestive system is absent, food liquefaction occurs outside. The spider bites the victim, injects poison that paralyzes the muscles, immobilizes the prey. The spider launches saliva into the insect's body, envelops it in cobwebs, waits for several minutes. In 5-20 minutes, the insides of the prey turn into a liquid mass, which the predator sucks in.
Reproduction
The mating season begins at the end of summer. The female waits for the male on her web, feels his approach by the oscillation of the nets. After fertilization, it weaves a cocoon, lays up to 250 eggs inside. Carries with it, then leaves it in a secluded place. In this state, young growth overwinters. Spiders are born at the end of April.
The growing up period lasts several months. During this time, the nymphs molt about 5 times, increase in size, acquire a characteristic color. By the end of summer they become sexually mature. Caterpillars and aphids act as feed for young animals.
How adult spiders hibernate - they hide in the crevices of the walls, utility rooms, forest floor, tree hollows. They are active with an increase in air temperature in spring.
The basics of the basics
The body of the tarantula is divided into two parts - the cephalothorax and abdomen. The cephalothorax contains the spider's main central control organ - the brain. Spiders-wolves, not without reason, are called one of the most intelligent arachnids, because their brain volume occupies about 30% of the entire space of the cephalothorax!
Four pairs of legs covered with fine hairs are also attached to it. They also cover the abdomen of the tarantula. This is his secret weapon.
In case of a threat, the tarantula spider rises on its hind legs, and with its front legs quickly and quickly brushes off these villi, which, falling on the enemy, say, on a person, cause him an unpleasant itch, like from glass wool. But this is not as dangerous as it might seem, the irritation goes away rather quickly.
If I don't eat it, I'll bite it!
The structure of the tarantula also has one more feature - huge chelicerae. These are the "jaws" of the spider. With them, he captures prey and injects poison.
The digestive system of a tarantula consists of two stomachs, as well as an intestine and a digestive gland - the liver.
The circulatory system in a tarantula is a tube with a branched network of vessels extending from it, through which a clear liquid flows - the so-called hemolymph.
The tarantula breathes with the help of special holes in the exoskeleton - spiracles. Through them, air enters the spider's lungs, which also have an unusual device. They are also called pulmonary books, since one of the walls of each of the two lungs is folded like book pages.
Although the tarantula does not weave webs, it does have spider glands. With this web, he lines the mink, and the female weaves a cocoon for her eggs.
Scorpios: lifestyle
These arthropods are most often found in regions with tropical climates. Some species are diurnal, but the vast majority are still nocturnal hunters. They prefer to hide from the scorching heat and hide during this period under stones, snags and in other secluded places.
This is partly due to their imperfect vision. They can notice the danger only from close range, and they have better adapted to hunt at night. But this is not only because of the specific features of vision. It doesn't matter how many eyes a scorpion has - they do not play a decisive role in catching prey. It is believed that the main merit of accurate attacks is the sensitive sensors on their paws.
The circular stance of the legs gives the scorpion the ability to feel the smallest vibrations of the soil from all sides. By the speed of propagation of such signals (the near legs feel them earlier), it determines the exact location of the victim. The eyes play a secondary role in this. It is noticed that if you separate the scorpion and the victim with an obstacle in the form of a thin crevice, he will not be able to attack it even from close range. In this case, signals on the soil from the movement of prey to its sensitive legs do not reach.
Flickering characteristics
Fly eyes
There is an indicator of visual ability, which is associated with the flicker frequency of the image, that is, its lowest limit at which light is fixed as a constant source of illumination. It is called CFF - critical flicker-fusion frequency. Its value shows how quickly the animal's eyes are able to update the image and process visual information.
A person is able to catch a 60 Hz flicker frequency, i.e., an image refresh 60 times per second, which is adhered to when displaying visual information on a television screen. For mammals (dogs, cats), this critical value is 80 Hz, which is why they usually do not like watching TV.
The higher the blink rate value, the more biological benefits the animal has.Therefore, for insects in which this value reaches 250 Hz, this is manifested in the possibility of a faster reaction to danger. Indeed, for a person approaching "prey" with a newspaper in his hands with the intention of killing it, the movement seems to be fast, but the unique structure of the housefly's eye allows it to catch even instantaneous movements, as it were, in slow motion.
According to biologist K. Gili, such a high critical frequency of flickering in flies is due to their small size and rapid metabolism.
The above analysis of visual abilities makes it possible to understand that the world through the eyes of a fly looks like a complex system of a large number of pictures by analogy with small video cameras, each of which conveys information to the insect about a small part of the surrounding space. The assembled image allows flies to keep a visual "all-round defense" at a glance and react instantly to approaching enemies.
Where dwells
The species is distributed throughout Europe, some species are found in North America. Favorable conditions for existence are high humidity, high temperature, lack of direct sunlight. Ideal habitats are coniferous forest, swamps, forest edges, hedges. Less often they settle in meadows, fields, orchards, vegetable gardens, outbuildings, and residential buildings. In Russia, the CIS countries, there are about 30 types of crosses.
Once in a man's house, the spider chooses places away from noise and light. Occupies the corners at the top of the room, below the furniture. Weaves a web. It feeds on "domestic" insects - flies, cockroaches. To get rid of a spider with a cross on its back, it is necessary to remove its web, throw it out into the street, and poison the "living creatures".
