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Ascaris is a round parasitic worm that causes a disease called ascariasis in humans and parasitizes in the small intestine.
An adult individual does not have organs of attachment to the human intestine and is kept in it due to constant movement, which has a direction towards the intake of food masses. The body of the worm is not divided into segments, it has a rounded shape.
The main aromorphoses of the type of roundworms, which include roundworms, are as follows:
The presence of the posterior intestine, the presence of the anus.
The primary body cavity is a pseudo-goal.
Male and female parasites.
The upper epithelial layer of roundworm is formed by a dense, inextensible cuticle, which has a flexible structure. Under it is the hypodermis, which performs the function of a kind of skeleton of the worm, and also contributes to its protection from mechanical injuries, from human digestive enzymes and from toxic effects. It is in the hypodermis that metabolic processes take place. Under the hypodermis are the muscular sac. The body of the worm is filled with fluid, which gives it elasticity.
Appearance of roundworm
Adults may be whitish-yellow or whitish-pink. The shape of their body is spindle-shaped, pointed on both sides.
Females can reach 40 cm in length, males are almost half as long, their maximum body length is 25 cm. The body of the female is straight, while the rear end of the male has a characteristic bend towards the abdomen.
Digestive system of roundworm
Around the mouth of the worm are sensitive tubercles, which are called papillomas. There are three of these tubercles. This structure of the oral apparatus allows the worms to swallow large volumes of semi-liquid food, as they feed on the contents of the human intestine.
The digestive system of roundworms is represented by the esophagus and tubular intestine. It is not completely reduced in these worms, so food is finally digested in their ectodermal hindgut. Processed food worms are removed through the anus.
The reproductive system of roundworm
Roundworms reproduce sexually. Their genitals are represented by convoluted filamentous tubes. Roundworm individuals are dioecious.
The reproductive system of the female is represented by two ovaries with oviducts, 2 uterus and 1 vagina. Every day, females can lay 200-240 thousand eggs, which, together with feces, are brought out. The eggs themselves are covered with a dense protective shell, consisting of five layers. It protects them from damage and provides food for the larvae.
Males have reproductive organs and phagocytic cells. They are located at the posterior end of the elongated body. It is in phagocytic cells that the accumulation of insoluble metabolic products occurs. The male has one testis, which passes into the vas deferens and into the hindgut.
Ascaris nervous system
The nervous system of the worms is formed by a ganglion, which has an annular shape. Nerve endings branch off from this ring and penetrate the body of the roundworm. The tactile cells of the worms are located in the pits and tubercles. They provide chemosensitivity of parasites and make it possible to find the most favorable places for them in the intestine.
The respiratory system of roundworms is not developed. Oxygen is poison to these anaerobic creatures.