All representatives of multicellular animals differ in the level of organization, characteristic features of life processes and are combined into special taxa - types. There are 7 in total. A type of flatworm is one of them. These creatures have perfectly adapted to the conditions of existence and occupy their biological niche. How do flatworms feed? Look for answers in our article.
General characteristics of flatworms
Representatives of this systematic group got their name due to the shape of the body. The cross section of flatworms resembles a sheet or ribbon. These animals are characterized by bilateral symmetry and well-formed organ systems. The musculoskeletal system is represented by a skin-muscular sac, which consists of an integumentary epithelium and several layers of muscles. The excretory system consists of thin tubules that open outwards with pores.
The vast majority of flatworms- hermaphrodites, but some can reproduce vegetatively. In parasitic species, a change of hosts is observed in the life cycle - final and intermediate. The nervous system consists of central and peripheral parts. But flatworms do not have respiratory organs and carry out gas exchange through the entire surface of the body.
Habitat
Among these animals, there are both parasitic and free-living species, which determines the nutrition of flatworms. They can be found in the seas, fresh water, and very rarely on land in tropical forests.
Parasitic species live in the intestines and liver of many animals: cattle, pigs, dogs, cats and even sperm whales. Some dangerous species also live in the human body.
Features of the digestive system
The digestive system of flatworms is closed. It consists of the mouth opening and intestines. How are flatworms fed? Food particles enter through the mouth, are digested in the branched intestine, and the remains are also removed through the opening located at the front end of the body.
Eating flatworms, which lead a parasitic lifestyle, occurs at the expense of the host organism. In such species, the organs of the digestive system are completely absent. Already digested substances they absorb through the covers.
Eating flatworms
Worms that live in various bodies of water are predators. They attack small benthic animals and with the help of a special proboscissucking out their contents.
The nutrition of flatworms and roundworms is somewhat different, since the latter have a through-type digestive system. It looks like a tube with a mouth and anus, so their metabolism is more intense. Free-living terrestrial flatworms feed on insect larvae that live in the damp forest floor.
Ciliary worms
Representatives of this class of animals live in water. In this environment, epithelial cells secrete a special secret that helps to keep small bottom animals - crustaceans, hydras, various larvae. The feeding of flatworms of this class is very unusual.
For example, in milky-white planaria, the mouth opening is located in the middle of the body on its ventral side. The worm crawls on the victim, thus holding it. Further, a proboscis protrudes through the mouth opening, with the help of which the planaria sucks the liquid contents from the body of the prey.
The Flukes
What do flatworms, which are parasites, eat? Let's consider this question on the example of the fluke class. They got their name due to the presence of suckers. Usually there are two of them: oral and abdominal. With their help, parasites attach to the internal organs of the host's body.
These worms go through a rather complicated life cycle in the course of their development. For example, the eggs of the liver fluke, first, together with the undigested food residues of a largecattle enter the water, and from there - into the body of mollusks, where tailed larvae develop from them, which again enter the water. Settling on plants, they turn into cysts. Cattle, which is the definitive host of the parasite, become infected when they drink water or eat grass. In his body, the cyst begins to grow and develop into an adult, the size of which reaches 3 cm.
It is at this stage that the worm feeds. At the bottom of the first sucker is a mouth opening that opens into the intestines. The digestive system looks like a bag or two channels that end blindly. Since these helminths do not have a body cavity and a circulatory system, the gastrointestinal tract also performs the function of supplying the whole organism with various substances. Flukes feed on blood, mucus and epithelial cells. The metabolic products of helminths are excreted through the mouth, while poisoning the body of the final host.
Tapeworms
Representatives of this class are characterized by the complete absence of the digestive system. This trait is related to their lifestyle. Special attachment organs are located on the head of tapeworms. They can serve as suckers, hooks or proboscis. With their help, parasites attach to the walls of the small intestine. Already partially digested substances they absorb the entire surface of the body, so they do not need the organs of the digestive system.
Tapeworms pose a serious danger to the person who is to themboth intermediate and definitive host. Absorbing large amounts of nutrients and vitamins, the parasite grows rapidly, sometimes reaching gigantic proportions. For example, bovine and pork tapeworms grow up to 10 meters. Feeding on substances intended for humans, parasites quickly deplete his body. At the same time, the host is also poisoned by the metabolic products of worms. A person infected with helminths experiences weakness, dizziness, nausea, lack of appetite, and even loss of consciousness.
So, what flatworms eat depends on their habitat and way of life. These conditions also determine the structural features of their digestive system. This type of animal combines 3 classes: ciliary, tapeworms and flukes. The former are free-living predators that prey on smaller animals in water bodies. Flukes are parasites that attach themselves to internal organs and feed on food and tissues. Tapeworms lack a digestive system. These parasites live in the lumen of the small intestine of animals and humans, feeding on already digested food particles.
