Earthworm (lat. Lumbricidae) belongs to the class of invertebrate animals and the suborder of earthworms (Haplotaxida). His body consists of ring-shaped segments, the number of which can reach 320! These animals are widespread in all corners of our planet. They are not only in Antarctica. Very often, children are interested in how earthworms move. In our article, we will analyze this issue in detail, and at the same time we will learn about their appearance, lifestyle and method of reproduction.
Earthworm Lifestyle
If in the morning or after rain to walk through the garden, the garden, then, as a rule, you can see on the ground small heaps of soil thrown out by worms, and in the puddles you can see them yourself. Due to the fact that these individuals crawl to the surface of the earth after the rain, such a name was attached to them. The earthworm (photo above shows this invertebrate animal) also crawls to the earth's surface at night. As a rule, he prefers humus-rich soil, so it can rarely be found in sandstones. He does not like earthworm and marshy soils. These features are explained by the physiological features of Lumbricidae. The fact is that worms breathe the entire surface of their body, covered with mucous epidermis. Too little air is dissolved in moisture-saturated earth. As a result, the earthworm is suffocating there. By the way, this also explains his behavior in the rain. Dry soil is also detrimental to representatives of Haplotaxida: their skin dries up, and breathing stops. In humid and warm weather, earthworms (the photo below shows Lumbricidae in all its glory) stay 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.
The appearance of earthworms
Adult individuals reach 30 centimeters in length, although there are individual specimens of larger sizes. The body of the earthworm is slippery, smooth, has a cylindrical shape, consists of segments - piece rings. This constitution is explained by the lifestyle of Lumbricidae: a similar structure facilitates the process of movement in the soil. The number of piece rings reaches two hundred. The surface of the body, which could conditionally be called the back, is convex, and the abdominal surface is flat and lighter. On the body of the earthworm, where its front end is completed, there is a thickening called the girdle. It contains special glands that secrete a sticky liquid. When propagating from the girdle, an egg cocoon is formed, eggs develop in it.
How do earthworms move?
Representatives of Haplotaxida crawl. First, they stretch the front end of their body and cling to special bristles, which are located on the ventral side of the rings, for the unevenness of the earth's surface. After this, muscle contraction occurs, and the back of the body is pulled forward. The movement of the worm in the ground is characterized by the fact that it makes moves in the soil. At the same time, with the pointed end of the body, he pushes the earth apart, and then squeezes between its particles. It is also interesting how earthworms move in denser layers. In the process of movement, they swallow the earth and pass it through the intestines. Worms, as a rule, swallow the soil at a considerable depth, and are thrown out through the anus already at the top, near their 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 muscles, 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 muscular skin bag. The muscles are located in two layers. The ring muscles are located directly below the epidermis, and below them is the second, thicker longitudinal layer (consists of contractile long fibers). When the longitudinal muscles are compressed, the body of the earthworm becomes thicker and shorter. When contracting the ring muscles, on the contrary, it is long and thin. The successive contraction of both muscle layers, carried out under the influence of the nervous system branching into the muscle tissue, determines the movement of Lumbricidae.
The movement of the worms is greatly facilitated by the presence of small setae on the lower body. You can feel them if you hold a wet finger across the abdomen of the worm from the back to the front end. Thanks to these bristles, earthworms not only move in the soil, but also “clutch” the earth when they are trying to pull them out. They also help to rise and fall along already done earth passages. At this point, we will finish with the question of how earthworms move, and move on to no less interesting facts about the life of Lumbricidae.
Circulatory system
The circulatory system of earthworms consists of two longitudinal vessels - the abdominal and dorsal, as well as the branches connecting them. Due to muscle contraction of the walls, blood flows throughout the body. Blood from earthworms is scarlet. With its help, a connection is established between the internal organs, and a metabolism is also carried out. While circulating, the blood carries nutrient compounds from the digestive organs, as well as oxygen from the skin. At the same time, carbon dioxide is removed from the tissues. In addition, blood removes unnecessary and harmful compounds to the organs of excretion.
Earthworm Nutrition
The basis of the nutrition of Haplotaxida representatives is half-rotted plant remains. As a rule, at night, earthworms drag leaves, stems, etc. into their burrows. In addition, they can pass humus-rich soil through their intestines.
Earthworm irritation
Earthworms do not have special sensory organs . They perceive external irritations due to the nervous system. Worms have a very developed sense of touch. The nerve cells responsible for this are located over the entire surface of the skin. The sensitivity of earthworms is so great that the slightest vibrations of the soil make them hide at the highest possible speed in burrows or in deeper layers of the earth. However, the importance of sensory nerve endings is not limited only to the function of touch. Scientists have found that with the help of these cells, earthworms are able to sense rays of light. So, if you direct a beam of a flashlight to the worm at night, then it will hide at high speed in a safe place.
The response of animals to any irritation caused by the nervous system is called a reflex. It is customary to distinguish between reflexes of various kinds. Thus, the contraction of the body of an earthworm from touching it, as well as its movement in sudden light, is a protective function. This is the protective reflex. Scientists have shown that earthworms can smell. Thanks to the sense of smell, they find food.
Breeding
Earthworms reproduce sexually, although the primary ones are hermaphrodites. Each representative of Haplotaxida has male organs, which are called testes (sperm develop in them), as well as female organs, called ovaries (eggs are formed in them). An earthworm lays its eggs in a mucous cocoon. It is formed from a substance that is secreted through the girdle. Further, the cocoon in the form of a sleeve slides off the body and is pulled together at the ends. He remains in the ground until young worms come out of it. Cocoon serves to protect eggs from dampness and other adverse effects.
What are worms for?
This section will be useful for those who think that earthworms are only needed for fishing. Of course, a fisherman without them has nothing to do without them on the river, but this is not all the benefit of 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 earth with valuable fertilizer - humus. They are also a kind of indicator: if the soil contains many worms, then it is fertile.
A full understanding of the role of Haplotaxida came to humanity relatively recently. However, even now many farmers prefer to use chemical fertilizers, despite the fact that they kill all living things. Today, chemicals have found an alternative - vermicompost and vermicompost. In fact, this is a magic wand for the earth, because they contain a large amount of phosphorus, potassium, nitrogen, that is, precisely those substances that are vital to plants for their full growth.
Conclusion
Earthworms are the most important link in soil formation. Let's take a look at the process. Autumn leaves fall from the trees and cover the entire surface of the earth. Immediately after this, the soil bacteria take up the matter and decompose the leaves to the stage of compost. And then the worms pick up the baton, which process the foliage to the stage of vermicompost. Thus, valuable fertilizers enter the soil.