The life and structure of the planaria

White planaria is a primitive creature that can live not only in fresh water bodies, but also in salt water. The presented view of a flat worm does not harm either animal or human. However, this creature also does not belong to the category of beneficial organisms. What is a planar? The features of the structure of such a flat worm are discussed below.

What is a planar?

In fresh water, at the very bottom, under pebbles and driftwood, you can find a miniature creature in the form of a flat white worm with a translucent structure of the body. Scientists refer such organisms to the category of harmless parasites.

Visually in the planaria, both body surfaces are symmetrical and reflect each other. Despite the negative reputation of parasitic flatworms, such an animal poses no danger to other living organisms. Specialists refer the planaria to predators that feed on simple organic compounds, small crustaceans, fish fry.

External structure of the planaria

Planaria has a bipolar body. The right side of the creature is mirrored to the left. The conditional line separates the entire body. This external structure of the white planaria allows it to live in conditions not only of water bodies, but also of land.

The length of the body of a flat worm is not more than two centimeters. The thickness can be up to 5 mm. In the anterior part of the body, the planar has a special extension, where tactile tentacles are located. The back of the worm is narrowed and somewhat pointed at the end. On the entire surface of the body are the so-called cilia, the movement of which facilitates the movement of the creature in space.

Internal structure of the planaria

Planaria has the following internal structure:

1. The muscle bag is a specific fiber that runs across the entire body. When they are cut, the flat worm lengthens. The back and abdominal cavity of the animal are connected by longitudinal muscle fibers.
2. The sense organs are tactile cells, paired tentacles, an organ of balance, primitive eyes, capable of responding to light.
3. The nervous system - nodes in the form of a cluster of receptors, nerve branches.
4. Excretory system - branched tubules that permeate the entire body of the creature.
5. The digestive system is a special epithelial cell that enables a flat worm to capture prey. For the absorption of food answers a retractable gulp. The food is digested in a single-layered intestine. The waste is discharged to the outside, passing back through the mouth opening.

How does the planar move?

So we looked at the structure of the planaria. Now let's find out how this primitive animal moves.

The planetarium creeps under the water, moving on solid objects. The flat worm moves extremely smoothly, evenly and slowly. Looking at the planaria in the aquarium, you might think that the animal swims in the water column without much effort. In fact, on the body of the worm is located a lot of imperceptible to the human eye moving cilia.

Among other things, the planaria allocate a specific mucus, through which the tracks are laid on objects for multiple movements. Small planarians are able to swim, performing oar-shaped movements with cilia.

Lifestyle

Planariae are active at night. A flat worm hides under rocks, driftwood, underwater foliage.

The creature carries a danger to the mollusks. Planariae enter their respiratory system, which leads to the gradual death of the mollusk.

In the process of life, the planaria produce mucus, which swells in the water, forming a kind of cobweb. Due to this the creature envelops its potential prey.

Development

Primitive being, despite its relation to the category of parasitic flatworms, is completely independent of other organisms. For the development of the planaria, intermediate or final hosts are not required. On the contrary, close relatives of this creature, such as hawks and flukes, parasitize in the body of animals and humans, without having the opportunity for development and reproduction without this.

Reproduction

Planaria belongs to the hermaphrodite category. For the creature, several ways of multiplying simultaneously are characteristic:

1. Division - at the onset of the period of sexual activity, the body of a flat worm stratifies. The adult individual gradually divides into several parts. After passing some time in both halves, the mechanisms necessary for normal vital activity are formed. As a result of such simple manipulations, one parasite is transformed into several full individuals.
2. Sexual mode - mature planaria lays eggs on a fertile substrate. For fertilization of the masonry, flat worms touch the bodies for a few moments. Thus, as a result of the union of female and male germ cells, a zygote is formed. A cocoon is formed from it, where the eggs are stored until their full maturation. Usually, the appearance of numerous young specimens of the planaria takes from two to three weeks.

Interesting Facts

The simple construction of the planaria contributes to its highest survivability. The body of a flat worm possesses regenerative abilities. Even after separation of the head from the body, a new one gradually grows in its place. If you divide the adult individual into separate pieces, eventually the original organism can recover from them. This feature contributes to the survival of the planaria in the most unfavorable conditions.

The specific structure of the planaria gives it the ability to withstand the aggressive environmental factors. For example, with a lack of oxygen for breathing, an increase in temperature, the creature passes into a low-active form. In the future, the planarians are able to disintegrate into separate pieces. The latter are regenerated under favorable conditions.

Planaria are extremely sensitive to potential prey. When there is a lack of food in the habitat, flat worms feel nutrients at a considerable distance. Sensing the food, the colonies of the planarians get out of their own shelters and move by hundreds in the pond to the places where the prey is.

Contents of planaria in aquariums

Despite the gentle structure of the planaria, the softness of the outer covers, such a creature can be kept in an aquarium. And a flat worm is not able to harm other inhabitants of an artificial reservoir. As already noted above, the planaria allocates in the process of vital activity an abundance of rather unpleasant mucus. Therefore, even large fish such creatures do not have to taste. The smaller predators who decided to attack the planaria are enveloped in a sticky substance and lose their motion, remaining in a paralyzed state for a while.

Planaria in the aquarium does not need a special feed. The creature feeds on the livelihoods of other animals, decaying remnants, particles of dead plants.

Finally

So we examined the internal, as well as the external structure of flatworms. Because of its way of life, the planetarium is a harmless parasite. Throughout life, such a flat worm does not require a master. Unlike their parasitic brethren, the presented creature is able to independently procure subsistence in natural habitats.