Type of Gut: general characteristic

One of the first groups of multicellular animals is the type of the intestinal. The 7th grade, which includes a course of zoology, examines in detail all the features of the structure of these amazing creatures. Let's once again remember what they are.

Type of the genitourinary: biology

The name of a systematic unit these animals received due to the same name structure. It is called the intestinal cavity, and it has all the representatives of the type: both polyps, leading an attached lifestyle, and actively moving jellyfish. Characteristic type of coelenterates also is the presence of specialized cells. But despite this progressive feature of the structure, the body of these animals does not form real tissues.

Habitat and dimensions

These first true multicellular animals can be found in fresh and salt water bodies of various climatic zones. Type of the intestinal (the 7th grade of the general education school studies this subject in sufficient detail) is represented by small individuals with a diameter of several millimeters, and jellyfish-giants with a tentacle length of up to 15 meters. Therefore, the nature of the reservoir, where they live, can be different. Thus, small freshwater hydra inhabit small puddles, and coral polyps form huge colonies in the tropical seas.

Type of Gut: general characteristic

The body of all coelenterates consists of cells of several types, each of which performs a certain function, like the organs of more complex animals.

The main characteristic of coelenterates is the presence of stinging cells. They consist of a capsule in which a thread with a sharp end is twisted. A sensitive hair is located on top of the cell. When he touches the victim's body, he unwinds and bites into it with force. As a result, it has a paralyzing effect. Further, with the help of tentacles, representatives of this type place the victim in the intestinal cavity. And here begins the process of splitting organic substances. And it helps to carry out digestive and glandular cells.

Type of the intestinal cavity is characterized by a high degree of regeneration. Scientists have proven that the freshwater hydra can completely restore the body from the 1/200 part. And perhaps this is due to the presence of intermediate cells. They actively share, giving rise to all other types. Capable of coelenterates and sexual reproduction due to the fusion of eggs and spermatozoa.

Nerve cells are scattered all over the body, realizing the relationship of the organism with the environment and integrating it into a single whole. So, very interesting is the movement of one of the representatives of coelenterates - hydra. Thanks to the activity of the skin-muscle cells, she, like an acrobat, moves from head to sole, making a real somersault.

Processes of life of coelenterates

Type of the intestinal is characterized by more complex physiology in comparison with its predecessors - the simplest animals and sponges. Although there are common signs. For example, gas exchange still occurs through coverlets, and specialized structures for this are absent.

Due to the presence of skin-muscle cells, jellyfish are capable of reactive movement. At the same time, their bell is shortened, the water is pushed out with force, causing a backward thrust.

All coelenterates are predatory animals. With the help of tentacles, extraction through the mouth opens into the body. The effectiveness of the cleavage process is proved by the existence of two types of digestion simultaneously: cavitary and cellular.

Coelenterates are characterized by the presence of a response of their body to stimulation - reflexes. They arise in response to mechanical or chemical effects from the environment. And jellyfish have special sensitive formations, ensuring the balance of the body and the perception of light.

Life cycle

The type of the intestinal canal is also characterized by the fact that in many of its species the alternation of generations is observed in the life cycle. For example, the aurelia polyp propagates by an exclusive asexual pathway by means of budding. Over time, the body of one of them is divided by transverse constrictions. As a result, small jellyfish appear. Visually they resemble a stack of plates. In turn, they break away from above and move on to an independent and mobile way of life.

The alternation of sexual and asexual generations in the life cycle of coelenterates facilitates a rapid increase in their numbers and a more efficient resettlement.

Includes the type of Guttural Cavity classes, polyps which do not split off. They form colonies of bizarre forms. It's coral polyps. There is no alternation of generations between the freshwater hydra. They reproduce in the summer by budding, and in the autumn they pass to sexual reproduction, after which they perish. Fertilized ovules winter at the bottom of water bodies. And in the spring of them young hydras develop.

Variety of coelenterates

Type Intestinal in nature is represented by two life forms: polyps and jellyfish. One of the most interesting representatives of the first group is actinia. It is the inhabitant of the warm tropical seas, which, due to its bright color, looks like a fantastic flower. Hence the second name of sea anemones - sea anemones. Among them there are predators and filterers. And some species of actinia can enter into mutually beneficial cohabitation with hermit crabs.

Polyp has the ability to move around and feed on the remains of organic food of arthropods. And the cancer is safely protected by the stinging cells of anemia. It is interesting that, changing the shell from time to time, he transplants polyp. Cancer strokes the actinium of the claws, as a result of which it independently crawls into a new dwelling.

And colonies of coral polyps form huge clusters. For example, the Great Barrier Reef stretches along the coast of Australia for a distance of about 2 thousand km.

The importance of coelenterates in nature and human life

Many coelenterates can be dangerous for animals and humans. The action of their stinging cells causes burns. Their consequences for a person can be convulsions, headache, dysfunctions of the heart and respiratory organs. If you do not help in time, a fatal outcome is possible.

Polyps and jellyfish are an important link in the feeding chain of aquatic inhabitants. Corals in many countries are used for making jewelry, souvenirs and building materials.

So, the type of the intestinal, whose general characteristic was examined by us, is represented by two life forms. They are polyps and jellyfish. These animals are characterized by radiation symmetry, the presence of specialized cells and the alternation of generations in the life cycle.