Report on the topic Arachnids 7th grade message

Humanity is experiencing a panicky fear of arthropods. This is partly correct, because some of them are poisonous. The fear of spiders is called arachnophobia. It appeared in ancient times, when people lived in caves and often suffered from attacks by poisonous insects. But the planet is home to many harmless and amazing creatures. There are a huge number of interesting facts about arachnids that are worth getting acquainted with.

№1

The fact that there is a spider within 1 meter of you is a myth. However, there are still a lot of them. Scientists have identified more than 48,000 different species, which are distributed throughout the world, with the exception of Antarctica.

They are found in different parts of the planet, from deserts and jungles to swamps. They are also found in the mountains. For example, Euophrys omnisuperstes (Himalayan jumping spider) lives at an altitude of 6,700 meters above sea level. It was discovered on the slopes of Mount Everest.

A large number of tarantulas have been found in the Andes (one of the longest mountain systems).

Lifestyle and nutrition of spiders

In pictures, spiders are often depicted with a scary fanged mouth, but in fact, the spider’s feeding is structured differently and does not involve bites. As soon as the victim falls into the net, the spider recognizes this by the vibration of the web threads, approaches the prey and injects a poisonous secretion into it, which makes the body soft. After this, the spider sucks it up. That is, food softening occurs not in the same way as in the body of other animals - in the stomach, with the help of gastric juice - but externally. And the role of gastric juice here is played by a poisonous secretion. This principle of nutrition is called extraintestinal.

Almost all spiders are predators. And they feed mainly on their closest relatives - insects. The only “vegetarian” of all the spider diversity is the tropical spider Bagheera Kipling - he feeds on plants. But, according to scientists, during drought, when the spider cannot find fresh food, it does not disdain insects.

Large tarantula spiders can also eat more serious prey: small birds (hence the name), fish, rodents and other small animals. These spiders have teeth

The answer to the question of where spiders live is very simple: everywhere. Mostly on land, but there are also those who love a humid environment. They prefer warmth - but recently individuals have been found that can survive in the cold of Antarctica. The main condition for their life is the availability of food. Spiders are very voracious. And they can eat more than their weight in a day.

Some spiders make nests and burrows for themselves and their offspring, others do not have a permanent place, and lay their eggs in special cocoons, which are also woven from webs.

In nature, spiders have a difficult life, so they rarely live longer than a year. Birds feed on them, they suffer from cold and lack of food, from chemicals used to treat fields and forests. This is why spiders often settle in houses - there the only danger for them is humans, and encounters with them can be avoided in dark corners, pantries, basements and attics. Moreover, the spider almost always sleeps during the day and comes out to hunt at night, when the inhabitants of the house are sleeping.

At home, spiders live much longer. There are known cases where a tarantula spider lived at home for 30 years.

№4

Many have heard that the female karakurt (belongs to the species of black widows) eats her male after mating. However, this does not always happen. Sometimes the male manages to escape, sometimes the female does not show aggression if she is well-fed. But with the so-called “red widow”, also known as Bishop’s widow (also a type of black widow), the situation is different. After mating, the male offers to eat himself, trying to get into his partner’s mouth. If she refuses, he will put himself in her mouth until she eats him.

Unusual spiders

Spiders are distinguished by their enormous diversity, among which there are truly amazing species.

The biggest spider

The largest spider in the world is the Giant Huntsman Spider . He, of course, does not look like cartoon characters, where the size of a spider is often comparable to a cat, but is significantly larger than its fellows in size.

Its body reaches 5 centimeters in length. And the limb span is 30 centimeters. The Hunter does not live in our latitudes; he prefers warmer regions: Asia, Africa, Australia, South America. But it’s still useful to know that he may well bite a person (in defense). But without consequences, except for pain at the site of the bite.

In the Guinness Book of Records, another spider is named the largest - the Goliath tarantula . The span of its paws reaches 28 cm. It lives only in the tropics and is completely harmless to humans, although you cannot tell by its appearance.

The most beautiful spider

Many people believe that a spider cannot be beautiful in principle. However, there are several varieties of spiders that are at least colorful and unusual.

For example, Peacock spider . It lives in Australia and actually resembles a peacock not only in its unusual colors, but also in its habits. It is painted in all the colors of the rainbow and, like the peacock, it courts the female, fluffing its scales and performing a special dance.

Spider that lifts your spirits

On the Hawaiian Islands there lives a spider, of which the locals are very proud. This is the Smiling Spider . It got its name for the interesting coloring of its abdomen: two eyes and a wide red smile on a yellow background.

This spider is just a baby, no more than half a centimeter in length, but the islanders of Maui consider it their mascot and print its image on souvenirs.

Smart spider

Despite the fact that it is impossible to train spiders, these animals cannot be called completely stupid. This is especially true for the spider Porsha .

It belongs to the type of spider that does not weave webs, but hunts its prey (these are also representatives of arachnids) on the ground, jumping on it.

The spider demonstrates its intelligence during the hunt: it chooses the best option for attacking the victim: it can simply jump on it, or it can descend from above on a spider’s web. Or he can pretend that he has fallen into someone else’s web - and, when the potential victim becomes interested in him, suddenly jump.

The Porsche spider is very tiny (up to 10 mm), but with cunning it manages to defeat much larger spiders.

The most terrible spider

The Brazilian wandering spider is included in the Guinness Book of Records as the most poisonous spider in the world.

As can be understood from the name, this spider lives in South America and does not have a permanent place - it wanders. It is quite large (including paws reaches 15 cm) and furry. For the animals it hunts - and these can be insects and small rodents - its poison is fatal. It is also extremely dangerous for humans, as it destroys the functioning of the nervous system. Scientists have come up with an antidote, but it needs to be administered very quickly.

№13

Karakurts (black widows) exhibit strong sexual dimorphism. The female is much larger than the male. Moreover, only the female poses a danger to humans, as she is poisonous. Males are completely harmless.

Also, only female karakurts build nets and catch prey, as other species do. Males lead a different lifestyle. The whole point of their existence is to find a partner to mate with.

How a spider weaves a web

The ability to spin webs is a property that attracts special attention to spiders.

Initially, the web is a liquid protein mass produced by special glands. It hardens very quickly in the air and turns into the finest and very strong threads. They are coated with a special adhesive composition that prevents prey caught in the net from escaping.

For a spider, a web is not only a trap for finding food, but also a means of transportation (on a web it descends from a height, flies from place to place) and a way to find its home. Some spiders weave webs around both the walls of their burrows and the cocoons in which they lay eggs.

The web is not always sticky: if the spider does not intend to use it to catch prey, it releases a dry thread

Also, each type of spider weaves its own form of web - from it, scientists can, without seeing the animal, understand who they are dealing with.

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Lessons from the world around us

It is generally accepted that you need to beware of spiders. But there are more than 42 thousand species of arachnids in the world, many of them are completely harmless. Some spiders live next to people even in houses, without causing any harm to its inhabitants. Poisonous arthropods, which must be seriously guarded against, are found only in the wild.

Already from the 2nd grade, students have the opportunity to learn a lot of interesting things about arachnids. Getting to know spiders and their characteristics occurs through stories, reports, and messages. A story about spiders in grade 2 on the world around us consists of the following information:

characteristics of arachnids;
features of the internal and external structure;
diet;
reproduction;
life expectancy.

The program of the surrounding world is rich in examples and interesting facts from the life of arthropods. As a rule, information is quite accessible and understandable to a child in grade 2. In addition, students are encouraged to learn a lot of new and interesting things that will be useful for writing an essay on this topic.

Characteristic features of the structure

The physiological characteristics of arachnids are interesting, which unite them into one order. But there are also shocking factors. For example, in Africa there are spiders that are attracted to the smell of dirty socks. This fact remains a mystery even to scientists. Such features have not been recorded anywhere else in the world. Amazing Physiology Facts:

Many species of arachnids have 8 pairs of eyes, but their number can vary from 2 to 12. Interestingly, some species have acute vision, while others are completely blind.
Representatives of the family have 4 pairs of legs, with 6 knees on each leg. Their brain takes up 25% or ¼ of their body volume.
Spiders don't have ears. They hear perfectly using the hairs on their legs. The sense of smell works according to the same program.
They are predators, their diet consists of insects, small animals, and lizards.
They do not have a circulatory system or blood in the usual sense. The substance that ensures communication between organs is hemolymph. It has a bluish tint. The color is caused by copper particles that oxidize in the air.
At one time, the spider lays several thousand eggs, but only a select few are destined to survive. Not all babies are born. Only 1 in 100 spiders will survive to adulthood.
Darwin's spider spins the strongest thread in the world. Silk thread is several times stronger than material for body armor. The web of different spiders can vary significantly in quality.
Some representatives of arachnids are quite edible. For example, in Asia, well-cooked spider is considered a delicacy.
These creatures are capable of amazing movement speed. They cover a distance of half a meter in just 1 second.
The only species found only in Hawaii has a smiley face design on its back.
The first place in beauty is occupied by the Peacock spider . The color of the male can shimmer in different colors of the rainbow. Its bright tail is especially beautiful. He needs a luxurious appearance to attract a female. If she does not pay attention to the “peacock,” the elegant arthropod begins to dance.

The thread that any representative of the squad weaves can be considered a masterpiece. If you roughly stretch it around the equator, it will weigh only 340 g.

Serebryanka

We have already mentioned the water spider earlier - this is the silverback spider. Interesting facts are associated with his lifestyle. Agree that not every living creature will adapt to living under water. Moreover, he builds his house for himself, weaving a dome from threads. He himself fills it with air in a very interesting way.

The spider has eight eyes, but has poor vision. Therefore, the organ of touch for him is the villi on his paws. With their help, he gets his food. Although he cannot see, he perfectly feels all the vibrations. As soon as some crustacean gets into his net, he immediately rushes at it and takes it with him to his home. There he eats it.

Reproduction of arachnids

All arachnids are dioecious. The female cross spider lays eggs in the fall in a cocoon woven from a silky web, which she places in secluded places (under stones, stumps, etc.). By winter, the female dies, and spiders emerge from eggs overwintered in a warm cocoon in the spring.

Other spiders also take care of their offspring. For example, a female tarantula carries her young on her back. Some spiders, having laid eggs in a web cocoon, often carry it with them.

Among the arachnids there are species whose poison is dangerous for humans and farm animals (karakurt, scorpion), human parasites (itching itch) and mites that carry pathogens that are painful to humans and animals (taiga tick, etc.).