Not only curious students, but also many adults are interested in the question: is a spider an insect or not? Indeed, at first glance it may seem that the answer is obvious, and spiders are one of the species of insects, but this is not so. They belong to a separate class of arachnids, because they have a lot of differences with insects.
Spiders appeared on our planet a long time ago, about 400 million years ago. It is believed that they came from a crab-like ancestor. Insects appeared almost 100 million years later and created a separate class. Today on earth live about 40 thousand species of arachnids. If you look in detail at the anatomy of these creatures, then questions like "Is a spider an insect or not?" Should not arise. Everyone knows that insects have six legs, but there are eight of them in arachnids, in addition, they have eight eyes, only some species have six or two. These creatures have no teeth, but have hook-shaped jaws with special channels designed to penetrate the poison into the victim's body.
Doubts about whether a spider - an insect or not, will disappear immediately, if you consider how it eats. If the praying mantis eat the caught flies, then the arachnids can not do so because they have extraintestinal digestion. They inject the digestive enzymes, which turn an insect into soup, and spiders can only suck the contents of the shell.
Many creatures are able to spin the web, but they will not get as sturdy and elastic as the trap for the victims, which is prepared by the spider. Reproduction also causes these creatures to weave special cocoons to preserve the laying of eggs and small spiders. If we compare cobwebs to steel, then the first will be five times stronger than the second, and a yarn with a pencil will not be able to break through the airplane crashed into the network.
It is unclear why many speculate on the question of whether a spider is an insect or not: between these two classes there is a significant amount of differences. The body of these creatures is divided not into three, but only into two divisions: the abdomen and the cephalothorax. They make the web from liquid, allocated from warts located at the end of the belly. From this material, spiders build houses for themselves, make a carpet-plane on which they move for long distances, weave cocoons for eggs, nets hunt for insects.
These creatures move quite swiftly through their networks, while mosquitoes, flies and other unfortunates just stick to it. The fact is that spiders weave sticky and non-sticky threads, the first are needed to catch the victim, and the second they move. Even if they fall accidentally on the sticky part, they will not get confused, since their body has a fat cover.
Modern science has already given the exact answer to the question: "Is a spider an insect or not?", Singling out these creatures in a separate class. In the middle zone of Russia there are no spider-like life-threatening human lives, although it is necessary to behave with them carefully. A spider will never attack first, he only defends or bites at fright. The bite can only be accompanied by burning, severe pain and fever. But there are also dangerous representatives of this species: the most famous were the tarantula and karakurt. Their bite causes a common poisoning of the body, which sometimes leads to death.