Representatives of arachnids, characteristics of the class (photo)

The class of the Arachnids today has more than 35 thousand different species. They live in the environment almost everywhere. Among them there are completely representatives of arachnids that are harmless for humans. But there are also poisonous, and even those that parasitize the human body, while carrying various infectious diseases in parallel.

General characteristic of a class of arachnids

The characteristic features of the structure of arachnids are related to their adaptability to life on land. Representatives of the class belong to the land arthropod, having eight pairs of limbs.

Representatives of arachnids have a trunk consisting of two divisions. At the same time, its connection can be represented either by a thin partition or by a dense bond. Antennae in representatives of this class are absent.

In the front of the body are such limbs as mouth organs and walking legs. Breathing spiders with the help of lungs and trachea. The organs of vision are simple. Some species are completely absent.

The nervous system is represented by nerve nodes. Skin is hard, three-layered. There is a brain consisting of the front and rear. Circulatory organs are represented by the heart in the form of a tube and an open circulatory system. Arachnids belong to dioecious individuals.

Ecology of arachnids

The first insects, accustomed to life on land, became representatives of arachnids. They can lead both day and night active way of existence.

Class arachnids are quite extensive, so if we talk about the habitat, then its representatives are found throughout the territory of Russia. Some insects feed on catching prey in their networks, others simply attack. "Hunters" from this class mostly eat insects, but some bite people and animals, thus causing various diseases. Some representatives prefer to live on the human or animal body, while others prefer to live exclusively on cultivated plants.

Class Overview

Scientists-zoologists conditionally subdivide the arachnids into several orders. The main ones are a detachment of spiders, scorpions, mites, saltwigs.

Order Scorpions

Scorpio is an atypical spider, which is why it is isolated in a separate unit.

Arachnoid representatives of the "scorpion" type have small dimensions, not more than 20 centimeters. His body consists of three well-defined departments. On the front are two large eyes and up to five pairs of small side. The tail of the scorpion ends with a poisonous gland.

The body is covered with a thick and rigid cover. The scorpion breathes with the help of the lungs. With their habitat, they chose a terrain with a warm and hot climate. Scorpions are subdivided into two subspecies: those living in humid terrain and in dry places. The attitude to the air temperature is also ambiguous: there are subspecies preferring a warm climate and high temperature, but some perfectly tolerate the cold.

Livelihood scorpions in the dark get food, increased activity is different in the hot season. Its scorpion detects its prey, catching the vibrational movements of a potential victim.

Reproduction of scorpions

If we talk about which arachnids are viviparous, then it is the scorpions, in their majority, who breed offspring. However, there are egg-laying. The growth of embryos located in the body of the female is a rather slow process, and the pregnancy can last more than a year.

Babies appear in the light already in the shell, and after birth they immediately suck in to the mother's body with the help of special suckers. After about 10 days, the brood breaks away from the mother and begins to exist separately. The period of growing up in small individuals lasts about a year and a half.

The poisonous tail of the scorpion is the organ of attack and defense. True, the tail does not always save its owner from predators. Some animals are able to avoid shocks, and then the predator itself becomes food. But if the scorpion still stung the victim, many small invertebrates almost immediately die from the injection. Larger animals can live a day or two.

For a person, the scorpion's aggression does not end with a lethal outcome, but in modern medicine there are cases with very serious consequences. At the site of the lesion, there is a swelling, which can be quite painful, and the person becomes more sluggish and may experience attacks of tachycardia. After a couple of days, everything passes, but in some cases the symptomatology persists for a longer period.

Children are more sensitive to the effects of scorpion poison. Among the toddlers, cases of death were recorded. In any case, after an insect bite, you should immediately seek qualified help from a medical institution.

Detachment of Solpugi

Recall that we are considering the class Arachnids. Representatives of this detachment are widespread in countries with a warm climate. For example, very often they can be found on the territory of the Crimea.

Scorpions are distinguished by a large dismemberment of the trunk. At the same time, the solid jaws of the salted pigs perform the function of catching and killing the victim.

Saltpacks have no poisonous glands. Attacking a man, the saltworts damage the skin with sharp jaws. Quite often, the infection occurs simultaneously with the bite. The consequences are: inflammation of the skin at the site of injury, accompanied by pain.

This was a characteristic of the arachnids, the order of the solpuga, and now consider the next detachment.

Spiders

This is the most numerous detachment, numbering more than 20 thousand species.

Representatives of different species differ from each other only in the form of a web. Ordinary house spiders, which can be found in almost any home, weave a web, shaped like a funnel. Poisonous representatives of the class create a web in the form of a rare hut.

Some spiders do not weave cobwebs at all, but lie in wait for their prey, sitting on flowers. The coloring of insects in this case is adapted to the shade of the plant.

Also in nature there are spiders that prey on prey, just jumping on it. There is one more special category of spiders. They never stay in one place, but constantly move in search of prey. They are called wolf spiders. But there are hunters who attack from an ambush, in particular, a tarantula.

The structure of the spider

The body consists of two sections connected by a septum. In the front part of the trunk are the eyes, under them are solid jaws, inside which there is a special channel. It is through him that the poison enters the body of the insect from the glands.

The sensory organs are the tentacles. The spider's body is covered by a light, but firm cover, which, as it grows, is dumped by the spider, then later replaced by another.

On the abdomen are small glandular growths, which produce a web. Initially, the threads are liquid, but quickly become solid.

The spider's digestive system is quite unusual. Catching the victim, he injects into it the poison, which in the beginning kills. Then the gastric juice enters the body of the victim, completely dissolving the insects of the caught insect. Later, the spider simply sucks the resulting liquid, leaving only the shell.

Breathing is performed with the help of the lungs and the trachea located in the front and back of the abdomen.

The circulatory system, as in all the representatives of arachnids, consists of the heart tube and non-closed blood circulation. The spider's nervous system is represented by nervous nodes.

Spiders reproduce by the method of internal fertilization. Females lay eggs. Subsequently, small spiders appear from them.

Squad of Ticks

The detachment includes small and microscopic arachnids with an undivided body. All mites have twelve limbs. They feed on representatives of arachnids, both solid and liquid food. It all depends on the species.

The digestive system of ticks is branched. There are also organs of excretory system. The nervous system is represented by the neural chain and the brain.

Ticks multiply by laying eggs. Representatives of the class are heterosexual. Their life expectancy reaches half a year, no more. But there are also real long-livers.

Dwell mites, like spiders, everywhere: in houses, gardens, fields. Some representatives are capable of causing significant harm, damaging plants and grain. Quite often it is the mites that carry the disease.

Characteristics of some representatives of the class Arachnids

Spiders of some species do not use nets during hunting. Among them is a spider-sidearm. The hunter is waiting for prey, hiding on the flower petal. The greenish-yellow color of the shell almost exactly repeats the color of the sepals, helping the spider to disguise itself. He is not able to notice even the bees. The spider attacks the victim at a time when the insect is lowering its head into the stamens.

Here is another characteristic of arachnids (squad mites). Consider a taiga tick. It chose the Far East for its habitat, but it also occurs in the European part of the country.

The size of the male is about 2 mm, while females are almost twice as large. Larvae actively parasitize on small animals, but as the growth takes place and the change of the "master". The tick is already moving to hares or chipmunks. Sufficiently developed and strong individuals choose a prey for cattle.

The oral apparatus, as well as at all representatives of a class, settles down ahead of a trunk and is presented by a proboscis and strong sharp teeth. With their help, the tick is held on the body of the victim until it is completely saturated.

This was a brief description of some representatives of the class arachnids.

We hope that the information will be useful to you.