White planaria (planarian) is found almost throughout the globe, except for areas with a cold climate. So, what is a white planaria, what are the features of the life of this helminth and is it dangerous for humans?

Type of worms of white planaria - (suborder Tricladida ) class of ciliated invertebrates. It got its name because of the special milky white color. It has an elongated shape and a two-sided symmetrical body.

The length of the helminth is from 1 to 3 cm, so it is considered the largest among its own kind. Adults and its eggs are quite resistant to sudden temperature changes, to chemical attack.

white planaria

According to zoologists, the white planaria belongs to fairly developed creatures of its level.

Among other representatives of the general genus, the following planarians can be named:

1. Brown.
2. Black.
3. Funeral.
4. Horned.
5. Angular.

The main feature of the milky white planaria is rebirth, that is, the regeneration of body parts that have been lost for some reason.

If you divide it lengthwise or across, it miraculously modifies into two separate individuals. These independent pieces in a few weeks begin to live their own full life.

The internal structure of the white planaria consists of:

The structure of the helminth has a number of individualities:

1. Pointed triangular head.
2. A pair of black eyes placed behind the outgrowths. The organs of vision are able to respond to the level of illumination.
3. A good sense of smell, which allows the worm to "smell" the victim and head towards it.
4. Short outgrowths (tentacles) on the sides of the head.
5. The presence of three germ layers: ectoderm, endoderm and mesoderm.
6. The planaria lacks a body cavity, so the internal organs of the white planaria are placed in an elastic parenchyma. Together with the ectoderm, it forms a skin-muscular sac that helps the worm to move smoothly.
7. Gastrointestinal tract with one opening.
8. Well developed muscular system. There are longitudinal and transverse muscle tissues, with the help of which the worm, if necessary, lengthens, decreases and moves.
9. In the nervous system of the white planaria there are ganglia - nerve nodes, which are often called the brain. Scientists claim that spontaneous electrophysiological oscillations occur in this two-lobed mass, as in higher organisms.

The internal structure of the white planaria is absolutely primitive:

1. Respiratory organs are absent. The uptake of oxygen and the removal of carbon dioxide is done by diffusion.
2. The excretory organs are made up of a large number of pore tubes and ciliary flame cells that help the body get rid of excess moisture. Waste products exit through the dorsal pores of the helminth.
3. A free-living animal, the white planaria moves with the help of small cilia that are located throughout its body.

The digestive system of the white planaria is represented by:

1. Mouth (located in the center of the lower body).
2. Pharynx.
3. Intestine (gastrovascular cavity).

Digestive system of white planaria

White planaria (pictured above) is able to attack other living creatures - small fish, mollusks, crustaceans, eggs. He does not disdain carrion, and if kept in captivity, he will not refuse white bread and algae. Such an extensive diet is due to the presence of a pharynx, which, when hunting for prey, extends from the body in the form of a proboscis. Further, the proboscis-pharynx penetrates under the body of the prey, which begins to collapse from the impact of a specific secret secreted by the pharynx.

The pharynx connects the oral and gastrovascular cavities. The digestive structure stretches throughout the body of the worm, thanks to which the necessary substances obtained from food reach all limbs. In the intestine there are a large number of tiny blindly closed processes. Through the surface of the body of the planaria, the dark contents of the intestine are clearly visible.

Reproduction features

Milky white planaria is a hermaphrodite, that is, one individual has both female and male genital organs.

Can reproduce in two ways:

1. Sexual.
2. By division.

However, for reproduction, a pair of worms is needed for the mutual exchange of seminal fluids. After fertilization, eggs are born, which are laid in secluded places. Eggs have strong shells, immune to minus and plus temperature changes. Reproduction by copulation for planarians is a more acceptable option, which increases their genetic level and improves survival.

Lost head regeneration

During asexual (fission) reproduction, the worm tears off its own tip of the tail, then each part is revived by regeneration. Pluripotent stem cells divide, resulting in two worms.

What diseases causes

Fluvermal

but the use of febendazole in the form of a suspension gives the best result than a self-prepared solution. This is because the powder is difficult to dissolve in water. Next, a thorough cleaning of the aquarium and a change of water is carried out.

To get rid of the worm, you can use other drugs that have the active substance febendazole:

1. Flubendazole.
2. Fluvermal.
3. Panakur.
4. Flubenol.

After applying a saline, sodium or acetic solution, all items in the aquarium are washed in clean water, and the water in the aquarium itself must be changed.

Prevention measures

Photo white planaria

For white planaria warnings in home ponds, the following must be observed:

In order to avoid the appearance of white planaria in an aquarium or a home pond, it is necessary to follow all preventive measures that will help prevent the appearance of unwanted inhabitants that show aggression against your freshwater pets.

In contact with

(1-2 cm in length). Milky white planaria belongs to the class Ciliary worms.

External structure

The body of the milky-white planaria is thin and elongated, it is strongly flattened from top to bottom (in the dorsal-abdominal direction). In this way, a large body surface area (compared to volume) is achieved through which gas exchange takes place. The back end of the body of the planaria is pointed, and the front end is expanded, and departs from it in both directions along a short ledge - these are the organs of touch. Two black eyes are also placed here. If you look closely, you can see that the right half of the planaria looks like a mirror image of the left.

Such symmetry, in contrast to the radial symmetry of intestinal cavities, is called bilateral. It is characteristic of most multicellular animals and arose in connection with the development of active movement.

Three-layer structure

Unlike coelenterates, flatworms, including planaria, are not two-layered, but three-layered animals (Fig. 43). During embryonic development, an intermediate layer appears between the ectoderm and endoderm - the mesoderm.

The emergence of the mesoderm is very important for multicellular animals. The mesoderm is involved in the formation of various organs and organ systems. Examples of such systems are muscular, sexual (reproductive), and in most three-layer organisms, also excretory.

The bulk of the mesoderm of flatworms fills the space between the ectoderm and endoderm and is a lining tissue that provides support and protection to the internal organs.

Integuments and muscles

The body of the milky-white planarian is covered with an epithelium consisting of cylindrical cells.

Epithelial cells have cilia. Between the epithelial cells are glandular cells that secrete mucus. In the epithelium there are also special formations that are ejected, like stinging cells of the coelenterates, at the moment of capturing food and, swelling in water, envelop the prey, thereby contributing to its retention.

Under the ciliary epithelium there are several layers of muscle cells: outer (circular muscles), intermediate (oblique muscles) and inner (longitudinal muscles) (Fig. 43). There are also dorsal-abdominal muscle bundles.

Unlike coelenterates, planarian muscles are formed not by processes of epithelial-muscular cells, but by independent muscle fibers. Such a complex musculature allows the planaria to make a variety of and fairly fast movements.

Digestive system

Milky white planaria feeds on very small crustaceans (Fig. 42), worms and the remains of large aquatic animals. To capture food, the planaria settles over the prey and, thanks to the contraction of the muscles of the body, presses against it, then swallows the victim with a retractable pharynx with a mouth opening at the end.

asexual reproduction occurs by transverse division of the planarian body in half. The tear line runs behind the pharynx. Each half then regenerates the missing body parts.

sexual reproduction planarian complex.

In front of the body are two oval bodies - the ovaries, and on the sides of the body are scattered numerous vesicles - the testes. Eggs develop in the ovaries, and spermatozoa develop in the testes. Male and female sex cells must meet. But before they meet, complex processes take place in which two hermaphrodite planarians participate.

Fertilization is preceded by copulation (copulation): two planarians touch each other with the ventral side of the body and introduce the mutually copulatory organ into the partner's copulatory sac, filling it with sperm - the sexual fluid with spermatozoa. After that, the planarians diverge. In each of them, the resulting sperm rises through the oviducts to the seminal receptacles, where fertilization takes place. Fertilized eggs, as they move down the oviducts, are surrounded by yolk cells - reserve nutrients and a shell. In the genital cloaca, from several fertilized eggs, surrounded by a large number of yolk cells, a cocoon is formed, which is brought out. After a few weeks, small planaria hatch from the eggs in the cocoon.

On this page, material on the topics:

• Milk planaria nervous system

• Select an animal with ray symmetry

• Planaria breeding

• The reproductive system of planarian organs and describe the features of their structure

• Message about white planaria

Questions about this item:

• White planaria is a creature that belongs to the ciliary worms. Lives mainly in fresh water. White planarians try to avoid daylight, so they often hide behind pebbles and under plants. These are predators whose food is small aquatic animals - crustaceans, protozoa, insect larvae, fish eggs. The structure of a planarian is quite primitive, but this worm has an amazing ability to regenerate.

  Among other members of the genus:

  • black planaria;
  • brown;
  • mourning;
  • angle-headed planaria;
  • horned.

  The white planaria, so named because of its milky pink color, is the largest among the worms, which are united by one taxonomy. It reaches a length of 3 cm, in its anatomy it is similar to other flatworms. Distinctive features of its structure are an elongated shape and bilateral symmetry of the body.

  The white planaria (a type of flatworm) and other representatives of this genus have an extraordinary ability - the regeneration of lost body parts. For example, a planarian divided across or along is reborn into two separate individuals. Tiny pieces of the worm become a full-fledged organism in just a few weeks.

  New tissues can grow thanks to pluripotent stem cells called neoblasts. These are the only worm cells that can actively divide. During the regeneration process, the existing tissue is rearranged to restore the symmetry, proportions, and organs of the white planaria.

  Structural features

  The white planaria has three germ layers: ectoderm, mesoderm and endoderm. These are intestinal worms and they are actually deprived of body cavities. But there is a gastrointestinal tract with one hole.

  This flatworm has a head shaped like a pike or a triangle. In the external structure of the planaria, tactile organs can be distinguished - these are short and tentacle-like outgrowths on the sides of the head.

  Worms also have other sense organs - two black eyes located behind the outgrowths. They react to light levels. In addition, they have a developed sense of smell, which helps them to smell the prey, after which the worm quickly moves towards it.

  The nervous system of the white planaria includes ganglia. This bilobed mass of tissue is sometimes even referred to as the brain. Scientists have demonstrated that spontaneous electrophysiological oscillations occur here, as in more developed animals.

  From the ganglia there are two nerve cords, they extend to the caudal part of the worm. There are many transverse nerves associated with cords. This makes the organ system of the white planaria look like a ladder. This neural organization helps the worm to respond in a coordinated manner.

  

  The internal structure of the white planaria is generally very simple. These ciliary worms are deprived of respiratory organs, they absorb oxygen and release carbon dioxide through diffusion. The excretory system consists of numerous tubules with pores and cells with a ciliary flame. The latter also serve to remove unnecessary fluid from the body. Waste excretion is carried out through the pores on the dorsal surface of the worm.

  Planaria is a free-living animal that attacks other creatures - from other worms and crustaceans to small fish and snails. She can eat carrion, and in captivity - even white bread.

  Such a variety in food is due to the fact that worms do not need to swallow their prey whole. In the structure of the white planaria there is one interesting organ - the pharynx, which can be extended from the body cavity. It penetrates under the covers of the prey, after which the tissues of the victim are destroyed under the action of a secret that is secreted by the throat of the worm.

  The digestive system of a planaria includes the following organs:

  • Oral cavity.
  • Pharynx.
  • Gastrovascular cavity (intestine).

  The digestive system of ciliary worms, most of which are carnivorous, allows them to digest food with the help of enzymes. They are secreted from the mouth, which is located in the center of the lower body. These enzymes trigger external digestion.

  

  The pharynx serves to connect the mouth and the gastrovascular cavity. This structure extends throughout the body, allowing the right substances from food to reach all the limbs. The intestine is supplied with many small blindly closed branches. Its dark contents can even be seen through the integument of the body.

  When a dairy planaria feeds, it sucks the food in with its muscular mouth. Food passes through the pharynx into the intestines, where it is absorbed by the cells that line it. The food is then distributed to the rest of the body.

  reproduction

  The white planaria is a hermaphrodite, the worm has male and female genital organs. But in any case, two individuals are needed to reproduce. One passes on its secretions to the other, receiving and giving seminal fluid. As a result of fertilization, eggs are formed inside the body. For masonry, worms choose safe and protected places. Eggs are covered with a dense shell, resistant to both very low and high temperatures.

  Sexual reproduction of planaria is the preferred option. This improves survival by increasing the level of genetic diversity.

  In asexual reproduction, the dairy planaria tears off its tail end. Each half then regains the lost parts through regeneration. The neoblasts divide and differentiate, resulting in two worms.

  Possible danger

  They pose no threat to humans. But planarians in an aquarium can lead to a significant reduction in the biological diversity in it. These predators will quickly destroy small crustaceans, shrimps and even fish. They appear as a result of improper care of the aquarium. If the planaria unites with another pest - the hydra, together they can cause serious damage.

  • Feed the inhabitants in moderation. Food that has not been eaten in time is the best food for any aquarium pest.
  • Clean your aquarium thoroughly and regularly. Don't forget about soil treatment.
  • Be careful and watch for the possible appearance of pests. They multiply very quickly and without appropriate measures will quickly fill the aquarium.

  Dairy planaria lives in fresh water and is not dangerous to humans. However, the aquarium owner needs to be careful. The lifestyle of the white planaria is very active - it quickly breeds and develops. As a result, this worm can greatly harm the biological diversity of the aquarium.

  A flatworm about 2 cm long - white planaria - can be found at the bottom of the pond and on the leaves of aquatic plants. It slides along the bottom with the help of a barely noticeable wave-like contraction of the muscles of the body. This is the main "achievement" of flatworms.

  The body has bilateral symmetry. This is due to a mobile lifestyle, the allocation of the front end of the body. Through the longitudinal axis of the body, you can build only one plane of symmetry.

  Like coelenterates, worms distinguish between top and bottom. Below is the bottom, the source of food, and above all the dangers. But when moving along the bottom, differences also arise between the anterior and posterior ends of the body. Moving forward, the animal is looking for food, and behind the food has already been eaten. It is much more convenient when the mouth and sense organs are at the front end of the body. Therefore, only one plane of symmetry can be drawn through the long axis of the worm, which divides it into equal halves. So, as a result of movement, the body of animals became bilaterally symmetrical.

  

  Compared with coelenterates, flatworms are the first three-layer animals: in addition to the ectoderm and endoderm, they have developed mesoderm. They do not have a body cavity, and the spaces between the organs are filled with connective tissue. There is no anus in the digestive system, and undigested residues are expelled through the mouth. Flatworms are bisexual animals, or hermaphrodites.

  External structure

  Skin covering

  Outside, the body of free-living flatworms is covered with elongated cells with cilia. The covers of their body can be painted in different colors - green, yellow, pink, brown, black, red, purple, gray.

  

  Internal structure

  Most flatworms have acquired a closed intestine from the ectoderm. This allowed them to reach large sizes and feed on large prey.

  The difference is that in a flat body between the ento- and ectoderm, a third germ layer, the mesoderm, has developed. Part of its cells became the elastic filler of the body - the parenchyma, while others turned into muscle fibers. So the mesoderm together with the ectoderm formed a skin-muscular sac. It was he who provided the typical crawling method for worms.

  

  The main features of the high organization of the white planaria:

  

  muscles

  Deeper than the ciliary epithelium lie muscle fibers located across the body of the worm. With the contraction of the transverse muscles, the worm becomes narrower and longer. Under the transverse are longitudinal muscle fibers connecting the dorsal and ventral sides of the body.

  

  Under the transverse and longitudinal muscle fibers is a loose mass of small cells - the parenchyma. It fills the gaps between the internal organs. Muscles and parenchyma are formed from the third (intermediate) germinal layer of cells.

  Digestive system

  Planaria is a predator, it attacks small animals, such as crustaceans and worms. Special secretions of some epithelial cells that swell in water help it to hold prey. Planaria clings to the caught victim, and then swallows it with the help of a retractable pharynx.

  Most free-living flatworms have a branched intestine that opens outward through the mouth opening.

  

  The intestinal wall is made up of a single layer of cells that capture ingested food particles and digest them. Nutrients then penetrate into all other cells of the body, and undigested food remains from the cells into the intestinal cavity and are removed out through the mouth.

  

  Digestion of food also occurs in the intestinal cavity under the influence of digestive juices secreted by the glandular cells of the intestine.

  Circulatory system

  Missing.

  Breath

  Free-living flatworms breathe oxygen dissolved in water. Oxygen enters the body and carbon dioxide is removed through the skin.

  

  The flat body of a planaria with a large surface contributes to better gas exchange in the body.

  excretory system

  The organs of excretion are branched tubes (tubules) penetrating the body of the worm.

  

  They begin in the parenchyma as stellate cells. Each cell has a bunch of long cilia that constantly fluctuate. They are called "flame cells" because the movement of the cilia resembles the tongue of an oscillating flame. Vibration of the cilia creates a flow of fluid in the tubules.

  

  The tubules merge into two longitudinal canals, which open outward through several openings (pores) on the dorsal side of the body. The fluid that is excreted from the body consists of an aqueous solution of harmful products formed in the body of the planarian.

  Nervous system

  The nervous system of free-living flatworms consists of clusters of nerve cells - paired head ganglions, nerve trunks, and numerous nerve branches. Numerous organs depart from the nerve trunks to all organs.

  

  sense organs

  The organs of touch are well developed - sensitive cells located on the surface of the body. Special organs of touch - paired tentacles are located at the front end of the body. Next to them are the eyes, with their help the planarian distinguishes the level of illumination. There is an organ of balance.

  sexual reproduction

  Planarians reproduce mainly sexually. They are hermaphrodites: their reproductive system is represented by both female and male genital organs in one organism. Thus, the same individual has male reproductive organs (testes) and female reproductive organs (ovaries).

  reproductive system

  In the parenchyma there are numerous vesicles - testes. From them there are tubular vas deferens to the copulatory organ. These are all parts of the male reproductive system.

  

  The female reproductive system consists of paired ovaries, from which tubules, the oviducts, extend to the copulatory sac.

  Fertilization

  Fertilization in planaria is internal. During copulation, two planarians touch each other with their ventral sides. The male germ cells of one animal enter the female reproductive system of another animal. After that, the animals disperse. The spermatozoa fertilize the eggs. The resulting zygotes move down the oviducts. As they move, they are first surrounded by a supply of nutrients, and then by a shell. Eggs (brown in color), packed in a cocoon (slightly larger than a pinhead), are brought out.

  

  Such cocoons are attached to underwater objects on a special stalk. After a few weeks, small planarians emerge from them.

  asexual reproduction

  Asexual reproduction of planarians occurs due to the transverse division of the worm in half. Then a whole planaria is restored from each half.

  Appearance of the worm

  a brief description of

  The creature is a representative of the worm-like class, the length of its body does not exceed two centimeters. A typical habitat for planarians is the bottom of water bodies, where they get food. Representatives of the intestinal cavities can distinguish conditional indicators: top - danger, bottom - food and comfort.

  The movements of the planaria, through which it moves over the stones and plants at the bottom, are difficult to discern with the naked eye, they are barely noticeable undulating contractions of muscle tissue. Through the axis of the worm, you can draw a conditional line that divides its body into two halves. This provides the simplest full-fledged existence in the conditions of the surrounding world.

  The diet of dairy planaria includes crustaceans, tiny fish, eggs, as well as various particles of organic matter. The worm belongs to the order of predatory representatives of the animal world. The structure of his body does not provide for an anus, undigested food residues are removed naturally through the mouth.

  

  Crustaceans - planarian food

  Important! All the facts listed above characterize only flatworms.

  Variety of species

  As other representatives of the extensive planarian genus:

  • black;
  • brown;
  • angle-headed;
  • horned;
  • mourning.

  

  Worms classification

  Each species got its name due to external differences. But an amazing regenerative ability is inherent in all representatives of the planarian genus. These worms can completely restore lost or removed tissues and internal organs in a short time. Individual particles of the protozoan can develop into viable adults within a few weeks.

  Structure

  The anatomy of a freshwater planaria is simplistic. The length of the body varies from one to two centimeters, and the thickness does not exceed 5 mm. The simplest has a biopolar body, that is, both longitudinal halves of its body are symmetrical. This primitive creature has some kind of head, equipped with eyes and a pair of tactile tentacles.

  The body of the worm has a light milky color. Its entire surface is covered with tiny cilia, which allow it to move freely in its usual habitats.

  

  Planaria in section

  The structure of the worm is as follows:

  • The digestive system consists of a retractable pharynx and an intestine lined with a layer of cells. Remaining nutrients are removed from the organism of the protozoan through the mouth opening.
  • The nervous system is represented by an accumulation of bundles of cells, where the main ones are paired nodes located in the head region.
  • The properties of the excretory system are possessed by the entire surface of the body of a primitive being, which is permeated with excretory tubules.
  • There are transverse and longitudinal muscle fibers that allow it to lengthen, contract and move.
  • The sense organs are the tactile system and the eyes.
  • The circulatory system is absent.

  

  The structure of individual systems

  The body of the worm is formed from the skin-muscle cover and is permeated with tubular glands that secrete mucus, which facilitate the movement of the protozoan in space.

  Important! Worms living in natural conditions have the ability to secrete a bitter, caustic mucus that protects them from the encroachments of various predators. When keeping planarians in artificial conditions, this ability is lost.

  Due to the specifics of life, protozoa do not need a host organism for growth and development.

  These protozoa are predators and prey on other small creatures. They also feed on carrion, and in artificial conditions - bread and algae. Such impartiality is due to the peculiarities of the structure of the digestive system.

  Digestion is carried out with the help of enzymes that are secreted from the mouth of the protozoan. Planaria absorbs food that enters the intestines, distributing further throughout the body, and providing nutrients to all parts of the body.

  Reproduction features

  According to the anatomical structure of the planaria, it belongs to hermaphrodites. The simplest has a set of both female and male genital organs. But despite this feature, 2 mature individuals are required for reproduction.

  

  The reproductive system of a planarian

  Worms exchange male and female secretions, and at the end of the act of love, numerous eggs are formed in their body. As a rule, laying is carried out in safe places. Eggs can remain viable even when exposed to excessively high or low temperatures.

  In the absence of a partner, planarians can also reproduce in an unpaired way. To do this, an adult individual tears off its own tail, which is subsequently regenerated, forming a new primitive creature.

  Important! The possibility of unpaired reproduction exists, but planarians reproduce mainly sexually, since through the use of this method, the genetics of future offspring improves.

  Risks

  For humans and large animals, white planarians do not pose a danger, since they do not need a final or intermediate host for growth, reproduction and development. However, the appearance of planarians in an aquarium is potentially dangerous for its inhabitants and especially for small fish. The simplest can eat both the direct inhabitants of the aquarium and the food intended for them.

  

  Medications are used to get rid of the worm

  The main reason for the appearance of white planarians in freshwater aquariums is unsanitary conditions. The constant presence of uneaten food particles and other contaminants is ideal conditions for primitive pests that can multiply at an incredible rate, causing damage to the flora and fauna of the aquarium.

  The theme of the video is planaria: