No wonder flat and round worms have earned the glory of dangerous parasites of humans and animals. Therefore, knowledge about the features of their structure and activity will not harm each of us. What are the similarities between flat and round worms, what are the differences, how can they be dangerous? You will find answers to these questions in our article.
What are the similarities between flat and round worms?
The body of both flat and round worms is formed by real tissues that form their organs and systems. Recall that intestinal animals did not have these structures. Jellyfish and polyps are composed of separate specialized cells. A common sign is the elongated body shape of both types of worms, and the size of their representatives, which vary significantly.
So, a flatworm, a parasite of cattle - bovine tapeworm, grows up to 10 meters. But the round pinworm barely exceeds 10 mm. However, their size does not affect the scale of harm, which is equally large.
Comparison of flat and round worms
| Signs for alignment | Type Flatworms | Type Roundworms |
| Habitat | Water and body | Organized |
| Body cavity | Is absent | Primary |
| Body layers | Ecto, ento and mesoderm |
| Musculoskeletal system | Muscular skin bag |
| Digestive system | Closed, consists of a mouth opening and a blindly closed intestine | Through type, formed by the oral and anal openings, as well as the intestines |
| Circulatory system | Is absent |
| Respiratory system | None: gas exchange is carried out through the integument of the body |
| Excretory system | Thin tubules opening with specialized pores | Consists of long tubules that open outwards with a single hole |
| Nervous system | Nodal type |
| Reproductive system, type of fertilization and development | Mostly hermaphrodites, internal, indirect | Dioecious, internal, indirect |
Habitat
Representatives of flatworms, like roundworms, parasitize in the internal organs of many animals and humans. Moreover, the first are attached to their walls with the help of special structures located on the front side of the body. For example, the hepatic trematode has an oral and abdominal sucker, and pork tapeworm has a proboscis with hooks. Roundworms of such organs do not have attachments, so they have to constantly move towards the food masses. So, roundworms that parasitize in the lumen of the human small intestine "travel" through the body with a stream of blood and oxygen.
Among flatworms, there are also free-living species. Various types of planarians have developed fresh, saline reservoirs, as well as forest litter. They feed, hunting smaller animals: crustaceans, hydroids, insect larvae and other worms.
Lifestyle
What are the similarities between flat and round worms? First of all, in a parasitic way of life. To reach adulthood, they must go through a complex life cycle. So, roundworms - human parasites, which are called trichinella, in the process of development replace several hosts. Pigs infect their larvae by eating various scraps and meat of other infected animals. Then there is their development and the introduction of worm cysts into muscle fibers. A person becomes infected with Trichinella, eating poorly fried pig meat. In the intestine, the parasite larva leaves the cyst, migrates, and invades muscle tissue.
The flatworm - the cat fluke parasite - in its life cycle develops in the body of two intermediate hosts: the mollusk and the fish. Only after that he reaches a sexually mature stage in the ducts of the human liver and fish-eating animals: cats, dogs, wolves.
Body cavity
Based on the data that our table contains, roundworms have a number of more progressive structural features. One of them is the appearance of a body cavity. In flatworms, it is completely absent. Their body is flattened in the dorsal-abdominal direction and has the shape of a leaf or ribbon. They do not have gaps between the organs, because they are filled with a kind of connective tissue - the parenchyma.
In roundworms, the primary cavity of the body appears. Its characteristic feature is the lack of its own lining. Between the organs is constantly circulating abdominal fluid, performing the most important functions. It carries oxygen to tissues and organs, and to the excretory ducts - the final metabolic products. Since the abdominal fluid is under pressure, it is involved in maintaining the constant shape of the body of roundworms.
Digestion
Significant differences are these types of animals and in the structural features of the digestive system. Representatives of flatworms, regardless of their lifestyle, have a mouth opening and intestines that blindly end. This means that they cannot simultaneously absorb food and excrete undigested residues. And tapeworms are completely devoid of intestines, since they already absorb digested substances from the lumen of the small intestines of animals.
Roundworms are parasites that have a through intestine. This leads to a more intense metabolism. Due to this structure, the removal of undigested residues does not interfere with the receipt of new portions.
The structure of organ systems
In general, organ systems of flat and round worms have much in common. Their integument is represented by a skin-muscle bag. This structure consists of integumentary epithelial cells and several layers of muscles located under them. This structure makes possible the active movement of worms in space. Gas exchange and the process of separation of substances also have the same mechanism.
The nervous system, consisting of nodes and processes, forms a variety of sensory organs of worms. They are mainly located on the front end of the body. These are photosensitive eyes, tactile bristles or papillae, organs of chemical perception and balance. Despite the significant difference in the type of reproductive system, flat and round worms have the same developmental stages. This is an egg, a larva and an adult organism.
The meaning of flat and round worms
Understanding the similarities between flat and round worms, it is necessary to mention the biological role of these animals. Parasitizing in living organisms, they poison their own metabolic products. For example, flukes cause inflammation of the liver, destruction of the walls of the bile ducts. Tapeworms, absorbing nutrients and vitamins from the host, lead to its depletion, weakness, and even loss of consciousness. Round parasites destroy many parts of plants, causing significant damage to the crop. Gall, stem and wheat nematodes are widely known.
Flat and round worms pose a serious threat to human health. To avoid infection, it is necessary to eat well-washed fruits and vegetables, thermally processed meat and fish, do not drink raw water, adhere to personal hygiene rules.
So, flat and round worms have many similar structural features. These include: habitat, elongated form, parasitic lifestyle, the presence of three layers of the body, the absence of the circulatory system. However, roundworms have a number of progressive features. First of all, this is the presence of the primary cavity and the through intestine.