type of flat worms composed of non-parasitic and parasitic forms.In this free-living organisms are combined in one class, and those who live at the expense of other organisms, - six.Representatives of Class Ciliated (Planaria, turbellarians) live in water bodies, most often by predators.
Parasitic flatworms live in the body of animals and humans.These organisms are so well adapted to the conditions of life, t. To. Have suckers, which are attached to the walls of the internal organs of the host, and segmented body with an ever-increasing number of segments.They are characterized by the absence of the digestive system (except for class Flukes), nutrients are absorbed through special outgrowths of the body;anaerobic respiration (they breathe in almost oxygen-free environment), as well as proliferation (they are hermaphrodites).
All of these features allow this organism to settle permanently in the host body and be at his expense.These helminths include: liver fluke, remenets, cat fluke, pork tapeworm, Echinococcus and others. To catch them the person can, if eats raw or poorly treated cattle meat, pork and fish.
type of flat worms combines organisms that have similar features, both external and internal structure.They represent bespolostnoy animals have an elongated, flattened body from top to bottom, ie. E. It is flat or nearly flat.Also, it is their first appearance bilateral symmetry in the process of ontogenesis laid three germ layers - ecto, meso and endoderm - of which later formed the internal organs.Type Flatworms also characterizes the presence of skin-muscular sac, which represents the totality of the epithelium and placed underneath the muscle fibers.This allows them to "worm-like" move.
digestive system in free form has a primitive structure and consists of a foregut, or pharynx, midgut, which ends blindly.In this system of helminths reduced.
nervous system flatworms presented paired cerebral ganglia and nerve trunks, which extend from a ring and connected jumpers.Strong development are two longitudinal ventral trunk.
circulatory and respiratory systems do not.Breathe representatives of the class ciliated epithelium, which covered their bodies outside.
Government allocation - protonephridia.They consist of a system of tubules that end stellate cells with cilia.Removal of metabolic products in the environment occurs through special excretory opening.
hermaphroditic reproductive system and often is a system of ducts, which are needed for elimination of sexual products, and copulatory organ for internal fertilization.
Thus, the type of flat worms - this is basically parasitic forms (worms), who were able to adapt and adjust to their way of life.
