The habitat of flatworms. Types of flatworms

The type of flat-worm animals , which are part of a group of bilaterally symmetric, is studied by the science of biology. Flat worms (Platyhelminthes) are not the only representatives of this group, it includes more than 90% of animals, including ringed and roundworms, arthropods, mollusks, etc.

Appearance and description of flatworms

Platyhelminthes c of the ancient Greek language is translated as "wide helminth". This invertebrate primitive worms, which lack a body cavity, designed to collect, distribute and release nutrients. Most of them are parasites, and some live in water bodies or on land with high humidity. They are characterized by a complex life cycle, during which the intermediate hosts change, until the worms settle in the organs of the final host.

Types of flatworms are diverse and common throughout the world. They number about 25 thousand.

Scientific classification of flatworms

Flat worms are referred to the realm of Bilateral (symmetrical on both sides) primary animals. In connection with some of the disputes that have arisen when trying to divide plane worms into different groups, scientists refer them to the paraphyletic group. It includes representatives of a small part of the descendants of the same ancestors.

Structure of the internal organs of a flat worm

The body of flat worms is elongated and flattened, inside not having cavities. That is, its entire space is filled with cells. Inside are layers of muscles, which together with the worm shell form a skin-muscular sac.

There are systems of internal organs:

• The digestive system is represented by the mouth and the blind (without an exit) gut. Nutrients come through the mouth, and can be absorbed through the entire surface of the body.
• The nervous system consists of the brain ganglia and nerve columns. Some classes of flatworms have primitive organs of balance, vision.
• The excretory system consists of special tubules, but most often the allocation occurs throughout the body surface.
• The reproductive system is represented by both female (ovaries) and male (testicles) genitals. Flat worms are hermaphroditic.

Differences between flat and round worms

Round worms differ from flat worms in that their cross-section has a round body. Round worms are still called nematodes. Possessing a bilaterally symmetric structure of the body, they have developed musculature. But the main difference from flatworms is that round have an internal body cavity, and flat ones do not.

Variety of classes of flatworms

Table "Flat Worms" clearly shows the division of the species into classes, which modern science has seven.

Classes of flatworms all but one (ciliated worms) are parasites. Many of them significantly affect the populations of freshwater and marine fish, reducing them.

Having the ability to parasitize on the skin, under the gills of the worms become sources of infection of various infections inside, which causes mass infection and death of fish.

Ciliated worms

Ciliated worms (turbellarians) are predators, eating small invertebrates, arthropods and even large mollusks. They completely swallow small prey or with strong sucking movements tear off pieces from it.

The body of worms can regenerate itself. A bright representative is the planaria, in which even a small part of the body grows into a full-fledged individual.

Flatworms in domestic aquariums

Helminthes can be a big problem for fans of fish breeding in aquariums.

The habitat of flatworms is mostly aquatic. As flukes, flatworms can be attached by means of an attachment disk to the surface of the gills and skin of aquarium fish.

Adult worms lay eggs, from which larvae live on the skin of fish. Gradually they creep up to the gills, where they grow, reaching puberty.

Young fish are more susceptible to parasites, weaker ones. The formation of a large accumulation of helminths on the gills leads to the death of the organ, and subsequently to the death of the fish.

Some types of flatworms enter the home aquarium with soil, live food. Their larvae can be found on the surface of algae, on the skin of new fish populated in the aquarium.

To save domestic fish from parasites, it is necessary to keep them in the baths with the addition of bicillin-5 and salt for 5 minutes.

Dangerous to human health parasites

The theme of flat worms, in particular, the problem of fighting parasites, is relevant not only for fish, mollusks and crustaceans. There is a risk of human infection with helminths, the fight against which may be long and painful.

Some types of parasites in humans and other mammals:

• Pseudophyllidea (ribbon wide). Infection can occur if there is a raw, poorly salted fish in the diet. In the human small intestine, the ribbon can live for decades, reaching a length of up to 20 m.
• Aeniarhynchus saginatus ( bovine tapeworm). The habitat of flatworms is the intestines of humans and cattle. Adhering to its walls, the helminth grows to 10 m. Larvae can be found in other internal organs, in hard-to-reach places (brain, muscles, liver), so it is often impossible to completely get rid of them. The patient may be fatal. Infection occurs when eggs of helminths enter the stomach with insufficiently thermally processed food, from dirty hands.
• Echinococcus (Echinococcus) is often found in dogs and cats, from them passing into the body to humans. Despite its small size - only 5 mm - the ability of its larvae to form Finns, paralyzing internal organs, is deadly. Larvae are able to penetrate into respiratory, bone, urinary systems. Flat echinococcus worms are often found in the brain, liver and other internal organs. A person can easily become infected with larvae isolated from the feces of a dog, which spread to the coat, and from there to all household items and food.
• Hepatic fluke - the culprit of cholecystitis, hepatic colic, disruption of the stomach and intestines, allergies. The habitat of flatworms is predominantly human liver and warm-blooded animals, biliary tract. The length of the body of the trematode does not exceed 3 cm. The peculiarity is that not only mature individuals, but their larvae are capable of reproduction.

Prevention of helminth infection

Preventive measures to hit eggs and larvae of helminths in the human body are as follows:

• You should thoroughly wash your hands with soap before each meal, after visiting public places, toilet, street, socializing with pets.
• Wash raw vegetables and fruits with warm water and soap.
• Do not eat raw meat and fish.
• Long-term heat treatment of food, especially meat, fish.
• Pay attention to timely prevention of helminthic invasions of domestic animals.
• Regularly, at least once a year, take an analysis of feces for eggs of worms.