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Appearance, movement and nutrition of freshwater hydra

One of the typical representatives of the order of intestinal animals – freshwater hydra. These creatures dwell in clear waters and attach themselves to plants or the ground.

The Dutch inventor of the microscope and the famous naturalist A. Leeuwenhoek saw them for the first time. The scientist even managed to witness the hydra budding and examine its cells.

Later, Karl Linney gave the genus a scientific name, referring to the ancient Greek myths about the Lernean hydra.

This aquatic inhabitant has a miniature size. On average, body length is from 1 mm to 2 cm, but it can be a little more.

The creature has a cylindrical body. The mouth is located in front with tentacles around (their number can be up to twelve).

Behind is the sole, through which the animal moves and attaches to something.

On the sole is a narrow pore, through which the fluid and gas bubbles from the intestinal cavity pass. Together with the bubble, the creature detaches from the chosen support and emerges.

At the same time his head is located in the midst of water. Hydra has a simple structure, its body consists of two layers.

Oddly enough, but when a creature is hungry, its body looks longer.

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Hydras are one of the few intestinal cavities that live in fresh water. Most of these creatures inhabit the marine area.. Freshwater species may have the following habitat:

If the water is clear and clean, these creatures prefer to be near the shore, creating a kind of carpet. Another reason why animals prefer shallow areas is the love of light. Freshwater creatures very well distinguish the direction of light and move closer to its source.

If you put them in an aquarium, they will surely swim to the most illuminated part.

Interestingly, unicellular algae (zoochlorella) may be present in the endoderm of this creature. This is reflected in the appearance of the animal – it takes on a light green color.

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This miniature creature is a real predator. It is very interesting to know what a freshwater hydra eats.

Many small animals live in the water: cyclops, ciliates, and also crustaceans. They serve as food for this creation. Sometimes it can eat larger prey, for example, small worms or mosquito larvae.

In addition, these intestinal cavities bring great damage to fish ponds, because the caviar becomes one of the things that hydra eats.

In the aquarium, you can observe how this animal hunts in all its glory. Hydra hangs tentacles down and at the same time puts them in the form of a network. Her torso sways slightly and describes a circle.

The prey sailing nearby touches the tentacles, tries to escape, but abruptly ceases to move. Strange cells paralyze her.

Then the intestinal cavity attracts it to the mouth and eats it.

If the animal has eaten well, it swells. This creature can devour the victim., which exceeds it in size. His mouth can open very widely, sometimes part of the body of the prey is clearly visible from it.

After such a spectacle, there is no doubt that the freshwater hydra is a predator in the way of feeding.

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If the creature is sufficiently nourished, reproduction occurs very quickly by the budding method. In a few days, a tiny kidney grows to a formed individual. Often, several such buds appear on the body of the hydra, which are then separated from the maternal organism.

This process is called asexual reproduction.

In the autumn, when the water gets colder, freshwater creatures can also reproduce by sex. This process is as follows:

  1. Sexual glands appear on the body of the individual. In some of them, male cells are formed, and in others – the egg cells.
  2. Male germ cells move in the water and enter the body cavity of the hydra, fertilizing the eggs.
  3. When eggs are formed, hydra most often dies, and new individuals are born from eggs.

In one of the layers of the body of this creature is the disseminated nervous system, and in the other – a small number of nerve cells. In total, the animal body has 5 thousand neurons.

Near the mouth, on the sole and tentacles, the animal has nerve plexuses.

The hydra does not divide neurons into groups. The cells perceive irritation and give a signal to the muscles. In the nervous system of the individual there are electrical and chemical synapses, as well as opsin proteins.

Speaking about what the hydra breathes, it is worth mentioning that the process of excretion and respiration occurs on the surface of the whole body.

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Freshwater polyp cells are in the process of constant renewal. In the middle of the body they divide, and then move to the tentacles and the sole, where they die.

If there are too many dividing cells, they move to the lower region of the body.

This animal has an amazing ability to regenerate. If you cut his torso across, each part will be restored to its previous form.

In the XIX century there was a lot of talk about the immortality of the animal. Some researchers tried to prove this hypothesis, while others wanted to refute it.

In 1917, after a four-year experiment, the theory was proved by D. Martinez, as a result, the hydra officially began to belong to the everlasting creatures.

Immortality is associated with an incredible ability to regenerate. The death of animals in winter is associated with adverse factors and lack of food.

Freshwater hydras are entertaining creatures. Four species of these animals are found throughout Russia. and they are all similar.

The most common are common and stalked hydra. Going to swim in the river, you can find on its shore a carpet of these green creatures.

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