freshwater hydra- extremely unwanted settlers in the aquarium where they are kept shrimps. Unfavourable conditions may cause hydra breeding, A hydra regeneration from the smallest remains of her body makes her almost immortal and indestructible. But still, there are effective methods fighting hydra.

What is a hydra?

Hydra(hydra) - freshwater polyp, ranging in size from 1 to 20 mm. Its body is a stem-leg, with which it attaches to any surfaces in the aquarium: glass, soil, snags, plants, and even snail egg laying. Inside the body of the hydra - the main organ that makes up its essence - the stomach. Why essence? Because her womb is insatiable. The long tentacles crowning the body of the hydra are in constant motion, capturing numerous small, sometimes invisible to the eye, living creatures from the water, bringing it to the mouth, which ends the body of the hydra.

In addition to the insatiable belly in the hydra, her ability to recover is frightening. Like , she can recreate herself from any piece of her body. For example, hydra can regenerate from cells left after rubbing it through mill gas (such a finely porous mesh). So rubbing it on the walls of the aquarium is useless.

The most common types of hydras in domestic reservoirs and aquariums:

- common hydra(Hydra vulgaris) - the body expands in the direction from the sole to the tentacles, which are twice as long as the body;

- hydra thin(Hydra attennata) - the body is thin, of uniform thickness, the tentacles are slightly longer than the body;

- hydra longstemmed(Hydra oligactis, Pelmatohydra) - the body is in the form of a long stem, and the tentacles exceed the body length by 2-5 times;

- hydra green(Hydra viridissima, Chlorohydra) is a small hydra with short tentacles, whose body color is provided by unicellular chlorella algae living in symbiosis with it (that is, inside it).

Hydra breed by budding (asexual variant) or by fertilization of an egg by a spermatozoon, as a result of which an “egg” is formed in the body of the hydra, which, after the death of an adult, waits in the wings in the ground or moss.

At all hydra - amazing creature. And if it were not for the obvious threat on her part to the small inhabitants of the aquarium, she could be admired. So, for example, scientists have been studying hydra for a long time, and new discoveries not only amaze them, but also make an invaluable contribution to the development of new medicines for humans. Thus, the hydramacin-1 protein was found in the body of the hydra, which has a wide spectrum of action against gram-positive and gram-negative pathogenic bacteria.

What does hydra eat?

Hydra hunts for small invertebrates: cyclops, daphnia, oligochaetes, rotifers, trematode larvae. In her death-bearing "paws" can please fish fry or young shrimp. The body and tentacles of the hydra are covered stinging cells, on the surface of which there is a sensitive hair. When it is irritated by a passing victim, a stinging thread is thrown out of the stinging cells, entangling the victim, piercing into it and letting out poison. Maybe hydra sting a snail crawling by or a shrimp swimming past. The ejection of the thread and the launch of the poison occur instantly and take about 3 ms in time. I myself have repeatedly seen how a shrimp that accidentally landed in a hydra colony bounced off like scalded. Numerous "shots" and, accordingly, large doses of poison can adversely affect adult shrimp or snails.

Where does the hydra come from in the aquarium?

There are many ways to bring hydra into an aquarium. With any object of natural origin, immersed in an aquarium, you can host this "infection". You will not even be able to establish the very fact of introducing eggs or microscopic hydras (remember, at the beginning of the article, their size is from 1 mm) with soil, snags, plants, live food, or even milligrams of water in which shrimp, snails or fish were purchased. Even with the apparent absence of hydras in the aquarium, they can be detected by examining any section of driftwood or stone under a microscope.

The impetus for their rapid reproduction, in fact, when hydra become visible to the aquarist, there is an overabundance of organic matter in the aquarium water. Personally, I found them in my aquarium after overfeeding. Then the wall closest to the lamp (I don’t have fluorescent lamps, but a table lamp) was covered with a “carpet” of hydras, which in appearance belong to the “thin hydra” species.

How to kill a hydra?

Hydra bothers many aquarists, or rather, the inhabitants of their aquariums. On the forum website the theme of "Hydra in the shrimp" has already been brought up three times. Having studied the reviews on the fight against hydra in the vast domestic and foreign Internet, I have collected the most effective (if you know more, supplement) methods for destroying hydras in an aquarium. After reading them, I think everyone will be able to choose the most appropriate method in his situation.

So. Of course, you always want to destroy uninvited guests without harming other inhabitants of the aquarium, primarily shrimp, fish and expensive snails. Therefore, salvation from hydras is mainly sought among biological methods.

Firstly, the hydra also has enemies that eat it. These are some fish: black molly, swordtails, from labyrinths - gourami, cockerels. They also feed on hydra and large pond snails. And if the first option is not suitable for a shrimp because of the threat from fish to shrimp, especially young ones, then the option with a snail is very suitable, only you need to take snails from a trusted source, and not from a reservoir in order to avoid introducing another infection into the aquarium.

Interestingly, Wikipedia refers to creatures capable of eating and digesting hydra tissue as turbellarians, which include planaria. Hydras and planarians, like "Tamara and I go together", really often find themselves in the aquarium at the same time. But for planarians to eat hydras, aquarists are silent about such observations, although I have read about this more.

Hydra also serve as the main diet for the cladoceran crustacean Anchistropus emarginatus. Although his other relatives - daphnia - hydras themselves are not averse to swallowing.

VIDEO: hydra tries to eat daphnia:

Used to fight the hydra and its love of light. It is noticed that hydra is located closer to the light source, moving to that place with steps from foot to head and from head to foot. Inventive aquarists came up with a peculiar hydra trap. A piece of glass is tightly leaning against the wall of the aquarium, and a light source (lamp or lantern) is directed to that place in the dark. As a result, during the night the hydras move to a glass trap, which is then pulled out of the water and doused with boiling water. This remedy can rather be called control over the number of hydras, since this method does not give complete disposal of hydras.

Poorly tolerated hydra and elevated temperature. The method of heating the water in the aquarium is useful if it is possible to catch all the inhabitants of the aquarium valuable to you and transplant them into another container. The water temperature in the aquarium is brought to 42 ° C and kept for 20-30 minutes, turning off the external filter or removing the filler from the internal filter. Then the water is allowed to cool or diluted with hot settled cold water. After that, the living creatures are returned home. Most plants tolerate this procedure well.

Remove hydra and safe if dosages are observed 3% hydrogen peroxide. However, to achieve the desired effect, a solution of hydrogen peroxide at the rate of 40 ml per 100 liters of water must be infused daily for a week. Shrimps and fish tolerate this procedure well, but plants do not.

Of the radical measures - the use of chemistry. For the destruction of hydra, drugs are used, the active substance of which is fenbendazole: Panakur, Febtal, Flubenol, Flubentazole, Ptero Aquasan Planacid and many others. Such drugs are used in veterinary medicine for the treatment of helminthic invasions in animals, and therefore they should be looked for in pet stores and veterinary pharmacies. However, you should pay attention to the fact that the composition of the drug does not include copper or other active substance in addition to fenbendazole, otherwise the shrimp will not survive such treatment. The preparations are available in powder or in tablets, which must be crushed into powder and try to dissolve as much as possible, you can use a brush, in a separate container with water collected from the aquarium. Fenbendazole dissolves poorly, so the resulting suspension, when poured into the aquarium, will give cloudy water and sediment on the ground and on objects in the aquarium. Undissolved particles of the medicine can eat up shrimp, but this is not scary. After 3 days, it is necessary to change the water by 30-50%. According to aquarists, this method is quite effective against hydras, but snails do not tolerate it well, and in addition, biobalance in the aquarium may be disturbed after therapy.

When applying any of the above methods, it is necessary to pay attention to Special attention organic purity in the aquarium: do not overfeed the inhabitants, exclude feeding invertebrates with daphnia or brine shrimp, do water changes on time.

Added on 01/05/19: Dear fellow hobbyists, the author of this article did not test the effect of the preparations indicated in the article on shrimp that are sensitive to changes in water parameters (Sulawesi shrimp, Taiwan bee, Tigerbee). Based on this, the proportions indicated in the article, as well as the use of drugs itself, can be detrimental to your shrimp. As soon as the necessary and verified information on the use of the preparations given in the article in aquariums with shrimp Sulawesi, Taiwan bee, Tigerbee is collected, we will definitely make adjustments to the material presented.

P.s. Too bad there isn't at the moment. veterinary clinics, which aquarists could contact. Indeed, today every family has pets, and their owners, at least once, could use the services of a veterinary clinic. Imagine a competent veterinarian treating your aquarium pet - it's a pity that these are only dreams!

Hydra is the simplest organism from the order Coelenterates. This freshwater polyp lives in almost every reservoir. It is a translucent gelatinous body, similar to a self-moving stomach, where the hydra digests food.

How hydra eats

The size of this simplest organism rarely exceeds 2 cm. Outwardly, the hydra resembles a mucous tube of a greenish or brown color. Its color depends on the food eaten. With one end of the body, it is attached to plants, stones or snags in the water, and with the other it catches prey. Basically, it is small invertebrates - daphnia, cyclops, oligochaetes-naidids. Sometimes small crustaceans, as well as fish fry, serve as food.

The mouth opening of the hydra is surrounded by tentacles, of which there are six to twenty pieces. They are in constant motion. As soon as the victim touches them, located in the tentacles, they immediately throw out a pointed thread containing poison. Plunging into an approaching animal, she paralyzes it and, pulling it up with tentacles, brings it to her mouth. At the same time, it seems that her body, as it were, is put on the victim, who thus finds herself in the intestines, where the digestion of food begins in the hydra. The poison stinging capsule can only be used once, after which it is replaced with a new one.

The structure of the digestive system

The body of the hydra is very similar to a two-layer bag, which is called the ectoderm, and the inner one is the endoderm. Between them is a structureless substance called mesoglea.

The composition of the inner layer, where the hydra digests food, is mainly glandular and digestive cells. The first secrete digestive juice into the intestinal cavity, under the influence of which the food eaten is liquefied and breaks up into small particles. Other cells in the inner layer grab these pieces and pull them in.

Thus, the process of digestion begins in the intestinal cavity, and ends inside the cells of the endoderm. All the remnants of food that could not be digested are thrown out through the mouth.

How does the hydra

The digestive cells of the inner layer have from 1 to 3 flagella at the end, with the help of which small food particles are drawn in and digested. Absence transport system in the body of hydra complicates the task of providing ectoderm cells with nutrients, given that the mesoglea is quite dense. This problem is solved due to the existing outgrowths on the cells of both layers. They cross by connecting through gap junctions. Organic molecules in the form of amino acids and monosaccharides, passing through them, provide nutrition to the ectoderm.

When the waste products of cellular metabolism remain where the hydra digests food, it contracts, resulting in emptying.

Hydra is a genus of animals belonging to the Coelenterates. Their structure and activity are often considered on the example of a typical representative - freshwater hydra. Next, it will be described this species which lives in fresh water clean water attached to aquatic plants.

Usually the size of the hydra is less than 1 cm. The life form is a polyp, which suggests a cylindrical body shape with a sole at the bottom and a mouth opening on the upper side. The mouth is surrounded by tentacles (approximately 6-10), which can be extended in length exceeding the length of the body. The hydra leans in the water from side to side and with its tentacles catches small arthropods (daphnia, etc.), after which it sends them into the mouth.

For hydras, as well as for all coelenterates, it is characteristic radial (or radial) symmetry. If you look at not from above, then you can draw a lot of imaginary planes dividing the animal into two equal parts. Hydra does not care which side food swims up to it, since it leads a motionless lifestyle, therefore, radial symmetry is more beneficial for it than bilateral symmetry (characteristic of most mobile animals).

Hydra's mouth opens into intestinal cavity. This is where the digestion of food takes place. The rest of digestion is carried out in cells that absorb partially digested food from the intestinal cavity. Undigested residues are ejected through the mouth, since coelenterates do not have an anus.

The body of the hydra, like all coelenterates, consists of two layers of cells. The outer layer is called ectoderm, and the inner endoderm. Between them there is a small layer mesoglea- non-cellular gelatinous substance, which may contain Various types cells or cell extensions.

Hydra ectoderm

Hydra ectoderm is made up of several types of cells.

skin muscle cells the most numerous. They create the integuments of the animal, and are also responsible for changing the shape of the body (elongation or reduction, bending). Their processes contain muscle fibers that can contract (while their length decreases) and relax (their length increases). Thus, these cells play the role of not only covers, but also muscles. Hydra does not have real muscle cells and, accordingly, real muscle tissue.

The Hydra can move around using somersaults. She leans so hard that she reaches the support with her tentacles and stands on them, lifting the sole up. After that, the sole already leans and becomes on a support. Thus, the hydra makes a somersault and finds itself in a new place.

The hydra has nerve cells . These cells have a body and long processes that connect them to each other. Other processes are in contact with skin-muscle and some other cells. Thus, the whole body is enclosed in a nervous network. Hydra does not have an accumulation of nerve cells (ganglia, brain), however, even such a primitive nervous system allows them to have unconditioned reflexes. Hydras respond to touch, the presence of a number chemical substances, temperature change. So if you touch the hydra, it shrinks. This means that excitation from one nerve cell spreads to all the others, after which the nerve cells transmit a signal to the skin-muscle cells so that they begin to contract their muscle fibers.

Between the skin-muscle cells, the hydra has a lot of stinging cells. Especially a lot of them on the tentacles. These cells inside contain stinging capsules with stinging filaments. Outside, the cells have a sensitive hair, when touched, the stinging thread shoots out of its capsule and strikes the victim. In this case, poison is injected into a small animal, usually having a paralytic effect. With the help of stinging cells, the hydra not only catches its prey, but also defends itself from animals attacking it.

intermediate cells(located in the mesoglea rather than in the ectoderm) provide regeneration. If the hydra is damaged, then thanks to the intermediate cells, new ones form at the site of the wound. various cells ectoderm and endoderm. The Hydra can regenerate a fairly large portion of its body. Hence its name: in honor of the character of ancient Greek mythology, who grew new heads to replace the severed ones.

Hydra endoderm

The endoderm lines the intestinal cavity of the hydra. The main function of endoderm cells is to capture food particles (partially digested in the intestinal cavity) and their final digestion. At the same time, endoderm cells also have muscle fibers that can contract. These fibrils are directed towards the mesoglea. Flagella are directed towards the intestinal cavity, which scoop up food particles to the cell. The cell captures them the way amoeba do - forming pseudopods. Further, the food is in the digestive vacuoles.

The endoderm secretes a secret into the intestinal cavity - digestive juice. Thanks to him, the animal captured by the hydra breaks up into small particles.

Hydra breeding

The freshwater hydra has both sexual and asexual reproduction.

asexual reproduction carried out by budding. It takes place in favorable period year (mostly in summer). A protrusion of the wall forms on the body of the hydra. This protrusion increases in size, after which tentacles form on it and a mouth erupts. Subsequently, the daughter individual is separated. Thus, freshwater hydras do not form colonies.

With the onset of cold weather (in autumn), the hydra transgresses to sexual reproduction. After sexual reproduction, hydras die, they cannot live in winter. During sexual reproduction in the body of the hydra, eggs and sperm are formed. The latter leave the body of one hydra, swim up to another and fertilize her eggs there. Zygotes are formed, which are covered with a dense shell that allows them to survive the winter. In the spring, the zygote begins to divide, and two germ layers are formed - the ectoderm and endoderm. When the temperature gets high enough, the young hydra breaks the shell and comes out.

The body shape of hydra is tubular. The mouth opening of these animals is covered with tentacles. Hydras live in water, and with their stinging tentacles they kill and bring prey to their mouths.

   Type - Coelenterates
   Class - hydroid
   Genus/Species - Gidra vulgaris, H. oligactis and others.

   Basic data:
DIMENSIONS
Length: 6-15 mm.

BREEDING
Vegetative: has a budding character. A kidney appears on the body of the mother individual, from which the daughter individual gradually develops.
Sexual: most types of hydras have separate sexes. The gonads accumulate cells from which eggs develop. Sperm develop in the testis.

LIFESTYLE
Habits: live in fresh brackish waters.
Food: plankton, fish fry, ciliates.
Lifespan: no data.

RELATED SPECIES
More than 9,000 species belong to the type of coelenterates, some of them (15-20) live only in fresh waters.

   Freshwater hydras are one of the most small predators. Despite this, they are able to provide themselves with food. Hydras have a tubular body shape. With the help of the sole, they attach themselves to underwater plants or rocks and move their tentacles in search of prey. Green hydras contain photosynthetic algae.

FOOD

   Hydra is a predatory animal that lives in water. It feeds on small organisms that live in the water, such as ciliates, small bristle worms, planktonic crustaceans, water fleas, insects and their larvae, as well as fish fry. A hunting hydra attaches itself to an aquatic plant, branch or leaf and hangs on them. Her tentacles are very wide open. They constantly make circular search movements. If one of them touches the victim, others rush to him. Hydra paralyzes prey with stinger cell venom. Hydra pulls paralyzed prey with tentacles to the mouth opening. She swallows small animals whole. If the prey is larger than the hydra, the predator opens its mouth wide, the walls of its body stretch. If such prey is so large that it does not fit into the gastric cavity, then the hydra swallows only part of it and, to the extent of digestion, pushes the victim deeper and deeper.

LIFESTYLE

   Hydras live alone. However, in places that are especially rich in food, several hydras hunt at once. This happens because water current brings a lot of food to certain place. Hydras of the genus Nuiga prefer fresh water. These animals were discovered by the researcher who invented the microscope, A. Leeuwenhoek (1632-1723). Another scientist, G. Tremblay, discovered that hydras easily restore lost body parts. A nondescript tubular body topped with tentacles that grow around the mouth opening and a sole at the end of the body are the main features appearance hydras. The gastric cavity of this animal is continuous. The tentacles are hollow. The walls of the body are composed of two layers of cells. There are glandular cells located in the middle part of the hydra body. Different kinds very similar to each other. They differ mainly in color (and, as a result, different colors talk about some structural feature). Hydras are bright green in color, symbiotic algae live in the body. Hydras react to light and swim towards it. These animals are immobile. They spend most of their lives attached, waiting for prey. With a sole, like a sucker, hydras are firmly attached to plants.

BREEDING

    Hydras reproduce in two ways - sexually and vegetatively. Vegetative propagation is represented by budding. With suitable external conditions several buds develop on the body of the hydra. At the very beginning, the bud looks like a small mound, later miniature tentacles appear on its outer end. The tentacles grow, stinging cells appear on them. Bottom part the body of the daughter individual becomes thinner, the mouth opening opens at the hydra, the young individual branches off and begins an independent life. These animals reproduce by budding in warm time of the year. With the onset of autumn, hydras begin sexual reproduction. Sex cells are formed in the gonads. The gonad cracks and an egg comes out of it. At about the same time, spermatozoa are formed in the testes of other hydras. They also leave the gonad and swim in the water. One of them fertilizes the egg. The embryo develops in the egg. Under the protection of a double shell, it hibernates at the bottom. In the spring, a fully formed hydra emerges from the egg.
  

DO YOU KNOW WHAT...

  • The Hydra does not age, as every cell in its body is renewed after a few weeks. This animal lives only in the warm season. With the onset of winter, all adult hydras die. Only their eggs, protected by a strong double shell, the embryotheca, can overwinter.
  • Hydras easily regenerate their lost limbs. The scientist G. Tremblay (1710-1784), as a result of his numerous experiments, received a seven-headed polyp, in which severed heads grew. He looked like mythical creature- Lernaean Hydra defeated by a hero ancient greece- Hercules.
  • During constant movements in the water, the hydra produces quite original acrobatic stunts.
  

CHARACTERISTIC FEATURES OF THE HYDRA

   Tentacles: the mouth opening is surrounded by a corolla with 5-12 tentacles with stellate cells. With their help, the animal paralyzes the prey and pulls it into the mouth. The hydra, which hunts, attaches itself to a hard surface, and, spreading its tentacles wide, makes circular search movements with them.
   Body: tubular body shape. At the front end is a mouth opening surrounded by tentacles. The aboral pore is located in the middle of the sole. The wall of the hydra consists of two layers of cells. Digestive processes take place in the middle part of the body.
   mouth opening: covered with a corolla of tentacles. With tentacles, the hydra pulls the animal into its mouth and swallows it.
   Leg: the back end of the hydra is narrowed - this is a leg that has a sole at the end.
   Gonads: are formed in the ectoderm and look like tubercles. They accumulate sex cells.
   Dome: length about 13 mm. This is for self defense. The hydra is charged and forms a dense dome.
   Bud: vegetative propagation hydra has the character of budding. Several kidneys can appear on the body at the same time. The kidneys are growing fast.

PLACES OF ACCOMMODATION
Freshwater hydras live in fresh and brackish waters. They inhabit rivers, lakes, swamps and other bodies of water. The most widespread species are ordinary and brown hydra.
PRESERVATION
Each species of the genus living on certain territory. Today, they are not in danger of extinction.

Movement. Hydra can move from place to place. This movement occurs in different ways: either the hydra, bending in an arc, is sucked by the tentacles and partly by the glandular cells surrounding the mouth to the substrate and then pulls the sole, or the hydra, as it were, “tumbles”, attaching alternately with the sole, then with the tentacles.

Nutrition. Stinging capsules with their threads entangle prey and paralyze it. The prey processed in this way is captured by tentacles and sent to the mouth opening. Hydras can "overpower" very big booty, exceeding them in magnitude, for example, evenfish fry. The extensibility of the mouth opening and the whole body is great. They are very voracious - one hydra can swallow for short term up to half a dozen daphnia. Swallowed food enters the gastric cavity. Digestion in hydras, apparently, is combined - intra- and extracellular. Food particles are pulled in by endoderm cells with the help of pseudodopodia inside and digested there. As a result of digestion, endoderm cells accumulate nutrients, grains of excretion products appear there, thrown out from time to time in small portions into the gastric cavity. Excretion products, as well as undigested parts of food, are thrown out through the mouth


I - individual with male gonads; II - individual with female gonads

reproduction. Hydra reproduce asexually and sexually. Etc; asexual reproduction on hydras, kidneys are formed, gradually breaking away from the mother's body. Budding of hydras under favorable nutritional conditions can be very intense; observations show that in 12 days the number of hydras can increase 8 times. During summer period hydras usually reproduce by budding, but with the onset of autumn, sexual reproduction, and hydras can be both hermaphroditic and dioecious (stalked hydra).

Sex products are formed in the ectoderm from interstitial cells. In these places, the ectoderm swells in the form of tubercles, in which either numerous spermatozoa or one amoeboid egg are formed. After fertilization, which occurs on the body of the hydra, the egg cell is covered with a shell. Such a shelled egg overwinter, and in the spring a young hydra emerges from it. The larval stage of hydra is absent.

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