Most of the species of organisms that exist on our planet, for many centuries and millennia, followed the path of evolution and biological progress. However, there are such representatives of wildlife who have achieved greater success in a completely different way - by regressing or simplifying the organization. How did this happen and how can it be useful? It turns out that this is a necessary condition for leading a parasitic lifestyle. Especially successful in adapting to life at the expense of others was managed by different types of worms - helminths, which we will talk about later.
The structure of parasitic worms
Helminths, or parasitic worms, include organisms that have adapted to live inside mammals and other creatures, including humans, causing serious damage to their health and even the life of their host through their vital functions. Each parasitic worm is able to replace several hosts during the life cycle. This is necessary to preserve the number and survival of eggs, that is, future offspring.
Of course, each class has its own representatives, who, in turn, are endowed with features that distinguish them from each other and allow them to be unique parasites. However, several common characteristics that each parasitic worm possesses can be distinguished.
- In the structure of the body there are organs that serve to consolidate in the body of the host. Examples: suction cups, hooks.
- The presence of special integuments of the body that do not allow the host body to digest them.
- Laying offspring several million eggs at a time and the complex structure of the reproductive system (most often hermaphroditic type).
- Regression in the structure of all senses. The digestive and excretory systems are as simple as possible in structure and functionality. Breathing is carried out by the entire surface of the body.
- The ability to reproduce at the larval stage.
All these features make different types of parasitic worms simply universal and very dangerous creatures with simply colossal survival.
Classification of parasitic worms
In total, two main groups of similar organisms can be distinguished.
- Type Flatworms. It is the parasitic forms that are the classes of the Tape, Suckers. Types of parasitic flatworms of this type: bovine tapeworm, pork tapeworm, wide ribbon, echinococcus, cat fluke, schistosome, paradoxical leukochloridia, flukes and others.
- Type Roundworms. Class Actually roundworms. Examples of organisms: anisacides, pinworms, roundworms, hookworms, rishts, whipworms, trichinella, filarias and others.
Types of parasitic worms are very diverse. In total, scientists distinguish about 300 representatives who can live in the body of a person, not to mention other animals. The harm caused by these creatures is truly sometimes irreparable.
Class Actually roundworms: parasitic forms
Compared to flatworms, this group is more highly developed in terms of body structure. So, this class of parasitic worms has the following features.
- Dichotomy. Males have testes and the ejaculatory canal, which opens into the hind gut. Females are ovaries, uniting into a common vagina. Reproduction is only sexual.
- Low ability to regenerate lost parts of the body, as the number of cells is limited.
- The anus appears. Thus, the digestive system has the appearance of a simple tube, which consists of the oral part, the middle and anal canal.
- The nervous system is represented by ganglia. So far, quite simple, but nonetheless already existing.
- Excretory system such as protonephridia.
- The integument of the body is three-layered, the outer is hypodermis. It performs not only a protective role, but also a skeleton function. In it, metabolic processes take place.
- The center of the body is occupied by a pseudo-target - this is the cavity in which the liquid is located. She plays the role of blood.
A parasitic worm of this class can lead a different lifestyle. So, bio- and geoparasites are isolated. Biohelminths should include those species that replace several hosts during life and thus spread. To geohelminths - those whose distribution occurs in the external environment.
Vlasoglav
This parasitic roundworm belongs to geohelminths, because it needs two conditions for propagating growth and development:
- the presence of the human body;
- ordinary wet ground.
With such modest needs, it is not surprising that the prevalence of this helminth is very high. By itself, an adult worm rarely reaches a length of 5 cm. Males and females differ in the posterior end of the body: in the former it is thickened and spirally twisted, and in the latter it is an elongated filiform.
The parasite feeds not on the contents of the human intestines, namely on its blood, therefore, treatment for its effects requires special. It deeply affects the intestinal wall, therefore, it can cause inflammatory processes. It affects the body with the products of its vital activity.
The disease caused by this creature is called trichocephalosis. Infection occurs through tactile contact with dirty vegetables and fruits, water. It is on these objects that the barrel-shaped eggs of parasites are found, which reach maturity inside the body in a few weeks.
Eggs with feces are hatched and developed in the external environment - in warm, moist soil. Again, again swallowed by man.
Pinworm
A parasitic roundworm, which occurs in almost every second child, can also be present in an adult. Small white parasites, rarely reaching a length of more than 5 mm. Their main feature that allows them to spread so widely is the absence of a change of owner. They parasitize in one organism, feeding on the contents of its intestines.
At night they leave the anus and a lot of eggs are laid on the circumference of the anus. This causes the child itching and irritation, he begins to unconsciously scratch this place in a dream. So the eggs fall under the nails, from where again to the oral cavity and to surrounding objects.
After laying the eggs, the female dies. Therefore, in the case when re-infection is not observed, it is possible to cure the body without medication. Pinworm disease is called enterobiosis.
Trichinella
The parasitic worm is very small in size. Rarely reaches a length of 3.5 mm. The males are even smaller. Belongs to biohelminths. Parasitize in humans and mammals. The muscles are affected, as they settle and settle in them. Each female is capable of laying a lot of eggs (up to 2 thousand) and then die.
After about two months, larvae emerge from the eggs, which, with the flow of lymph and blood, spread throughout the body, becoming stronger in the muscles and disrupting their normal functioning. The disease is called trichinosis, with severe contamination with parasites, it can be fatal.
Type Flat, Grade Tapeworms
Representatives of this type can be both free-living and parasitic forms. All of them are characterized by some features in the structure of the body.
- Bilateral symmetry.
- Lack of body cavity.
- Colossal ability to regenerate.
- The most simplified digestive system.
- The vast majority of species are hermaphrodites.
The main parasites are two classes - Tape and Suckers.
Wide Ribbon and Echinococcus
A wide ribbon is a parasitic tapeworm that replaces three hosts for life. The first of them are crustaceans, the second - fish, the third and final - man. The length of these helminths can be up to several meters. They feed on the contents of the intestines, which cause a sharp starvation and lack of substances for the vital activity of the host.
Infection occurs through fish that a person eats. The disease is called diphyllobothriasis.
Echinococcus is also a parasitic tapeworm. Its peculiarity is that man is an intermediate host for him. The main ones are dogs and wolves. However, once in the human body, the larvae are carried by a blood stream. Then larvae come out - oncospheres. They form a bubble, which begins to grow gradually. This disease is called echinococcosis.
Both types of parasite considered have several rows of tenacious hooks for rooting in the host organism, thereby causing additional harm and causing painful sensations. Also common and terrible parasites from tape are tapeworms - bovine and pork.
Schistosome and leukochloridium paradoxical
Which parasitic worm is characterized by a host change involving gastropods? The answer is: for many flukes. These are worms that have numerous suckers. It is they who are fixed in the body of the ultimate master, which is man.
Schistosome is a species that becomes infected when swimming in water, where larvae swim. They feed on the blood of mammals. Their main danger is spikes on the body, with which they pierce the walls of internal organs, causing their inflammation, the appearance of cysts, tumors. It is difficult to recover from these parasites.
Leukochloridium is paradoxical - it is he who uses gastropod mollusks as one of the hosts. The final item for life, this worm chose birds. It is interesting that in the body of the cochlea the larva grows and becomes so convex that it is visible from the outside. It resembles a bright green caterpillar, which attracts birds. They peck at it, as a result, infection occurs.
Parasitic Worm Control Measures
The fight against parasitic worms is not an easy task. The most important thing is the careful observance of all necessary preventive measures. Of great importance is personal and public hygiene. Without this, it is impossible to fight with helminth eggs. Secondly, it is certainly a good heat treatment of food.
Treatment for each specific type of parasite is strictly individual and is prescribed by a doctor. Most often these are tablets (Vermox, Dekaris, Pirantel, etc.). However, in more severe cases, injections, droppers, radiation and other types of exposure are necessary.