Earthworm (lat.Lumbricidae) belongs to the class of invertebrate animals and suborder of earthworms (Haplotaxida). Its body consists of ring-shaped segments, the number of which can reach 320! These animals are widespread in all corners of our planet. There are not only them in Antarctica. Very often children are interested in how earthworms move. In this article we will discuss this issue in detail, and at the same time we will learn about their appearance, way of life and method of reproduction.
The way of life of earthworms
If in the morning or after a rain walk in the garden,garden, then, as a rule, you can see on the ground a small pile of soil ejected by worms, and in puddles to see them themselves. Due to the fact that these individuals creep out to the surface of the earth after the rain, they are followed by such a name. The earthworm (the photo above shows this invertebrate animal) also creeps out to the earth's surface at night. As a rule, he prefers a humus rich soil, so it can rarely be found in sandstones. Does not like earthworm and marshy soils. These features are explained by the physiological characteristics of Lumbricidae. The fact is that the worms breathe the entire surface of their body, covered with mucous epidermis. In a land saturated with moisture, too little air is dissolved. As a result, the earthworm suffocates there. By the way, this explains his behavior during the rain. Dry soil is also harmful for representatives of Haplotaxida: their skin dries up and the breath stops. In wet and warm weather earthworms (the photo below shows Lumbricidae in all "glory") are kept closer to the surface of the earth. With a decrease in temperature, as well as with the onset of the dry period, they creep into the deep layers of the soil.
Appearance of earthworms
Adult individuals reach 30 centimeters in length,although there are individual specimens of a larger size. The body of the earthworm is slippery, smooth, has a cylindrical shape, consists of segments - piece-work rings. This constitution is explained by the way of life of Lumbricidae: a similar structure facilitates the process of movement in the soil. The number of piece-making rings reaches two hundred. The surface of the body, which could conventionally be called a back, convex, ventral - flat and lighter. On the body of the earthworm, where its front end is completed, there is a thickening, which is called a girdle. In it there are special glands secreting sticky liquid. When reproducing from the girdle, an egg cocoon is formed, eggs develop in it.
How do earthworms move?
Representatives of Haplotaxida creep.First they stretch the front end of their body and cling to special bristles that are located on the ventral side of the rings, due to unevenness of the earth's surface. After this, the muscles contract, and the back of the body is pulled forward. The movement of the worm in the earth is characterized by the fact that it paves the way in the soil. At the same time, with the pointed end of the body, he spreads the earth, and then squeezes between its particles. It is also interesting how earthworms move in denser layers. In the process of motion, they swallow the earth and pass it through the intestine. The soil of the worms, as a rule, is swallowed at a considerable depth, but is thrown out through the anus already above, near its own mink. It can often be observed in the summer on the surface of the earth in the form of lumps and elongated "laces".
Earthworm and its biology
Worms have well developed musculature,thanks to which a similar method of movement became possible. Their muscles are under the epidermis, in fact, they together with the skin form a kind of skin-muscular sac. The musculature is located in two layers. Directly under the epidermis are the annular muscles, and below them - the second, thicker longitudinal layer (consists of contractile long fibers). When compressing the longitudinal musculature, the body of the earthworm becomes thicker and shorter. When the ring muscle contraction, on the contrary, is long and thin. The alternate contraction of both layers of muscles, carried out under the influence of a branching nervous system in the muscular tissue, and causes the movement of Lumbricidae.
Moving worms is much easierdue to the presence on the lower part of the body of small setae. They can be felt if you hold a wet finger on the abdomen of the worm from the back to the front end. Due to these bristles, earthworms not only move in the soil, but also "grab" for the ground when they are being pulled. They also help to rise and fall on the already done ground motions. This concludes with the question of how the earthworms move, and we pass to no less interesting facts about the life of Lumbricidae.
Circulatory system
The circulatory system of earthworms consists oftwo longitudinal vessels - the abdominal and dorsal, as well as the branches connecting them. Due to the muscular contraction of the walls, blood flows throughout the body. The blood of scarlet earthworms. With its help, the connection between internal organs is established, and also metabolism is carried out. Circulating, the blood carries nutritional compounds from the digestive organs, as well as oxygen from the skin. At the same time carbon dioxide is extracted from the tissues. In addition, the blood removes unnecessary and harmful compounds in the organs of secretion.
Nutrition of earthworms
The basis of nutrition representatives of Haplotaxidamake up the rotten plant remains. As a rule, at night, earthworms drag leaves, stems and so on into their holes. In addition, they can pass through their intestines rich in humus soil.
Earthworm irritation
Special sensory organs earthworms do nothave. External irritations they perceive thanks to the nervous system. Worms have a strong sense of touch. Nerve cells responsible for this, are located on the entire surface of the skin. The sensitivity of earthworms is so great that the easiest soil vibrations cause them to hide in the burrows or in deeper layers of the earth with the maximum possible speed. However, the value of sensitive nerve endings is not limited only by the sense of touch. Scientists have found out that with the help of these cells, earthworms can sense the rays of light. So, if the worm at night to direct the beam of the lantern, then it will quickly hide in a safe place.
Answer animals for any irritation,carried out by the nervous system, is called a reflex. It is customary to distinguish between reflexes of various kinds. Thus, reducing the body of an earthworm from touching it, as well as its movement under sudden lighting, is a protective function. This is a protective reflex. Experiments of scientists have shown that earthworms can smell. Thanks to the sense of smell, they find food.
Reproduction
Earthworms reproduce sexually, althoughin general, the primordiae are hermaphrodites. Each representative of Haplotaxida has male organs called testes (in which spermatozoa develop), as well as female organs called ovaries (in them egg cells are formed). The earthworm lays its eggs in a mucous cocoon. It is formed from a substance that is released through the belt. Then the cocoon in the form of a clutch slides off the body and contracts at the ends. He remains in the ground until the young worms leave it. The cocoon serves to protect eggs from dampness and other adverse effects.
And why do we need worms?
This section will be useful for those who think,that earthworms are only needed for fishing. Of course, the fisherman without them has nothing to do without them on the river, but this is not all good from the representatives of Lumbricidae. The role of the earthworm in nature is so great that it is impossible to overestimate it. They contribute to the decomposition of organic matter in the soil. In addition, earthworms enrich the land with a valuable fertilizer - humus. They are also a kind of indicator: if the soil contains many worms, it means that it is fertile.
A full understanding of the role of Haplotaxida has come tohumanity relatively recently. However, even now, many farmers prefer to use chemical fertilizers, despite the fact that they kill all living things. Today, chemists have found an alternative - vermicompost and biohumus. In fact, this is a magic wand for the earth, because they contain a large amount of phosphorus, potassium, nitrogen, that is, those substances that are vital for plants for their full growth.
Conclusion
Earthworms are the most important link in thesoil formation. Let's look at the process. In the fall, the foliage falls from the trees and covers the whole surface of the earth. Immediately after this, the soil bacteria take over and decompose the leaves to the compost stage. And then the baton is picked up by worms, which process the foliage to the stage of a vermicompost. Thus, valuable fertilizers fall into the soil.
