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Arthropod type: general characteristic, classification

Our planet is very replete with various creatures, a lot of various animals and plants we have. But in this paper we will discuss in detail the type of arthropods. A general description of these living things will also be presented in the article.


This is the largest and richest type in the animal kingdom. There are about a million species. Their number is one third of all living organisms of our planet, both living at this time and extinct. Before we get to the question "General characteristic of arthropod type" (the 7th form of the general education school is obliged to introduce the children to its representatives), it is necessary to know that a large number of creatures are still unexplored, the actual number of them can theoretically reach ten or more millions.

They are distributed everywhere: in the seas, oceans, freshwater springs, on land. Depending on which ecosystem the particular species has chosen, one can judge about evolution and food preferences. Type of arthropods, the general characteristic of which is our main task, is diverse, we propose to classify classification for classification.


We have already mentioned that the type has a large number of creatures, but in spite of such diversity, they all have a relatively similar body structure. Considering the type of arthropods (the general characteristic), let's note a similar line - an external rigid skeleton, consisting of chitin. Some species have an exoskeleton containing lipids, proteins and calcium carbonate. This outdoor suit provides them with protection and support of the body. The walls of the armor are also attached to the muscles.

Important is the fact that all representatives are susceptible to molt, this process occurs due to the fact that the exoskeleton does not grow, and during the growth of the animal a larger house is needed.


The type of arthropods is rich and diverse. The general characteristic also includes such a feature as segmentation. The whole body is divided into segments. Sometimes they grow together, in this case they are called tagmata, and the process is tagmasis. One example is a fused head, chest and abdomen. Also, arthropods have processes with joints - that's where the name comes from, literally translated as "jointed legs".

Take the earliest and primitive arthropods, then each segment of their body was associated with only one pair of appendages. However, most species evolved, and limbs changed, other structures were formed, for example:

  • Oral apparatus;
  • Antennae;
  • Reproductive organs and so on.

In arthropods, the appendages can be either branched or not branching.

Feelings, gas exchange, blood circulation

Many representatives have well-developed sense organs (paired facet eyes), although some do not have this privilege. The circulatory system is unclosed, has no blood vessels.

Gas exchange occurs in several ways:

  • gills;
  • trachea;
  • lungs.

Most representatives of arthropods are dioecious, usually fertilization occurs internally, and eggs are deposited.

Arthropod type: general characteristic, classification

These are symmetrical animals. It is also important to mention that they originate from annelid worms. If you analyze well, you can see a similarity in the structure. The only thing in the course of development and evolution the first reached a high level of organization. Arthropods (the general characterization of the type, taxonomy and other issues will be thoroughly sanctified) are divided into the following main classes:

  • crustaceans;
  • Arachnids;
  • Insects.

In turn, each class is divided into groups. For example, among crustaceans are distinguished: branched, copepods and decapods. The spiders include spiders, ticks and scorpions. And insects have a very large number of detachments, such as:

  • Orthopteran;
  • Dragonflies;
  • Diptera;
  • Coleoptera;
  • Semi-feathery;
  • Hymenoptera;
  • Isotope;
  • Fleas and many others.

Let's consider each class separately.


This is a fairly diverse class, numbering about forty thousand species. Basically, they can be found in the seas and freshwater reservoirs, but there are some who have mastered the land.

Although the type of arthropods (a class of crustaceans, a general characteristic of which is discussed in this section) is very rich, but we can distinguish a number of similar features, for which at the end of the paragraph we will give a table that helps to systematize the knowledge gained.

They lead a floating, creeping or attached way of life. There are even parasites among them. As already mentioned, arthropods are characterized by segmentation of the body, there are ten to fifty of them in this class.

Let's briefly review the characteristics of a typical representative of this class, all known river cancer. From the name it already becomes clear that it lives in fresh water bodies. His role in nature and for man is very great. Note that it is possible to distinguish even externally the male and the female.

Activity is achieved at night, it feeds exclusively on plant foods, eating both live and dead prey. The size of a mature individual is from fifteen centimeters and more, they moult once a year, in young animals this process is observed several times a year.

Like other representatives of arthropods, the circulatory system is not closed, the heart looks like a five-sided bag and is attached to the back wall of the trunk. It is also important to know that the head and trunk are connected. Tactile and olfactory sensations are acute due to long whiskers. Eyes are complex and attached to flagella, which compensates for immobility of the head.




Two: cephalothorax and tail

Pair of whiskers

Two pairs

Pairs of feet

Five pairs (ten feet)



Respiratory organ


Type arthropods, class arachnids: general characteristic

As well as the previous one, it is very rich, has more than thirty thousand species of living creatures, most of which live on land, but there are also representatives of secondary water. Like crustaceans, they have a cephalothorax, in addition to this there is an abdomen. Note that segmentation is subject to change (some mites do not have a segmented body, for example, a dog).

The first segment of the body (the cephalothorax) attaches to itself six pairs of limbs:

  • Two pairs - jaws.
  • Four pairs - tentacles.

On the abdomen there are no limbs, but some representatives of this class have preserved pulmonary sacs, genital plates or spiderwebs.

Another distinguishing feature of arachnids is the outer layer, consisting of lipoprotein, which protects the body from loss of moisture. Most have poisonous and cobweb glands. As a rule, arachnids are predators, but a large group consists of parasites and herbivores. Breathing is carried out with the help of pulmonary sacs or trachea, but with spiders using these two organs. The organs of sight, touch, smell and taste are developed quite well, but some ticks have no vision completely.

Fertilization occurs internally, vigilance is observed in some species of mites and scorpions. Although this class is quite diverse, but the most important are such detachments as:

  • Spiders.
  • Ticks.
  • Scorpions.


Here is a table showing the main features of insects.




Head, chest, abdomen


Three pairs (six limbs)






Present for most representatives of the class

Nervous system


Circulatory system


This is the least studied class, but no less significant than the others, it is poorly researched by science only because it is young.

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