Spiders - a special class of living creatures, which was named after a girl from Greek mythology. In the myth of the weaver named Arahna, who dared to challenge Athena to a contest in skill, it is said that the goddess won, not recognizing the efforts of a simple girl. From resentment and frustration, Arahna wanted to hang herself. However, Athena, she was turned into a spider, tirelessly weaving its web.
And now let's take a closer look at some of the characteristics of these arthropods. What features of the structure and behavior of the spider krestovik help these living creatures to survive?
The special life of spiders
The cross spider (photo confirms) is a typical representative of its class. To the squad arachnids also include mites and scorpions. More than 300,000 species of this class live in tropical and mixed forests of our planet. To find out what features of the structure and behavior of the spider cross there, you need to be very careful observer. Most often, the "weaver" itself is invisible to us. But its web is quite noticeable!
The behavior of the spider-krestovik due to its way of life and habitat. Forests, parks, gardens and various green spaces - all this can be home to representatives of this species. In human dwellings, one can also often find araneus diadematus.
Description of the appearance of the spider krestovik
The bodies of all spiders are similar:
- small head,
- large abdomen egg-shaped,
- 8 legs.
According to the pattern on the surface of the back, similar to a cross, this species got its name. The so-called eyes (8 pairs of pieces) are located in front of the spider's cephalothorax. The krestovik’s mouth consists of several “parts”: a pair of claw-jaws with poisonous glands on the bases, and a pair of tweezers (chelicera) —the organs of touch.
The structural features of the spider spider allow it to survive, attack and feed with the help of its powerful jaws. On the legs are comb claws, with which the “forest weaver” creates its sticky network. Web warts are at the bottom of the abdomen. Despite having so many eyes, the spider family sees very badly. The main helper for survival is the sense of touch with the help of sensitive feet.
The way to feed the cross
The builder and the hunter, the krestovik spider eats everything that falls into its traps. These can be gadflies and flies, mosquitoes or various midges and small insects. All representatives of this species are predators, including the cross. The photo helps to see the process of catching insects in the sticky web of the web. Grasping the prey by the pelvis, with its jaws-hooks, the spider bites through it, injecting paralyzing poison into the wound of the victim. At the same time, digestive juice enters the body, softening the insides of the fly.
With his insatiable appetite, this insect hunter is able to suck more than a dozen flies at a time. If there are too many victims, the behavioral peculiarities of the spider-spider prompt him to wrap the captives in a cocoon and leave him “for later”. Stocks are suspended from the trap on the strands. Spiders are not adapted to eating solid food. But they can suck the softened entrails of insects. For such an extraintestinal feeding method, the arachnids do not need stomachs.
How spiders multiply
Only at the end of the summer period do the octopus forest dwellers reach puberty. Observing what features of the structure and behavior of the cross-spider contribute to the reproduction of this species, biologists have found that females are more than twice as large as males. Living alone, only by the autumn the spider goes to look for a “lady”. Attaching his thread to the trap of the female and tugging at it, he draws the attention of the female in this very way. The pairing that occurs is the last event in the life of the male - the “lady” eats him after the fertilization process. The instinct of saturation, nothing personal!
Eggs the female spider lays in the autumn months, wrapping the clutch in a dense filament cocoon. With such silk protection, future offspring will easily survive any frosts. Hanging in secluded places, in the crevices of tree bark, these cocoons will open next spring. Little spiders, after wintering, will come out to build their own traps.
What makes a spider weave a web
Without its graceful trap, this predator would not be a spider. Let's look at what features of the structure and behavior of the spider-spider make it weave for life and nutrition.
- Hunger - the root cause of all the actions of representatives of this type. To have food, you need to find a place suitable for the trap.
- When the arthropod is determined with the territory, the next instinct turns on - the spider composition begins to stand out.
- Each action triggers follow-on signals of the required continuation. Everything is arranged simply and clearly.
The skills of the spider in weaving a fishing net can be innate, built into the genetic code, or acquired, depending on the living environment. However, the general scheme of the web always has a lot of the same parts. Ideally woven spiral coils are fixed along the radii of the network with equal angles. In this case, the center of gravity always coincides with the center of the arachnoid grid.
About spiders, web and man
Remembering the signs and scientific research, one can find out what features of the behavior and structure of the spider-cross used by humanity for the treatment of various diseases.
- By applying a fresh web shot to a small wound, you can stop the blood.
- It is believed that the decoration with the image of the forest octopod brings monetary luck.
- European medieval healers claimed that wearing a pendant in the form of a spider on the chest would save diseases.
- If the “handsome” sits in the very center of his trap and does not crawl out, then it will rain.
- If the spiders weave fresh webs, then it is to sunny weather.
In conclusion about the benefits of the arachnid order
If it were not for this family, mankind could suffer great losses every year from
yield losses. Spiders play virtually the leading role in the fight against pests. Over a season, more than 200 kg of possible carriers of various infectious diseases are destroyed on a hectare of forest territory by these gluttons.
Spiders, as is known, mainly feed on small insects, but there is one species - Kepling Bagir (lat. Bagheera kiplingi), whose diet consists solely of plant food. This spider lives in Central America, it is known as almost the only vegetarian spider.
This spider feeds on buds and acacia leaves and has no natural protection against predators. By the way, some ants feed on the same plants and zealously protect their food sources, therefore spiders sometimes have to fight for food. In a fraudulent way, they steal leaves one by one when there are no ants nearby.
Some species of spiders prey exclusively on food. using theft other spiders. They secretly sneak up on the networks of unsuspecting brethren and steal the captured prey. By the way, often after they captured someone else's lunch, they do not disdain kill the masterwhose territory has been sneaked. One crime is worse than another!
Of course, spiders do not have gills, like fish, and they are not able to breathe under water, but some of them manage to easy to dive and stay there long enough. Water spider (lat. Argyroneta aquatica), which lives in Europe, is able to stay under water for more than a day. He uses a special bag made from his own silk, in which he keeps air bubbles and thus breathes.
Ultimately, air reserves are running out. After that, the spider pops up and again replenishes air reserves.
All spiders shed old skin, that is, from time to time molt. Most often, molting occurs in youth, but in adulthood, spiders also shed the upper layer of skin. A few weeks before the molt begins spiders begin behave strangely. They may stop eating or they may have bald patches (for example, tarantulas).
The molting process is usually complex and takes a lot of time. A cocktail of hormones makes you separate. spider skinIn exchange, a new skin is formed, however, it is not necessarily in that order.
In order to confuse enemies, spiders make special snares from their netsthat remind them of themselves. Some of these tricks have the same dimensions as the spider itself, others are much larger. This is probably done in order to intimidate the enemy.
Researchers have occasionally noticed that some spiders are shaking their webs with deceptions to give the impression that snag is real live spider. Surprisingly, the trick works, and spiders have less problems with predators.
Horse spiders were sent into space to check whether they were able to build networks in low gravity conditions. Spider, named Nefertiti (pictured), has adapted to the new conditions and was even able to catch flies. She could not jump on her victim, but learned to sneak approach prey. She managed to develop this skill in just a couple of days!
Nefertiti died of natural causes after her space mission was completed and she returned to Earth.
Regardless of size, all spiders weave complex nets. It turns out that this ability takes a lot of energy and requires a sufficiently developed and large brain. Studies have shown that the smaller the spider in size, the larger its brain (in proportions to the rest of the body).
Some spiders have a brain that is so large that all other organs are forced fit in his legs. In other words, these spiders become just walking brains.
Incredible web strength
If someone actually had the talents of Spider-Man, he, like the hero of a comic book, could easily jump from one building to another, and his cobweb would easily withstand the weight of his body. In reality spider silk is stronger than steel! For example, if you take a sheet of silk thick 2.5 centimeters, he could stop the jet fighter.
Spiderwebs are very beautiful, however, spiders have a lot of workto put them in order. They usually use silk, but sometimes they can also use other materials, such as decorating cobwebs. bags of eggs.
There are several theories as to why spiders do this: probably to make networks stronger or to attract partners. In one study, it turned out that spiders decorated their webs after damage, which confirms the version that decorations help them strengthen their nets.
In 2011, residents of one of their Pakistani districts were amazed when, on waking in the morning, they found that the trees were completely covered in cobwebs. Millions of spiders climbed trees to escape floods, each of which wove its own web. Deveriya became like ghosts.
Spiders amazing abilities
Spiders are among the most diverse, widespread and successful predators in the animal kingdom, partly due to their universal abilities that are exclusively at their disposal. Their paws can pass on any surface, in the canines lies a deadly poison, and in their body is an adhesive substance, more durable than steel. You might think what else these animals need to survive, but there are spiders who have much more interesting "tricks" hidden in their pockets.
1. Web shooters.
Almost all spiders create their thread from the spinning organs at the end of the abdomen, but they need to be able to touch something in order to start producing it. But the predator of the genus Scytodes is nothing. In the so-called "spitting" spider, there are additional spinning glands in the mouth. Slowly approaching unsuspecting insects, the spider expels a stream of silk soaked in its own poison.
2. Submarine "boats".
Water spiders are the only ones that live completely under water. Their hairy abdomen, covered with a fatty substance, is capable of creating a balloon around itself. Spiders only occasionally rise to the surface to renew its stock. Their nest is made of cobwebs attached to plants, and is also filled with air inside. It is there that predators consume prey and raise offspring.
3. Deadly attractiveness.
The whimsical spider called Mastophorea uses a difference from any other arachnid group, and has found an excellent use for its abilities. He hides a tight, round glue ball at the end of a single long fishing line ... full of bait. Each species of spider emits a pheromone that attracts individuals of a different type of moth, searching for females. Intoxicated by the smell, the insect immediately falls into a trap from which it cannot get out.
4. False advertising.
Many garden spiders build a web with a distinctive pattern of thick silk in the center, the purpose of which has long been discussed. Now we know that this special silk reflects ultraviolet rays, creating patterns similar to those that use flowers to attract pollinators.
5. Portable mini-web.
Ogre spiders are known for hanging upside down, holding an unusual small and at the same time strong network between the front legs, which is used to “manually” catch insects. This silk is special, not sticky, but so nappy that it immediately entangles the paws of the victims like a velcro. This allows the spider to catch large and powerful insects with only a small amount of silk.
6. Numerical advantage.
Most spiders persistently lead a solitary lifestyle, treating even individuals of their own species as simply the edible invader of their territory. Other social creatures who are able to share their home with thousands of similar spiders. Some of these are the spiders of the genus Theridion, who patiently hang upside down in huge groups. When some large insect passes under their web, dozens of spiders descend simultaneously and in the blink of an eye wrap their prey in silk.
7. Disguise as an ant.
There are more than a hundred species of spiders, most of the family of horse spiders, which remotely resemble ants. Yes, this is the spider in the photo above. These animals use such a disguise to hunt insects that are not afraid of ants or to protect themselves from predators feeding on spiders. Others prefer in this "form" to hunt the ants themselves, like a wolf in sheep's clothing.
Recently it turned out that a new species of very small spiders are able to travel "climbing a hang-glider" for many kilometers. A special type of silk called “cobweb” is very easily lifted by the wind, forming it into a triangular parachute, which can remain on the fly for many weeks. It even allows spiders to create their colonies on individual islands.
9. Fake spiders.
Most spiders end up on their own web, hanging along with uneaten prey. No one could have imagined that another spider could use all this. Some varieties wrap old food in silk. By giving them the same shape and color as themselves, they thereby create a series of “false” spiders, among which they can hide. All of this can attract flying predators, such as dragonflies or small birds, who will dare to eat a dead spider.
10. Masking in the style of "bird droppings".
Celaenia excavata is not the only spider that disguises itself as bird excrement, but it is he who turns out to be the most convincing of all. Not only is the spider's body colored exactly like droppings (even stains, like undigested seeds), it also does its best to look as convincing as possible. The “splashes” woven from his own silk are direct evidence of this. This disguise is probably one of the best, because the appearance makes it unappetizing for spider-feeding animals and very attractive for various insects.
Could it be possible that such abilities would appear in spiders absolutely by chance, without the intervention of reason? Or is targeted fishing visible, a wise device that cannot appear as a result of the chaotic movement of life?