Mutually beneficial cohabitation of living organisms is called. Mutually beneficial relationships in the animal world. The term "biocenosis" was introduced

Detailed solution paragraph § 77 in biology for 10th grade students, authors Kamensky A.A., Kriksunov E.A., Pasechnik V.V. 2014

• Gdz workbook in Biology for grade 10 you can find

1. What biotic environmental factors do you know?

2. What types of competition do you know?

Answer. Competition - in biology, any antagonistic relationship associated with the struggle for existence, for dominance, for food, space and other resources between organisms, species or populations of species that need the same resources.

Intraspecific competition is competition between representatives of one or more populations of a species. Goes for resources, intra-group dominance, females/males, etc.

Interspecific competition is competition between populations different types non-adjacent trophic levels in a biocenosis. It is due to the fact that representatives of different species jointly use the same resources, which are usually limited. Resources can be either food (for example, the same types of prey for predators or plants for phytophages), or of another kind, for example, the availability of places for breeding offspring, shelters for protection from enemies, etc. Species can also compete for dominance in the ecosystem. There are two forms of competitive relationships: direct competition (interference) and indirect competition (exploitation). With direct competition between populations of species in a biocenosis, antagonistic relationships (antibiosis) evolve evolutionarily, expressed by various types of mutual oppression (fights, blocking access to a resource, allelopathy, etc.). In indirect competition, one of the species monopolizes a resource or habitat, thereby worsening the conditions for the existence of a competitive species of a similar ecological niche.

Both evolutionarily (taxonomically) close species and representatives of very distant groups can compete in nature. For example, gophers in the dry steppe eat up to 40% of plant growth. This means that pastures can support fewer saigas or sheep. And in the years mass reproduction The locusts do not have enough food for either the gophers or the sheep.

3. What is symbiosis?

Typically, symbiosis is mutualistic, i.e. the cohabitation of both organisms (symbionts) is mutually beneficial and arises in the process of evolution as one of the forms of adaptation to the conditions of existence. Symbiosis can occur both at the level of multicellular organisms and at the level of individual cells (intracellular symbiosis). Plants can enter into symbiotic relationships with plants, plants with animals, animals with animals, plants and animals with microorganisms, microorganisms with microorganisms. The term “symbiosis” was first introduced by the German botanist A. de Bary (1879) as applied to lichens. A striking example of symbiosis among plants is mycorrhiza - the cohabitation of the mycelium of a fungus with the roots of a higher plant (hyphae entwine the roots and contribute to the supply of water and minerals from the soil); Some orchids cannot grow without mycorrhizae.

Nature knows numerous examples of symbiotic relationships from which both partners benefit. For example, the symbiosis between leguminous plants and soil bacteria Rhizobium is extremely important for the nitrogen cycle in nature. These bacteria - also called nitrogen-fixing bacteria - settle on the roots of plants and have the ability to “fix” nitrogen, that is, to break down the strong bonds between the atoms of atmospheric free nitrogen, making it possible to incorporate nitrogen into compounds accessible to the plant, such as ammonia. In this case, the mutual benefit is obvious: the roots are a habitat for bacteria, and the bacteria supply the plant with the necessary nutrients.

There are also numerous examples of symbiosis that is beneficial for one species and does not bring any benefit or harm to another species. For example, the human intestine is inhabited by many types of bacteria, the presence of which is harmless to humans. Similarly, plants called bromeliads (which include, for example, pineapple) live on tree branches, but receive nutrients from the air. These plants use the tree for support without depriving it of nutrients.

A type of symbiosis is endosymbiosis, when one of the partners lives inside the cell of the other.

The science of symbiosis is symbiology.

Questions after § 77

1. What examples do you know of positive and negative interactions between organisms of different species?

2. What is the essence of the predator-prey relationship?

Answer. Predation (+ −) is a type of relationship between populations in which representatives of one species eat (destroy) representatives of another, i.e., organisms of one population serve as food for organisms of another. The predator usually catches and kills its prey itself, after which it eats it completely or partially. Such predators are characterized by hunting behavior. But besides predator-hunters, there is also large group predator-gatherers whose feeding method consists of simply searching and collecting prey. These are, for example, many insectivorous birds that collect food on the ground, in the grass or in trees.

Predation is a widespread form of communication, not only between animals, but also between plants and animals. Thus, herbivory (eating plants by animals) is, in essence, also predation; on the other hand, a number carnivorous plants(sundew, nepenthes) can also be classified as predators.

However, in a narrow, ecological sense, only the consumption of animals by animals is considered predation.

4. Which ones are the most famous examples Are you familiar with symbiotic relationships?

Answer. Symbiotic relationships in which stable, mutually beneficial cohabitation of two organisms of different species are observed is called mutualism. Such are, for example, the relationships between the hermit crab and the sea anemone, or highly specialized plants for pollination with the insect species that pollinate them (clover and bumblebee). Nutcracker feeding only on seeds (nuts) cedar pine, is the only distributor of its seeds. Mutualism is very widely developed in nature.

5. How do you understand mutualism and symbiosis?

Nature is beautiful and diverse. Existing on the same planet, plants and animals were forced to learn to coexist with each other. The relationship between organisms is complex, but interesting topic, which will help you better understand the world around you.

Types of relationships

Eat different kinds relationships with each other. But scientists divide them into three large groups.

The first group combines all those types of relationships between organisms that can be called positive, the result of which helps two organisms to exist without contradictions.

The second group includes those types of relationships that are called negative. As a result of the interaction of two organisms, only one benefits, while the other is oppressed. Sometimes the latter may even die as a result of such relationships. This group also includes such interaction of organisms that negatively affects both the first and second individuals.

The third group is considered the smallest. This group includes relationships between organisms that bring neither benefit nor harm to both parties.

Positive types of relationships between organisms

In order to exist in the world, you need to find allies and helpers. This is exactly what many plants and animals do throughout their lives. evolutionary development. The result is connections where both parties benefit from the relationship. Or those relationships that are beneficial only to one side, and they do not harm the other.

Positive relationships, also called symbiosis, come in many forms. Currently, cooperation, mutualism and commensalism are distinguished.

Cooperation

Cooperation is a relationship between living organisms where both parties benefit. Most often this benefit comes from obtaining food. But sometimes one of the parties receives from the other not only food, but also protection. Such relationships between organisms are very interesting. Examples can be seen in the animal kingdom in different parts planets.

One of them is the cooperation of hermit crab and sea anemone. Thanks to the sea anemone, the crayfish finds a home and protection from other inhabitants of the aquatic space. Without the hermit crab, the sea anemone cannot move. But cancer allows you to expand the radius of searching for food. In addition, what the sea anemone does not eat will sink to the bottom and go to the crayfish. This means that both parties benefit from this relationship.

Another example was the relationship between rhinoceroses and cowbirds. Such relationships between organisms allow one of the parties to find food. Cowbirds eat insects, which live in abundance on the huge rhinoceros. Rhinos also benefit from neighbors. Thanks to these birds he can lead healthy life and don't worry about insects.

Commensalism

Commensalism is those relationships between organisms in ecosystems when one of the organisms benefits, and the second does not experience inconvenience from these relationships, but does not benefit either. This type of relationship is also called freeloading.

Sharks are creepy sea ​​predators. But for sticky fish, they become a chance to survive and protect themselves from other aquatic predators, which are weak compared to sharks. Sticky fish benefit from sharks. But they themselves do not bring them any benefit. At the same time, there is no harm. For the shark, such relationships go unnoticed.

In rodent burrows you can find not only babies, but also a huge number of different insects. The hole created by the animal becomes their home. It is here that they find not only shelter, but also protection from those animals that love to feast on them. In a rodent burrow, the insect is not afraid of this. Moreover, here they can find enough food to lead a life without troubles. Rodents do not experience any difficulties from these types of relationships.

Negative types of relationships between organisms

Existing together on the planet, animals can not only help each other, but also cause harm. It is not easy to learn these relationships between organisms. The table will help schoolchildren and students.

Predation

Anyone can tell you what predation is without preparation. This is the relationship between organisms when one side benefits and the other suffers. In order to better understand who eats whom, you can compile And then it is easy to find out that many herbivores become food for other animals. At the same time, predators can also be someone's food.

Despite the fact that hedgehogs are often depicted in pictures with apples and mushrooms, they are predators. Hedgehogs feed on small rodents. But they also cannot feel safe. They can be eaten by foxes. In addition, foxes, like wolves, feed on hares.

Despite bloodthirsty predators hunting for weaker animals day and night, competition is considered the most cruel type of relationship between organisms. After all, these include the struggle for a place in the sun among representatives of the same species. And each species has its own means of obtaining the required amount of food or better housing.

Stronger and more agile animals win the fight. Strong wolves get good prey, while others are left either to feed on other, less nourishing animals, or to die of hunger. A similar struggle is waged between plants to get as much moisture or sunlight as possible.

Neutral relationship

There are also types of relationships between organisms when both parties receive neither benefit nor harm. Despite the fact that they live in the same territory, they have absolutely nothing in common. If one of the parties to this relationship disappears from the face of the planet, then the other party will not be directly affected.

So, in warm countries different herbivores feed on the leaves of the same tree. Giraffes eat the leaves that are on top. They are the most juicy and delicious. And other herbivores are forced to feed on the remains growing below. Giraffes do not bother them and do not take away their food. After all, low animals will not be able to reach the leaves that tall animals eat. And it makes no sense for tall people to bend over and take food from others.

Eat different shapes relationships between organisms. And learning them all is not so easy. But it is important to remember that everything in nature is interconnected. Most often, animals and plants influence each other positively or negatively, less often they do not influence each other at all. But even if they are not directly related, this does not mean that the disappearance of one cannot lead to the death of the other. The relationship between organisms is an important part of the surrounding world.

Over the entire history of its existence, humans have domesticated about 40 species of animals. Having provided them with food and given them shelter from enemies, he received in return food, clothing, means of transportation, and labor.

However, even before the appearance of man on Earth, animals united among themselves in “friendly” unions. Ants and termites surpassed everyone in this regard: they “domesticated” about 2,000 species of living creatures! For life together Most often, two or three species usually unite, but they provide each other with such important “services” that sometimes they lose the opportunity to exist separately.

TEMPORARY BUT IMPORTANT COOPERATION

Everyone knows that wolves hunt moose in packs, and dolphins hunt for fish in herds. Such mutual assistance is natural for animals of the same species. But sometimes “outsiders” join together to hunt. This happens, for example, in the steppes Central Asia, where the corsac fox and a small ferret-like animal live.

Both of them are interested in a large gerbil, which is quite difficult to catch: the fox is too fat to fit into the rodent's hole, and the bandage, which can do this, cannot catch the animal at the exit of the hole: while it makes its way underground, the gerbil goes through the emergency passages.

But when two hunters cooperate, they are invariably accompanied by luck: the bandage drives the gerbils to the surface, and the fox is on duty outside, at the exit of the hole, preventing the animal from leaving. As a result, the loot goes to whoever gets to it first. Sometimes it's a fox, sometimes it's a bandage. It happens that they run from hole to hole until they are both satiated. And a few days later they wait for each other in their hunting area and begin a new roundup.

ONE-SIDED BENEFIT

Sometimes only one party benefits from cohabitation. Such relationships can be considered “free-for-all.” An example here would be the coot union ( waterfowl the size of a duck) and carp, whose schools follow the birds.

The reason for this “friendship” is obvious: when diving for algae, their main food, coots stir up silt, in which many small organisms that are tasty for fish are hidden. This is what attracts carp, who want to make money without making any effort.

Small animals often feed on leftover food for more than strong beast or birds, turning into their companions. Polar bears, for example, are accompanied in difficult times winter time arctic foxes and white gulls.

Gray partridges do not fly far from hares, who are better at shoveling snow. Hyenas and jackals strive to be closer to the king of beasts, the lion. There is no benefit or harm to the prey animal from such a “union,” but the “freeloaders” are extremely interested in it.

ENEMIES CAN BECOME DEFENDERS

A person visiting the tundra for the first time will probably be surprised to see geese and a peregrine falcon (classic models of “predator” and “prey”!) nesting in the same territory. It's like meeting a hare fearlessly walking near a wolf's den.

The answer to such good neighborliness is that the peregrine falcon never hunts near its nest: its hunting and nesting areas do not coincide. In addition, he hunts only in the air, which geese are well aware of.

They even developed the habit of taking off and landing away from their nests and reaching them by land. Proximity to the falcon gives the geese considerable advantages: by protecting its offspring from uninvited guests, it involuntarily becomes a formidable protector of the goose family. Whether the peregrine falcon receives any benefits from such “cohabitation” is still unknown.

MUTUAL SERVICES

Impressed by his trip to Ceylon, Ivan Bunin wrote the following lines at the beginning of the last century:

Lagoon near Ranna
-like a sapphire.
There are red roses all around
flamingo,
They're dozing in the puddles
buffalos. On them
The herons stand and turn white,
and with a buzz
The flies are sparkling...

They not only feed, but also reproduce on their body in unimaginable quantities. From the fur of some livestock you can sometimes comb out so many insects, their larvae and testicles that it is enough for a whole collection. But animals themselves, especially large ones, are not able to get rid of the “evil spirits”. Swimming doesn't help here, and they don't know how to rob each other like monkeys. And how many insects can you pull out with the help of a zebra’s hoof or a hippopotamus’ “suitcase” mouth?

Herons with an elephant and on a hippopotamus

Birds provide one more service to their charges: they alert them to danger. Seeing an enemy on the horizon, they take off and, screaming loudly, begin to circle above their “masters,” giving them a chance to escape. Such alliances are vitally beneficial to both parties.

COMMONWEALTH OF AQUATIC LIFE

Among sea ​​inhabitants There are real lovebirds who cannot exist without each other. A classic example of such a pair is the hermit crab and the adamsia sea anemone.

Cancer, having settled in the shell of a mollusk, immediately begins to take care of its protection. He is looking for sea anemone the right size, separates it from the substrate, carefully carries it in a claw to its house and sits it there.

At the same time, the sea anemone, which burns everyone who comes close to it with its poisonous tentacles, does not offer the slightest resistance to cancer! She seems to know that in the new place she will be much more satisfied: small pieces of prey that slipped out of the crayfish’s mouth will end up in her mouth. In addition, by “riding” the hermit crab, she will be able to move around, which means she can more quickly renew the water in her womb, which is vital for her. Cancer will now be protected from predators who want to profit from it.

So they live together until their death. If you remove an anemone from a crayfish's house, he will immediately put it back. If you remove the crayfish itself from the shell, the sea anemone will soon die, no matter how well it is fed.

CHAINED BY ONE CHAIN

The mystery of such “gravity” has not been fully solved, but it is certainly known that it is based on “benefit”: it is easier for animals of different species to preserve their lives by uniting in a kind of “commonwealth”. Just like people.

In nature, everything is interconnected, and not a single link can be touched without pain. biological system. I would like to hope that by mastering natural resources, people will take this into account.

Question 1. Define the main forms of interactions between living organisms.
1. Symbiosis (cohabitation)- a form of relationship in which both partners or one of them benefit from the interaction without causing harm to the other.
2. Antibiosis- a form of relationship in which both interacting populations (or one of them) experience a negative impact.
3. Neutrality- a form of relationship in which organisms living in the same territory do not directly influence each other. They form simple compounds.

Question 2. What forms of symbiosis do you know and what are their features?
There are several forms of symbiotic relationships, characterized by varying degrees partners' dependencies.
1. Mutualism- a form of mutually beneficial cohabitation, when the presence of a partner is a prerequisite for the existence of each of them. For example, termites and flagellated protozoa that live in their intestines. Termites cannot themselves digest the cellulose on which they feed, but flagellates receive nutrition, protection and a favorable microclimate; lichens, which represent the inseparable cohabitation of a fungus and an algae, when the presence of a partner becomes a condition of life for each of them. The hyphae of the fungus, entwining the cells and filaments of the algae, receive substances synthesized by the algae. Algae extract water and minerals from the fungal hyphae. Lichen fungi are not found in a free state and are capable of forming a symbiotic organism only with a certain type seaweed
Higher plants also enter into mutually beneficial relationships with fungi. Many grasses and trees develop normally only when soil fungi colonize their roots. The so-called mycorrhiza is formed: root hairs on plant roots do not develop, and the fungal mycelium penetrates into the root. Water and mineral salts plants receive from the fungus, and the fungus, in turn, receives carbohydrates and other organic substances.
2. Cooperation- mutually beneficial coexistence of representatives of different species, which is, however, mandatory. For example, hermit crab and sea anemone soft coral.
3. Commensalism(companionship) - a relationship in which one species benefits, but the other is indifferent. For example, jackals and hyenas, eating leftover food from large predators - lions; fish pilots.

Question 3. What is the evolutionary significance of symbiosis?
Symbiotic relationships allow organisms to most fully and effectively master their environment and are essential components natural selection, involved in the process of divergence of species.

Cohabitation of algae with other organisms T.V. Sedova.[...]

Plant cohabitation can occur without intravital metabolism. In these cases, a plant living on another, using the latter only as a place of attachment, is called an epiphyte. A special case of epiphytism are epiphytism, i.e. plants that use only the leaves of another plant as support. Epiphytes and epiphylls can significantly influence their substrate, complicating gas exchange in other ways.[...]

Symbiosis (cohabitation). This is a form of relationship in which both partners or one of them benefits from the other.[...]

All forms of cohabitation that occur between organisms belonging to different species are called symbioses. Between the above types of cohabitation there are many transitional forms, which makes the connections between organisms in the biosphere extremely diverse. The more diverse the connections that support the coexistence of species, the more stable their cohabitation.[...]

Symbiosis is the cohabitation of organisms of different species, from which both benefit.[...]

Mycorrhizal cohabitation (symbiosis) is mutually beneficial to both symbionts: the fungus extracts additional, inaccessible nutrients and water from the soil for the tree, and the tree supplies the fungus with the products of its photosynthesis - carbohydrates.[...]

Symbiosis, or cohabitation of two organisms, is one of the most interesting and is still in many ways mysterious phenomena in biology, although the study of this issue has a history of almost a century. The phenomenon of symbiosis was first discovered by the Swiss scientist Schwendener in 1877 while studying lichens, which, as it turned out, are complex organisms consisting of an algae and a fungus. The term “symbiosis” appeared in scientific literature later. It was proposed in 1879 by De Bary.[...]

Neutrality is the cohabitation of two species on the same territory, which has neither positive nor negative consequences for them. For example, squirrels and moose.[...]

SYMBIOSIS - close cohabitation of two or more organisms of different species, in which the organisms (symbionts) benefit each other. According to the degree of partnership and food dependence on each other, several types of symbiosis are distinguished: commensalism, mutualism, etc. Thus, commensalism (from the Latin “companion”) is a form of relationship between two species, when one feeds at the expense of the other, without causing any harm to it . Hermit crabs live with sea anemones; the latter attach to the mollusk shell in which the hermit crab lives, protecting it from enemies and feeding on the remains of its prey. Commensalism is especially widespread among sea ​​creatures leading a sedentary lifestyle.[...]

Symbiosis is a close cohabitation of two or more species, beneficial for partners.[...]

SYMBIOSIS [gr. symbiosis cohabitation] - long-term cohabitation of organisms of different species (symbionts), usually bringing them mutual benefit (for example, lichen - C. fungus and algae).[...]

Mutualism is a form of cohabitation of organisms in which both partners benefit (the same as symbiosis).[...]

Symbiosis (Greek symbiosis - cohabitation) - cohabitation of individuals of two species, when both partners enter into direct mutually beneficial interaction with external environment, which manifests itself for them in the form of one of the forms of adaptation to the conditions of existence.[...]

Since in synoikia cohabitation is indifferent for one of the partners and is useful only for the other partner, adaptations in this case are one-sided. As an example, we can point out that in mites of the family Tyroglyphidae, which use various insects for dispersal, a special hypopial phase (hypopus phase) arose between the nymph and deutonymph phases.[...]

Another example of symbiosis is the cohabitation of higher plants with bacteria, the so-called bacteriotrophy. Symbiosis with nodule bacteria-nitrogen fixers are widely distributed among legumes (93% of the studied species) and mimosa (87%). Thus, bacteria from the genus Lygolisni, living in nodules on the roots of leguminous plants, are provided with food (sugars) and habitat, and the plants receive from them in return an accessible form of nitrogen (Fig. 6.13).[...]

Shilova A. I., Kurazhkovskaya T. N. Cohabitation of Glyptotendipes varipes Goetgh. and bryozoans Plumatella fungosa Pall.[...]

There are also mycorrhizal fungi that cohabit with the roots of higher plants. The mycelium of these fungi envelops the roots of plants and helps obtain nutrients from the soil. Mycorrhiza is observed mainly in woody plants that have short sucking roots (oak, pine, larch, spruce).[...]

Mutualism is a mutually beneficial cohabitation when the presence of a partner becomes a prerequisite for the existence of each of them. An example is the cohabitation of nodule bacteria and leguminous plants, which can live together on soils poor in nitrogen and enrich the soil with it. [...]

Commensalism is a type of interspecific relationship, cohabitation, in which, in a joint environment, organisms of one species unilaterally benefit from the presence of organisms of another species (for example, “housing”, “transportation”, freeloading).[...]

Neutrality (from Latin - neither one nor the other) is the cohabitation of two populations of living organisms, when neither of them is influenced by the other. For example, species of herbivorous and predatory insects living in the same biocenosis do not related friend with another relationship of competition or nutrition. With neutralism, species are not directly related to each other, but can sometimes depend on the state of a given biocenosis as a whole. [...]

An example of a mutually beneficial relationship is the cohabitation of so-called nodule bacteria and leguminous plants (peas, beans, soybeans, clover, etc.). These bacteria, capable of absorbing nitrogen from the air and converting it into amino acids, settle in the roots of plants. The presence of bacteria causes the growth of root tissues and the formation of thickenings - nodules. Plants in symbiosis with nitrogen-fixing bacteria can grow on soils poor in nitrogen and enrich the soil with it. This is why legumes are introduced into agricultural crop rotation.[...]

Mutualism (obligate symbiosis) is a mutually beneficial cohabitation when either one of the partners or both cannot exist without a cohabitant. For example, herbivorous ungulates and cellulose-degrading bacteria.[...]

Mutualism (obligate symbiosis) is a mutually beneficial cohabitation when either one of the partners or both cannot exist without a cohabitant. For example, herbivorous ungulates and cellulose-degrading bacteria. Cellulose-degrading bacteria live in the stomach and intestines of herbivorous ungulates. They produce enzymes that break down cellulose, so they are essential for herbivores who do not have such enzymes. Herbivorous ungulates, for their part, provide bacteria with nutrients and habitat with optimal temperature, humidity, etc.[...]

A typical example symbiosis can serve as close cohabitation between fungi and algae, leading to the formation of a more complex and more adapted natural conditions plant organism- lichen. To others a shining example symbiotic cohabitation in the soil is the symbiosis of fungi with higher plants when fungi form m i-k o r i z u on the roots of plants. A clear symbiosis is observed between nodule bacteria and leguminous plants.[...]

Almost all types of trees in normal conditions cohabitate with mycorrhizal fungi. The mycelium of the fungus envelops the thin roots of the tree like a sheath, penetrating into the intercellular space. A mass of the finest mushroom threads, extending a considerable distance from this cover, successfully performs the function of root hairs, sucking up a nutrient soil solution. [...]

Mutualism is a symbiotic relationship when both cohabiting species benefit from each other. [...]

Firstly, a specific feature of lichens is the symbiotic cohabitation of two different organisms- heterotrophic fungus (mycobiont) and autotrophic algae (phycobiont). Not every cohabitation of a fungus and algae forms a lichen. Lichen cohabitation should be permanent and historically developed, and not random, short-term. In nature, there are cases when a fungus and an alga form a temporary mixed accumulation, but this is not yet a lichen. In a true lichen, a fungus and an alga enter into close relationship, the fungal component surrounds the algae and can even penetrate their cells.[...]

Commensalism (or “freeloading”) is a form of cohabitation in which one species lives off the food reserves of another, without bringing benefit in turn. Sometimes commensalism appears as a more or less random phenomenon and is almost completely imperceptible to the partner whose food supplies are devoured. So, for example, the Malayan beetle from the genus Hustrev Nore drills into the branches of trees and feeds on the juice protruding from the wounds, and the protruding juice also attracts flies (Mie-c1 c1ae) and some other insects, which eat it together with Huygiree.[...]

Using the example of European and partly allotropic insects, we see their mutually beneficial cohabitation in biocenoses with plants. Even closer symbiotic relationships have been noted between some insects and the yeasts and bacteria that inhabit their intestines (Werner, 1927; Hitz, 1927, etc.).[...]

A typical example of close symbiosis, or mutualism between plants, is the cohabitation of an algae and a fungus, which form a special integral lichen organism (Fig. 6.11).[...]

SYMBIOSIS - a type of relationship between organisms of different systematic groups- mutually beneficial cohabitation of individuals of two or more species, for example algae, fungi and microorganisms within the body of a lichen.[...]

In some cases, the body or structures of one species may serve as habitat or protection for another. For example, in coral reefs lives a large number of marine organisms. Small sea inhabitants settle in the body cavity of the echinoderm holothurian. Epiphytic plants (mosses, lichens, some flowering plants) settle on trees, using them only as a place of attachment, and feed by photosynthesis.[...]

Competition is one of the reasons that two species, slightly different in the specifics of nutrition, behavior, lifestyle, etc., rarely coexist in the same community. Here the competition is in the nature of direct hostility. The most severe competition with unforeseen consequences occurs if a person introduces animal species into communities without taking into account already established relationships.[...]

Lichens represent a kind of group complex organisms whose body always consists of two components - a fungus and an algae. Now every schoolchild knows that the biology of lichens is based on the phenomenon of symbiosis - the cohabitation of two different organisms. But just over a hundred years ago, lichens were a great mystery to scientists, and the discovery of their essence by Simon Schwendener in 1867 was assessed as one of the most amazing discoveries of that time.[...]

Moles are not kind to their neighbors and do not tolerate any residents or other moles in their burrows. And if they are put together in a cramped box, the strong will kill and eat the weak. Only when it is time to breed, usually in March - May, do the male and female cohabit for a short time. It is possible that the male stays with the children until they grow up, and even allegedly brings them worms and other food. And if there is a flood, he helps the mother drag the children to dry holes. But whether this is actually so is still unknown with accuracy.[...]

K. is used to study the migration routes of animals (especially birds), establish the boundaries of their habitats, the characteristics of seasonal biology, and solve other problems. COMBINED IMPACT - see art. Impact on environment. COMMENSALISM, or freeloading [from lat. sot - s and mensa - table, meal] - a type of cohabitation of organisms when one of them (commensal) constantly or temporarily exists at the expense of the other, without causing him harm. COMPENSATORY BEHAVIOR - a complex of behavioral reactions of organisms aimed at weakening (compensation) of the limiting influence environmental factor.[ ...]

Commensalism is an interspecific interaction between organisms in which one organism benefits at the expense of another without harming it, while the other organism has neither benefit nor harm from this interaction. For example, some types of marine polyps settle on the surface of the body large fish, feeding on their secretions, but for fish this cohabitation is indifferent, that is, it has no meaning.[...]

The first roots of marattiaceae are usually infected with the fungus. But mycorrhiza is facultative here, since the fern can develop normally without interaction with the fungus, and this cohabitation is not vital for them.[...]

Mutualism is a widespread form of mutually beneficial relationships between species. Lichens are a classic example of mutualism. Symbionts in a lichen - a fungus and an alga - physiologically complement each other. The hyphae of the fungus, entwining the cells and filaments of the algae, form special suction processes, haustoria, through which the fungus receives substances assimilated by the algae. Algae obtains its minerals from water. Many grasses and trees normally exist only in cohabitation with soil fungi that settle on their roots. Mycorrhizal fungi promote the penetration of water, minerals and organic substances from the soil into plant roots, as well as the absorption of a number of substances. In turn, they receive carbohydrates and other organic substances necessary for their existence from the roots of plants.[...]

A fairly common phenomenon in relationships between different species is symbiosis, or the coexistence of two or more species, in which none of them can live separately under given conditions. A whole class of symbiotic organisms is represented by lichens - fungi and algae living together. In this case, the lichen fungus, as a rule, does not live at all in the absence of algae, while most of the algae that make up lichens are also found in free form. In that mutually beneficial cohabitation the fungus supplies the algae with water and minerals, and the algae supplies the fungus with photosynthetic products. This combination of properties makes these symbiotic organisms extremely unpretentious to living conditions. They are able to settle on bare stones, on the bark of trees, etc. At the same time, the fact that lichens obtain a significant part of the mineral substances necessary for life from dust settling on their surface makes them very sensitive to the content of toxic substances in the air. One of the most reliable methods for determining the level of toxicity of impurities contained in the air is taking into account the number and species diversity of lichens in the controlled area, lichen indication. [...]

It is a rare animal that is so little scrupulous in choosing a home and its environment as the kuzulis. And the crowns of hundred-meter eucalyptus trees are suitable for him, and low-growing bushes, and dense rainforests, and rare groves along river valleys, and crevices in bare rocks, and holes in river cliffs, and rabbit holes in the open steppe, and even attics. Because male cousulis often settle in rabbit holes in Central Australia, an absurd legend was born. Farmers assure that this choice of housing was made by the old sinners for a reason: as if they were in a criminal misalliance with the rabbits. And it’s as if they saw crosses from their cohabitation. But this is a myth.[...]

A population (from the Latin populie - population) is a collection of individuals of the same species that inhabit a certain space for a long time, have a common gene pool, the ability to interbreed freely, and are to one degree or another isolated from other populations of this species. Population is the elementary form of existence of a species in nature. Populations evolve and are the units of species evolution and speciation. Possessing all the characteristics of a biological system, a population, nevertheless, is a collection of organisms, as if isolated from the natural system, since in nature, individuals of one species always coexist with individuals of other species. Only in artificial conditions or in a special experiment is it possible to deal with a “pure” population, for example, a culture of microorganisms, plant sowing, animal offspring, etc. [...]

Life on poor soils has developed a number of adaptations in heathers, the most important of which is symbiosis with fungi in the form of mycorrhiza. The lint of almost all heathers is closely entwined with mushroom threads, supplying them with nutrients from humus. In the latter case, some simple fungi (the body of which consists of only a few cells) live entirely in the cells of the heather roots and are gradually digested by them. Mycorrhiza has a huge positive value in the life of heathers. In some cases (for example, in the strawberry tree - Arbutus, Table 13), infected roots turn into pear-shaped nodules (mycodomathia), the epidermal cells of which are transformed into root hairs. It has been established that heather seeds, for example, germinate only with the help of mycorrhiza. Some researchers believe that heathers live on acidic soils because the fungi that cohabit with them cannot tolerate alkaline soils.