Protozoa are parasites. The meaning of the word parasitism in the encyclopedia of biology Definition of parasitism in biology

The real ones, which are actually in another organism, are excreted in its feces, where they can be found (house fly larvae);

False (imaginary), which can accidentally end up in feces brought, for example, for analysis (flies can lay eggs on them, and larvae quickly hatch from them).

1. Depending on the number of probable hosts:

Euryxenni (from Greek.ωύρύω - wide) - those that have a wide range of hosts (ixodid ticks, mosquitoes);

Heteroxenni (from Greek.έτερος - different, different) - those that undergo complex development cycles at the expense of several hosts. Yes, dog tick passes three stages of development: larva, nymph, imago - and at each stage it has its own host.

Temporary - those that live outside the host’s body and attack it only to feed on blood (ticks, fleas, mosquitoes, mosquitoes) lasting from half a minute to several days;

Permanent - live in the host’s body or on its integument at all stages of development.

3. Depending on the location:

External - live on the outer integument of the host (lice, fleas, mosquitoes);

Cutaneous - live in the thickness of the skin, and partly on its surface (scabies);

Cavity - live in a cavity that communicates with the external environment - in the external auditory canal, in the nasal cavity (Wohlfart fly larvae).

Cavity - live in the body cavities of internal organs (ascaris, gostrik);

Tissue - in muscle, nervous tissues (Trichinela);

Internal octopuses (sporophores, flagellates).

Living things in nature react to each other and enter into relationships in different ways. One such type of communication between two organisms is commensalism or freeloading. Examples of such relationships are found quite often in nature. Let's look at the brightest of them.

Definition of freeloading (commensalism)

The relationships formed between organisms that interact in nature can be symbiotic in nature. One type of symbiosis is called freeloading, where one organism benefits from the relationship while the other species receives neither benefit nor harm. There are four areas of benefit in total:

1. Nutrition.
2. Housing.
3. Transportation.
4. Seed dispersal.

Types of commensalism

Most environmental experts group commensal relationships into the following types:

• Chemical commensalism is most often observed between two species of bacteria, one of which feeds on the chemicals or waste of the other.
• Inquilinism - one animal uses the body or body cavity of another organism as a shelter or living space.
• Entoikia is a form of commensalism that occurs when one species inadvertently creates a home inside the cavity of another but has access to the outside environment.
• Phoresia occurs when one organism attaches itself to another organism for the purpose of transport.
• Sinoikia (tenancy) occurs when one living being uses another being or its dwelling as its home.

Examples of freeloading

Commensalism is a scientific term that characterizes the relationship between two living beings from different species, in which one of the organisms benefits for itself, while the other, as they say, is neither hot nor cold. Often commensalism occurs between a large animal and a smaller one. Here are some examples of freeloading:

• Some shells cannot move independently and are attached to certain inhabitants of the sea, such as whales. The former benefit from being able to transport throughout the ocean. The latter receive neither benefit nor harm from this connection.
• The egret follows herds of cattle and feeds on the insects that follow them.
• The monarch butterfly extracts a toxic chemical from the milkweed plant and stores it in its body for protection from predators.
• Remora fish and shark are good examples of commensalism.

The term "commensalism"

Commensalism is the scientific term for the concept of freeloading. In terms of time, this type of relationship can be quite short, or it can take the form of a lifelong symbiosis. The term was coined in 1876 by Belgian paleontologist and zoologist Pierre-Joseph van Beneden, who originally used the word to describe the activity of companion animals that followed predators to finish their prey. The word "commensalism" comes from the Latin word commensalis, which means "sharing, at one table" (com - together, mensa - meal).

Examples of parasites are very common. Wood frogs use plants as protection. Jackals excluded from the pack will follow the tiger to steal the remains of its meal. The small fish live on other marine animals, changing color to blend in with their host, thereby gaining protection from predators.

Burdock produces spiny seeds that cling to animal fur or people's clothing. Plants rely on this method of seed dispersal to reproduce, while animals are unaffected.

Freeloading: examples of animals and plants

Commensalistic relationships are also those in which one organism forms a habitat for another. An example of freeloading in this case is the hermit crab - here a shell from a dead gastropod is used for protection. Another example would be larvae living on a dead organism.

The animal is attached to another for transport. This type of commensalism is most often found in arthropods such as insect-dwelling mites. Other examples include anemone attachment to hermit crab shells, mammal-riding pseudoscorpions, and bird-riding centipedes.

Commensal organisms can form communities within the host organism. An example of such freeloading is the bacterial flora found on human skin. Scientists debate whether microbiota is truly a type of commensalism. For example, in the case of skin flora, there is evidence that bacteria confer some protection on the host (which would be reciprocated).

Pets and commensalism

Dogs, cats, and other animals also appear to have commensal relationships with humans. It is believed that the ancestors of dogs followed hunters to eat the remains of carcasses. Over time, the "cooperation" became mutual, with humans also taking advantage of the relationship to gain protection from other predators and assistance in tracking prey.

Marine "freeloaders"

Examples of freeloading in nature are relationships between individuals of two species in which one species receives food or other benefits from the other without harming or benefiting the latter. A pilot fish swims next to a white shark. Thanks to the flat oval sucking disc structure at the top of its head, the remora fish adheres to its host's body. Both of these parasite fish feed on the leftover food of their owners. One of the best known examples of commensalism in the ocean is the relationship that exists between clones and sea anemones.

Examples of freeloading in biology are clearly shown between organisms, which is beneficial for one of them, and neutral for the other. Many cases of commensalism are surrounded by controversy, since there is always the possibility that the commensal host also benefits or is harmed in ways as yet unknown to science.

Relationships of this type are of great importance in nature, as they promote closer cooperation among species, more efficient exploration of space, and an enriched diversity of food resources.

Forming cysts, amoebas leave the human body with undigested food debris. Light cysts spread easily. If you don't wash your hands and food, you can become infected.

Malarial plasmodium

If a person with malaria is bitten again by a malaria mosquito, the plasmodia will now be transferred from the person to the mosquito. Plasmodium reproduces sexually in the body of a mosquito.

Malaria is common in Africa. This is a very dangerous disease. Malaria is fought, among other things, by destroying malaria-carrying mosquitoes.

Trypanosomes

The vector of sleeping sickness is the tsetse fly. This disease is typical for tropical Africa. Sleeping sickness develops in two stages: in the first weeks a person is tormented by fever and pain, after a month or more drowsiness sets in, disturbances in sleep and coordination, and changes in consciousness. The disease is easier to treat in the first stage.

Giardia

A person becomes infected with giardiasis by eating unwashed food containing Giardia cysts. Having emerged from the cyst, lamblia attaches itself to the intestines and feeds on digested food.

Leishmania

There are different types of leishmaniasis associated with damage to various tissues of the body. One of them is the skin disease Pendensky ulcer.

Coccidia

Coccidia include the genus Toxoplasma. Their representatives cause such a widespread disease in humans as toxoplasmosis. A person becomes infected from pets or poorly prepared meat food. Toxoplasma affects many organs, including the nervous system.

Food, in whatever form, is essential for the survival of living things. Millions of years have resulted in a variety of foraging strategies, and these different interactions are the glue that binds everything together.

Some feeding strategies are more familiar to us, such as carnivores (and plants), which eat other animals, and herbivores, which eat plants. However, there are different types of symbiotic relationships that involve closer and more complex interactions.

It is a partnership between organisms in which each of the life forms involved benefits the other.

This is when one organism uses another for its own purposes, but without causing obvious harm to it. An example is mosses growing on the bark of a tree.

Gaul

Some galls, such as inknuts on oak leaves (caused by wasps), support insect communities, which in turn can provide food for birds. Look at the crown of a birch tree and you will see dense branch structures that look a lot like birds' nests. This is the result of infection with fungi of the species - Taphrina betulina.

Externally and internally, these organisms have exactly the same structure as all other single-celled organisms. They have only one structural unit, but it is capable of performing all the vital functions necessary for normal life. Namely:

• grows and develops;
• reproduces;
• eats;
• breathes;
• has excitability and irritability;
• moves.

They reproduce quite quickly, asexually. The mother cell simply, upon reaching maturity, splits into several daughter cells. They lead independently immediately after education.

The various representatives of the organisms under consideration can be classified as follows.

Leishmania

Settling inside the host cells, which for Leishmania are insects and mammals, including humans, they cause gradual death of the structure. In a person, an open gaping ulcer forms on the skin, in the place where Leishmania lives, which constantly rots. This disease is called rubber or Baghdad ulcer. Treatment is very difficult and lengthy, with surgical intervention.

Single-celled organisms of this group are transmitted by mosquitoes, which is why foci of leishmaniasis are found in tropical and subtropical countries.

Cysts are located in the large intestine and are therefore excreted with solid waste products. They become infected through dirt and water. Therefore, personal hygiene rules are especially important in the prevention of giardiasis.

This class includes different types of amoeba:

• intestinal;
• dysenteric;
• oral

Unlike the form considered, intestinal amoeba is present in the body of almost every person and lives in harmony with it. It does not release toxic substances and does not penetrate the intestinal walls. Therefore, it does not cause any particular discomfort or harm to health.

Inhabitant of dental plaque and caries formations. Feeds on bacteria and can consume red blood cells. Its exact meaning for humans is not yet clear.

Balantidium coli

This organism is a representative of the class Ciliates. A fairly large oval single-celled organism that settles in. It is here that it takes hold and drills into the wall of the organ, causing the appearance of bleeding, festering wounds. Cysts of this protozoan easily enter the bloodstream. This is how dispersal occurs throughout the body.

Infection with protozoan cysts occurs through contact of mucous membranes with dirty hands or when drinking raw water. The disease caused by these creatures is called balantidiasis. Accompanied by vomiting with blood, diarrhea, weakness, severe colic in the abdominal cavity.

The disease that is caused directly by Trichomonas is called trichomoniasis. It is sexually transmitted and threatens infertility in both men and women.

Signs of the disease in children

• general weakness;
• fatigue;
• pallor;
• headaches;
• decreased appetite;
• poor sleep;
• irritability;
• loose stools;
• vomiting and others.