Algae names 3. Life cycles of algae. The role of algae in nature and human life. Types of algae - names and photos. Types of brown algae

The division of organisms, considered here as algae, is very diverse and does not represent a single taxon. These organisms are heterogeneous in their structure and origin.

Algae are autotrophic plants; their cells contain various modifications of chlorophyll and other pigments that provide photosynthesis. Algae live in freshwater and marine, as well as on land, on the surface and in the soil, on the bark of trees, stones and other substrates.

Algae belong to 10 divisions from two kingdoms: 1) Blue-green, 2) Red, 3) Pyrophyte, 4) Golden, 5) Diatoms, 6) Yellow-green, 7) Brown, 8) Euglena, 9) Green and 10 ) Charovye. The first section belongs to the kingdom of Prokaryotes, the rest - to the kingdom of plants.

Department of Blue-green algae, or Cyanobacteria (Cyanophyta)

There are about 2 thousand species, united in about 150 genera. These are the oldest organisms, traces of which were found in the Precambrian deposits, their age is about 3 billion years.

Among the blue-green algae, there are unicellular forms, but most of the species are colonial and filamentous organisms. They differ from other algae in that their cells do not have a formed nucleus. They lack mitochondria, vacuoles with cell sap, there are no formalized plastids, and the pigments with which photosynthesis is carried out are located in photosynthetic plates - lamellae. The pigments of blue-green algae are very diverse: chlorophyll, carotenes, xanthophylls, as well as specific pigments from the phycobilin group - blue phycocyanin and red phycoerythrin, which are found in addition to cyanobacteria only in red algae. The color of these organisms is most often blue-green. However, depending on the quantitative ratio of various pigments, the color of these algae can be not only blue-green, but also purple, reddish, yellow, pale blue or almost black.

Blue-green algae are found around the globe and are found in a wide variety of conditions. They are able to exist even in extreme living conditions. These organisms endure prolonged darkening and anaerobiosis, can live in caves, in different soils, in layers of natural silt rich in hydrogen sulfide, in thermal waters, etc.

Around the cells of colonial and filamentous algae, mucous sheaths are formed, which serve as a protective wrapping that protects the cells from drying out and serves as a light filter.

Many filamentous blue-green algae have peculiar cells - heterocysts. These cells have a well-defined bilayer membrane, and they look empty. But these are living cells filled with transparent contents. Blue-green algae with heterocysts are able to fix atmospheric nitrogen. Some types of blue-green algae are components of lichens. They can be found as symbionts in the tissues and organs of higher plants. Their ability to fix atmospheric nitrogen is used by higher plants.

The massive development of blue-green algae in water bodies can have negative consequences. Increased and pollution of waters by organic substances cause the so-called "water bloom". This makes the water unfit for human consumption. Some freshwater cyanobacteria are toxic to humans and animals.

Reproduction of blue-green algae is very primitive. Unicellular and many colonial forms reproduce only by dividing cells in half. Most filamentous forms reproduce by hormogonies (these are short sections, separated from the maternal filament, growing into adults). Reproduction can also be carried out with the help of spores - overgrown thick-walled cells that are able to survive adverse conditions and then grow into new threads.

Division Red algae (or Bagryanka) (Rhodophyta)

Red algae () - a large (about 3800 species from more than 600 genera) group mainly marine life... Their sizes vary from microscopic to 1-2 m. Outwardly, red algae are very diverse: there are threadlike, lamellar, coral-like forms, dissected and branched to varying degrees.

Red algae have a peculiar set of pigments: in addition to chlorophyll a and b, there is chlorophyll d, known only for this group of plants, there are carotenes, xanthophylls, as well as pigments from the phycobilin group: blue pigment - phycocyanin, red - phycoerythrin. Various combinations of these pigments determine the color of the algae - from bright red to bluish-green and yellow.

Red algae reproduce vegetatively, asexually and sexually. Vegetative reproduction is typical only for the lowest organized purple flies (unicellular and colonial forms). In highly organized multicellular forms, the torn off sections of the thallus die. Various kinds of spores serve for asexual reproduction.

The sexual process is oogamous. On the gametophyte plant, male and female sex cells (gametes), devoid of flagella, are formed. During fertilization, female gametes are not released into the environment, but remain on the plant; male gametes are thrown out and passively carried by currents of water.

Diploid plants - sporophytes - have the same appearance as gametophytes (haploid plants). This is an isomorphic generational change. The organs of asexual reproduction are formed on sporophytes.

Many red algae are widely used by humans and are edible and healthy. In the food and medical industry is widely used derived from different types purple (about 30) polysaccharide agar.

Department Pyrrophyta (or Dinophyta) algae (Pyrrophyta (Dinophyta))

The department includes about 1200 species from 120 genera, uniting eukaryotic unicellular (including biclagellate), coccoid and filamentous forms. The group combines the characteristics of plants and animals: some species have tentacles, pseudopodia, and stinging cells; some have the characteristic of animals type of food provided by the pharynx. Many have stigma, or peephole. The cells are often covered with a hard shell. Chromatophores of brownish and reddish shades, contain chlorophylls a and c, as well as carotenes, xanthophylls (sometimes phycocyanin and phycoerythrin). Starch is deposited as reserve substances, sometimes oil. Flagellate cells have distinct dorsal and ventral sides. There are grooves on the cell surface and in the pharynx.

Propagate by division in a mobile or stationary state (vegetatively), zoospores and autospores. Sexual reproduction is known in few forms; it takes place in the form of a fusion of isogametes.

Pyrophyte algae are common inhabitants of polluted water bodies: ponds, sedimentation tanks, some reservoirs and lakes. Many form phytoplankton in the seas. Under unfavorable conditions, cysts with thick cellulose membranes are formed.

The most widespread and species-rich genus is Cryptomonas.

Division Golden algae (Chrysophyta)

Microscopic or small (up to 2 cm in length) organisms of a golden yellow color that live in salt and fresh water bodies around the globe. There are unicellular, colonial and multicellular forms. In Russia, about 300 species from 70 genera are known. Chromatophores are usually golden yellow or brownish. They contain chlorophylls a and c, as well as carotenoids and fucoxanthin. Chrysolaminarin and oil are deposited as reserve substances. Some species are heterotrophic. Most forms have 1–2 flagella and are therefore mobile. They reproduce mainly asexually - by division or by zoospores; the sexual process is known only in a few species. They are usually found in clean fresh waters (acidic waters of sphagnum bogs), less often in the seas and in soils. Typical phytoplankton.

Department of Diatoms (Bacillariophyta (Diatomea))

Diatoms (diatoms) number about 10 thousand species belonging to about 300 genera. These are microscopic organisms that live mainly in water bodies. Diatoms are a special group of unicellular organisms, different from other algae. Diatom cells are covered with a silica shell. The cell contains vacuoles with cell juice. The core is located in the center. Chromatophores are large. Their color has various shades of yellow-brown color, since carotenes and xanthophylls, which have yellow and brown shades, and masking chlorophylls a and c, prevail among the pigments.

The diatom shells are characterized by geometric regularity of the structure and a wide variety of outlines. The carapace consists of two halves. The large - epithecus - covers the smaller - the hypothesis, like the lid covers the box.

Most diatoms with bilateral symmetry are able to move along the surface of the substrate. The movement is carried out using a so-called seam. The seam is a slit that cuts through the sash wall. The movement of the cytoplasm in the gap and its friction against the substrate ensure the movement of the cell. The cells of diatoms with radial symmetry are incapable of movement.

Diatoms usually reproduce by dividing the cell into two halves. The protoplast increases in volume, as a result of which the epithecus and hypothesis diverge. The protoplast is divided into two equal parts, the nucleus is mitotically divided. In each half of the split cell, the shell plays the role of an epithecus and completes the missing half of the shell, always a hypothesis. As a result of numerous divisions, a gradual decrease in cell size occurs in a part of the population. Some cells are about three times smaller than the original cells. Having reached their minimum size, the cells develop auxospores ("growing spores"). The formation of auxospores is associated with the sexual process.

The cells of diatoms in the vegetative state are diploid. Before sexual reproduction, a reduction nuclear fission (meiosis) occurs. Two diatom cells approach each other, the valves move apart, the haploid (after meiosis) nuclei merge in pairs, and one or two auxospores are formed. The auxospore grows for some time, and then develops a shell and turns into a vegetative individual.

Among the diatoms, there are light-loving and shade-loving species; they live in reservoirs at different depths. Diatoms can also live in soils, especially wet and swampy. Diatoms, along with other algae, can cause snow to bloom.

Diatoms play an important role in the economics of nature. They serve as a permanent food source and an initial link in the food chain for many aquatic organisms. Many fish feed on them, especially juveniles.

The shells of diatoms, settling to the bottom for millions of years, form a sedimentary geological rock - diatomite. It is widely used as a building material with high heat and sound insulation properties, as filters in the food, chemical and medical industries.

Department of yellow-green algae (Xanthophyta)

This group of algae has about 550 species. These are mainly inhabitants of fresh waters, less often found in the seas and on wet soil. Among them are unicellular and multicellular forms, flagellate, coccoid, filamentous and lamellar, as well as siphonal organisms. These algae are characterized by a yellow-green color, which gave the name to the entire group. Chloroplasts are disc-shaped. Typical pigments are chlorophylls a and c, a and b carotenoids, xanthophylls. Spare substances - glucan,. Sexual reproduction is oogamous and isogamous. Reproduce vegetatively by division; asexual reproduction is carried out by specialized mobile or immobile cells - zoo- and aplanospores.

Division Brown algae (Phaeophyta)

Brown algae are highly organized multicellular organisms that live in the seas. There are about 1500 species from about 250 genera. The largest of brown algae reach several tens of meters (up to 60 m) in length. However, this group also includes species of microscopic size. The shape of the thallus can be very diverse.

A common feature of all algae belonging to this group is a yellowish-brown color. It is caused by the pigments carotene and xanthophyll (fucoxanthin, etc.), which mask the green color of chlorophylls a and c. The cell wall is cellulose with an outer pectin layer capable of strong mucousiness.

All forms of reproduction are found in brown algae: vegetative, asexual and sexual. Vegetative reproduction occurs by detached parts of the thallus. Asexual reproduction is carried out using zoospores (mobile due to the flagella of the spores). The sexual process in brown algae is represented by isogamy (less often - anisogamy and oogamy).

In many brown algae, the gametophyte and sporophyte differ in shape, size, and structure. In brown algae, there is an alternation of generations, or a change in nuclear phases in the development cycle. Brown algae are found in all seas of the world. In the thickets of brown algae near the coast, numerous coastal animals find shelter, breeding and feeding grounds. Brown algae are widely used by humans. Alginates (salts of alginic acid) are obtained from them, which are used as stabilizers of solutions and suspensions in the food industry. They are used in the manufacture of plastics, lubricants, etc. Some brown algae (kelp, alaria, etc.) are used in food.

Department of Euglenophyta (Euglenophyta)

This group contains about 900 species from about 40 genera. These are unicellular flagellate organisms, mainly inhabitants of fresh waters. Chloroplasts contain chlorophylls a and b and a large group of auxiliary pigments from the carotenoid group. In these algae, photosynthesis occurs in the light, and in the dark they switch to heterotrophic nutrition.

Reproduction of these algae occurs only due to mitotic cell division. Their mitosis differs from this process in other groups of organisms.

Department of Green Algae (Chlorophyta)

Green algae are the largest department of algae, with, according to various estimates, from 13 to 20 thousand species from about 400 genera. These algae are characterized by a pure green color, like in higher plants, since chlorophyll predominates among the pigments. Chloroplasts (chromatophores) contain two modifications of chlorophyll a and b, as in higher plants, as well as other pigments - carotenes and xanthophylls.

The rigid cell walls of green algae are formed by cellulose and pectin substances. Spare substances - starch, less often oil. Many features of the structure and life of green algae testify to their relationship with higher plants. Green algae are distinguished by the greatest diversity in comparison with other departments. They can be unicellular, colonial, multicellular. This group includes all the variety of morphological differentiation of the body known for algae - monadic, coccoid, palmeloid, filamentous, lamellar, noncellular (siphonal). The range of their sizes is wide - from microscopic single cells to large multicellular forms tens of centimeters long. Reproduction is vegetative, asexual and sexual. All the main types of changes in developmental forms are encountered.

Green algae live more often in fresh water bodies, however, there are many salty and marine forms, as well as extra-aquatic terrestrial and soil species.

The most primitive representatives of green algae belong to the Volvox class. Usually these are unicellular organisms with flagella, sometimes united in colonies. They are mobile throughout their lives. Distributed in shallow fresh water bodies, swamps, in the soil. Among unicellular organisms, species of the genus Chlamydomonas are widely represented. The spherical or ellipsoidal cells of Chlamydomonas are covered with a membrane consisting of hemicellulose and pectin substances. There are two flagella at the anterior end of the cell. The entire inner part of the cell is occupied by a cupped chloroplast. The nucleus is located in the cytoplasm that fills the cup-shaped chloroplast. There are two pulsating vacuoles at the base of the flagella.

Asexual reproduction occurs with the help of biflagellated zoospores. During sexual reproduction in the cells of chlamydomonas, biflagellate gametes are formed (after meiosis).

Chlamydomonas species are characterized by iso-, hetero- and oogamy. When unfavorable conditions occur (drying up of the reservoir), Chlamydomonas cells lose their flagella, become covered with a mucous sheath and multiply by division. When favorable conditions occur, they form flagella and move to a mobile lifestyle.

Along with the autotrophic method of nutrition (photosynthesis), Chlamydomonas cells are able to absorb organic substances dissolved in water through the membrane, which contributes to the processes of self-purification of polluted waters.

Colonial cells (pandorina, volvox) are built like chlamydomonas.

In the Protococcal class, the main form of the vegetative body is immobile cells with a dense membrane and colonies of such cells. Chlorococcus and chlorella are examples of unicellular protococci. Asexual reproduction of Chlorococcus is carried out with the help of biflagellated motile zoospores, and the sexual process is the fusion of motile biflagellated isogametes (isogamy). Chlorella has no mobile stages during asexual reproduction, there is no sexual process.

The Ulotrix class combines filamentous and lamellar forms that live in fresh and marine waters. Ulotrix is \u200b\u200ba thread up to 10 cm long that attaches to underwater objects. The filament cells are identical, short-cylindrical, with lamellar wall chloroplasts (chromatophores). Asexual reproduction is carried out by zoospores (motile cells with four flagella).

The sexual process is isogamous. Gametes are mobile due to the presence of two flagella in each gamete.

The class Conjugates (couplers) combines unicellular and filamentous forms with a peculiar type of sexual process - conjugation. Chloroplasts (chromatophores) in the cells of these algae are of the lamellar type and are very diverse in shape. In ponds and in reservoirs with a slow current, the bulk of green mud is formed by filamentous forms (spirogyra, zignema, etc.).

When conjugated from opposite cells of two adjacent filaments, processes grow that form a channel. The contents of two cells merge, and a zygote is formed, which is covered with a thick membrane. After a dormant period, the zygote germinates, giving rise to new filamentous organisms.

The Siphon class includes algae with a non-cellular structure of the thallus (thallus) with its rather large size and complex dissection. The caulerpa sea siphon algae looks like a leafy plant: its size is about 0.5 m, it is attached to the ground by rhizoids, its thalli spread over the ground, and vertical formations resembling leaves contain chloroplasts. It easily reproduces vegetatively by parts of the thallus. In the body of the alga there are no cell walls, it has a continuous protoplasm with numerous nuclei, and chloroplasts are located near the walls.

Department of Charophyta (Charophyta)

These are the most complex algae: their body is differentiated into nodes and internodes, in the nodes there are whorls of short branches resembling leaves. The size of plants is from 20-30 cm to 1-2 m. They form solid thickets in fresh or slightly salted water bodies, attaching to the ground by rhizoids. Outwardly, they resemble higher plants. However, these algae do not have a real dissection into root, stem and leaves. There are about 300 species of chara algae belonging to 7 genera. They have similarities with green algae in the composition of pigments, cell structure, and reproduction characteristics. There is a similarity with higher plants in the features of reproduction (oogamy), etc. The noted similarity indicates the presence of a common ancestor in charoche and higher plants.

Vegetative propagation of charots is carried out by special structures, the so-called nodules, formed on the rhizoids and on the lower parts of the stems. Each of the nodules easily germinates, forming a protonema, and then a whole plant.

The entire department of algae after the first acquaintance with it is very difficult to grasp mentally and to give each department its correct place in the system. The system of algae was developed in science not soon and only after many unsuccessful attempts. At the present time, we present to any system the basic requirement that it be phylogenetic. At first it was thought that such a system could be very simple; imagined it in the form of one family tree, even if with many side branches. Now we are building it only in the form of many genealogical lines that developed in parallel. The matter is further complicated by the fact that, along with progressive changes, there are also regressive ones, which pose a difficult task for solution - in the absence of this or that sign or organ, decide that it has not yet appeared or has already disappeared?

The system given by Ville in the 236th edition of the main work on descriptive taxonomy of plants, edited by A. Engler, was considered the most perfect for a long time. The main group here are flagellate organisms or Flagellata.

This scheme embraces only the main group of green algae. For the rest, we will take Rosen's scheme, changing only the names of the groups, in accordance with those adopted above when describing them.

The oceans are an endless source of amazing animals and plants, among which various algae occupy an important place. The report will focus on the representative of the marine flora - brown algae.

Types of brown algae

Brown seaweed - multicellular organisms. They live in sea water at a depth of 5 to 100 meters. They are usually attached to stones. The brown color of algae is given by a special brown pigment. Some types of algae are striking in their size, reaching a length of up to 60 meters, there are also very tiny representatives. Inhabits the world's oceans more than 1000 types brown-green algae.

From the vast class of brown algae, several interesting and useful species for humans can be distinguished.

1. Sargasso

The Sargasso Sea got its name due to the accumulation of floating brown seaweed in its waters - sargasso. Huge masses of these algae float on the surface of the water and form a continuous carpet. Because of this feature of brown algae in ancient times, the Sargasso Sea was notorious - it was believed that a ship could get entangled in algae and could not sail further, and if sailors climbed into the water to untangle the ship, they would get entangled and drown themselves.

In fact, the legends and myths about the Sargasso Sea are not true, because the Sargassos are absolutely safe and do not interfere with the movement of ships.

Sargassos are used:

• as a source of potassium;
• the stalks of these algae are food and shelter for their young.

2. Fucus

Other names are sea grapes, seaweed king. Fucus is common in almost all marine reservoirs of the Earth. It lives at shallow depths in the form of small bushes with long greenish-brown leaves. Fucus is a storehouse of vitamins and nutrients.

Used by:

• in medicine for the treatment and prevention of various diseases and strengthening the immune system;
• helps to care for skin and hair, is used as a weight loss supplement.

3. Laminaria

Other names for kelp - seaweed. It looks like a long brown-green stem with leaves. This algae lives in the Black, Red, Japanese and other seas. The chemical composition of algae is rich in vitamins, minerals, amino acids. Eaten only 2 types of kelp - Japanese and sugary.

Using:

• Inedible varieties are widely used in medicine.
• Like fucus, kelp is used in various diets as a natural appetite suppressant.
• Kelp contains special substances that can protect the human body from dangerous radiation exposure.
• Also, seaweed is used to treat cancer and leukemia.

With the constant use of kelp, you can reduce the level of cholesterol in the blood, improve the functioning of the intestines, increase the protective properties of immunity, normalize metabolism, and improve the work of the nervous, circulatory and respiratory systems.

Brown algae - sea \u200b\u200bplants, which are widely used in many areas of human activity.

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Algae play a huge role in nature and human life. First, they are active participants in the circulation of substances in natural environment (the simplest unicellular species).

Secondly, irreplaceable natural sources vital trace elements (vitamins, minerals). They are also used in medicine, cosmetology, food industry and other industries.

Difficult conditions are not required for their breeding, and they grow at a depth of several meters to 40-100.

Life Cycles algae have several stages of flow - depending on the complexity of the structure. The same is with the ability to reproduce.

What species, groups, names exist, in which sea algae are cultivated, photographs and other interesting information - about this in this article.

Description

Algae, unlike plants, grow in an aquatic environment (although there are plants that live in a similar environment). There are also soil, rocky representatives.

Life in water has relative stability: the presence of liquid, constant illumination and temperature, as well as a number of other advantages. As a consequence, each cell that is a constituent part of the alga is identical to the rest. Therefore, these aquatic "plants" (conventional name) practically do not have any pronounced features in their appearance (except for some, more "highly developed").

Basically, algae live in coastal areas of the seas - rocky shores, less often - sand or pebbles. The maximum height at which these aquatic "plants" can live are surfaces slightly wetted by sea drops (an example of almost planktonic - sargassus), the minimum is a few meters deep (an example of deep-water ones - red).

There are algae that live in tidal bodies of rocky surfaces. But such species of marine life must withstand the absence of moisture, variable temperature and salinity.

Algae are used in medicine, agronomy (soil fertilization), food production for humans, industry, and so on.

Body

Algae in their structure consists of one or many cells.

This is a unified system, which is the same type of cells stacked on top of each other. There may be dissection, but the presence of vegetative organs and other parts of the body of this aquatic "plant" is excluded.

The appearance of algae is slightly similar to terrestrial non-woody plants.

The algae body consists of:

• thallus (thallus);
• trunk (may or may not be present);
• captures (for fastening to surfaces - rocks, bottom, other similar plants);
• hitching.

Types of algae

There are a huge number - from unicellular to complex (resembling higher plants). There are also different sizes - huge (up to 60 meters) and microscopic.

In total, there are about 30,000 species of algae. They are subdivided into the following departments:

• blue-eyed;
• prochlorophytic;
• cryptophyte;
• red;
• golden;
• dinophytic;
• diatoms;
• brown;
• green;
• yellow-green;
• euglena;
• charovye.

Also, the division is carried out into the following groups of algae (according to the degree of complexity of the structure):

• amoeba-like (examples: golden, yellow-green, pyrophytic);
• with a monadic structure - unicellular, move thanks to flagella, some have an intracellular primitive structure (examples of algae: green, yellow-green, golden, euglena, pyrophytic);
• with a coccoid structure - unicellular, without any organelles, form colonies;
• with a palmeloid structure - a combination of several coccoids into a common mass, are large, attached to the substrate;
• with a filamentous structure - these are already transitional from unicellular to multicellular algae, outwardly similar to a branched thread;
• with a lamellar structure - multicellular, which are formed from filaments that are combined with subsequent layering in various planes, forming plates (there are single-layer and multi-layer);
• with a siphonal structure - they consist of a multinucleated giant cell, similar to branching threads and balls.

Names and photos

Types of algae in the images:

1. Unicellular - consist of a cell, a nucleus and flagella (attachments). They can only be seen under a microscope.
   

   

2. Multicellular - kelp, which are known to humans as "seaweed".

   

Life cycle



In algae, development occurs according to a cycle or cyclomorphosis (this depends on the complexity of the structure of the aquatic "plant" and, accordingly, the mode of reproduction).

Algae that do not have (or have in exceptional cases) the ability to reproduce sexually, due to development, only change the structure of the body. The concept of cyclomorphosis is applicable to such aquatic plants (examples of algae: hyella, blue-green, glenodinium).

Cyclomorphosis is characterized by a high degree of plasticity. The passage of the stages depends largely on the ecological conditions of the environment. The manifestation of strictly all stages of cyclomorphosis does not always occur, some may even "drop out" from the general sequence.

Strict passage through all stages of the life cycle of algae (in the diagram above) is observed exclusively in those aquatic plants that occupy the upper stage of evolution (for example, brown ones).

Brown algae



These are multicellular aquatic "plants" that belong to ochrophytes. The name comes from the color of the pigment substance contained in chromatophores: green (which means the ability to photosynthesis), as well as yellow, orange and brown, which, when mixed, form a brownish tint.

They grow at depths of 6-15 and 40-100 meters in all marine reservoirs of the world.

Brown algae, in comparison with others, have more complex structure: they have a similarity of organs and different tissues in the body.

Cell surfaces are composed of a cellulose-gelatinous substance, which contains proteins, salts, carbohydrates.

Each algae cell has a nucleus, chloroplasts (in the form of discs), and a nutrient (polysaccharide).

Life cycle of brown algae

In this group of aquatic "plants", several types of growth are distinguished: through the top or by cell division.

Brown sexually and asexually. This means that some of them are recreated by fragmentation of their little body (thallus), the formation of the so-called kidneys, or through spores.

Zoospores have flagella and are mobile. And they also give a gametophyte, due to which sex cells are formed.



There are gametes derived from the sporophyte and having eggs and spermatozoa in the haploid stage.

Moreover, these aquatic "plants" emit pheromones, which contributes to the "meeting" of male and female germ cells.

Thanks to all these processes, the alternation of generations occurs in brown algae.

The use of brown algae

The most popular member of this group is kelp, or "seaweed". This algae grows along the coast, forming thickets. The composition of kelp contains a fairly large amount of macro- and microelements vital for humans, the most important of which is iodine. Besides food, it is also used as a soil fertilizer.

Also brown algae is used in medicine and in the manufacture of cosmetics.

Characteristics of unicellular algae

These species of aquatic "plants" are independent system, which is able to grow and develop, as well as self-replicate.

In terms of size, it is a microscopic algae (not visible to the naked eye), which in fact can be considered a “factory” for the extraction of useful raw materials: through the process of absorbing carbon dioxide and mineral salts from the environment, with their subsequent processing into proteins, fats and carbohydrates.

The life support products of unicellular algae are oxygen and carbon dioxide, which allows them to be active participants in the natural cycle.

Algae farming

In which of the seas is the widest cultivation of these sea "plants" carried out? According to the reference data, the maximum amount of algae is found in the White Sea. On the shore there is the village of Rebolda (in the region of Solovetsky Island), where they are engaged in the extraction and preparation of these water gifts.

There are 2 types of brown algae here: the famous kelp and fucus ("sea grapes").

In addition to eating, these "plants" are used to make biologically active substances that are used in medicine. These are very useful preparations, since they contain environmentally friendly White Sea algae.

Such products lower blood cholesterol levels, improve the functioning of the thyroid gland, prevent the development of age-related diseases associated with blood vessels, and so on. "Sea grapes" are good for treating problems with varicose veins, cellulite, and wrinkles.

Role in nature and human life

Algae are studied by a specialized science - algology (or ficology), which is a branch of botany.

The collection of information about these aquatic "plants" is necessary for solving such important problems: general biological problems; household tasks and so on.

This science is developing in the following areas:

1. The use of algae in medicine.
2. Use in solving environmental issues.
3. Accumulation of information about algae in order to solve other problems.

These marine "plants" are currently both living in natural reservoirs and grown on special farms.

• Seaweed, as food and not only, is popular in many countries of the world: Indonesia (annual collection of 3-10 million tons), Philippines, Japan, China, Korea, Thailand, Taiwan, Cambodia, Vietnam, Peru, Chile, England, USA ( California) and others.
• A new food product has now been discovered in the Philippines - noodles from seaweed (contains calcium, magnesium, iodine).
• Many favorite Japanese seaweed nori, which are dried by leaves and look like square thin plates, are applicable in the manufacture of sushi, rolls, for soups.
• In Wales, the popular laver bread is made from oats and red algae laver.
• Food gelatin, additives, alginates (dressings used in dentistry) are made from algae.
• Agar produced from these aquatic "plants" is used in the preparation of confectionery, desserts, drinks, meat dishes.
• Algae concentrates are used in weight loss products. Also included in toothpastes, cosmetics and paints.
• Alginates are used in industry (paper coatings, paints, gels, glue, textile printing).

Summary

The types of algae considered in the article (with a photo), names, groups, breeding and application only indicate that these are really important components not only of nature, but also of many aspects of human life (health, beauty, industrial raw materials, food, and so on) ... Without them, there would be no notorious "seaweed", marmalade, sushi and other such familiar dishes.

At first glance, it may seem that these simple natural "plants" are primitive (in their structure, life cycle) algae, but in reality everything is different. It turns out that even these aquatic "plants" have sexual reproduction, emit pheromones and support the circulation of substances in nature.

Algae report will tell you about what algae are, and what is the role of algae in nature and human life.

Algae message

Algae live in almost every body of water. They are a wayward indicator of the purity of water and supply it with oxygen, useful for all aquatic life.

What is algae?

Algae belong to an ecological heterogeneous group of multicellular phototrophic, unicellular, and colonial organisms, which, as a rule, live in water bodies. Everything known species algae among themselves are united by the following signs:

1.characterized by photoautotrophic nutrition and the presence of chlorophyll

2.there is no differentiation of the plant body into organs as such

3.algae have a pronounced conducting system

4.have a humid environment

5.No integumentary membrane

Due to the fact that algae are adapted to the aquatic environment, they have developed a special feature of physiology - the necessary nutrients absorbed by the entire surface of the plant's body. The vital activity of algae depends on four factors - light, carbon dioxide, chemical composition water and its temperature.

What are the types of algae?

In nature, algae are of three main types:

* Green algae

Belong to the division of lower plants, which have different morphological structure and sizes. They contain carotenoids and chlorophyll plates. Green algae come in multicellular and unicellular forms. They have a reserve substance - starch, sometimes oils. It is noteworthy that unicellular green algae live not only in the aquatic environment, but also in soil or snow. But multicellular plants live in the upper layers of water bodies, which is due to the implementation of the productive process of photosynthesis.

* Brown algae

They belong to the department of ochrophytic algae. Modern biology has more than 2000 species. Almost all brown algae live in the marine aquatic environment. And only 6 species of these plants were able to adapt to life on dry land in the course of evolution. Scientists have found that the chromatophores of brown algae contain fucoxanthin, a special pigment that stains them brown.

The most common brown algae are: Macrocystis Laminaria and Cystoseira. Chlorophyll is practically absent in their bodies, which makes the vital activity of these algae independent of the processes of photosynthesis. Therefore, the plant habitat is the seabed.

* Red algae

Red algae belong to the group of algae that contain in their body a specific red pigment - phycoerythrin. The color of the plant depends on the amount of phycoerythrin in the body of the plant - it ranges in color from a pronounced pink to dark cherry color.

Red algae are predominantly found in the seas. Their body carries out photosynthesis, despite the small amount of chlorophyll. These plants are widely used in industrial production, most of them are suitable for consumption.

Report on the importance of algae in nature and human life

1. Algae is the basis of food for herbivorous animals such as crustaceans, molluscs, some fish, mammals and others.

2. Algae enrich the water column with oxygen and the air above it. Dead plants of some species are capable of forming sedimentary rocks: diatomite, limestone and tripoli. They contribute to the process of soil formation and increase soil fertility. Algae living in the bottom area are a refuge and home for fish and other aquatic animals.

3. Algae are used by humans for food. Also bromine, iodine, agar-agar are extracted from them, medications are made.

4. They are used for biological water purification and act as fertilizer.

5. Kelp is widely used in the chemical, food, paper and textile industries.

In addition to beneficial properties, some types of algae are harmful. For example, unicellular algae, massively multiplying in fresh water bodies, lead to “water bloom. Living in sluices and water filters, they interfere with their normal operation.

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Chloroplasts are contained. Algae come in different shapes and sizes. They live mostly in water to depths where light penetrates.

Among the algae there are both microscopically small and gigantic ones, reaching lengths over 100 m (for example, the length of the brown algae macrocystis pear-shaped is 60-200 m).

The cells of algae contain special organoids - chloroplasts, which carry out photosynthesis. They have different shapes and sizes in different species. Mineral salts and carbon dioxide necessary for photosynthesis are absorbed by algae from the water throughout the entire surface of the body and oxygen is released into the environment.

In freshwater and marine water bodies, multicellular algae are widespread. The body of multicellular algae is called the thallus. A distinctive feature of the thallus is the similarity of cell structure and the absence of organs. All thallus cells are structured almost the same, and all parts of the body perform the same functions.

Algae reproduce asexually and sexually.

Asexual reproduction

Unicellular algae reproduce, as a rule, by division. Asexual reproduction of algae is also carried out by means of special cells - spores, covered with a membrane. Spores of many species have flagella and are able to move independently.

Sexual reproduction

Sexual reproduction is also characteristic of algae. In the process of sexual reproduction, two individuals participate, each of which passes on its chromosomes to the offspring. In some species, this transfer is carried out during the fusion of the contents of ordinary cells, in others, special germ cells - gametes - stick together.

Algae live mainly in water, inhabiting numerous marine and freshwater reservoirs, both large and small, temporary, both deep and shallow.

Algae inhabit water bodies only at those depths to which it penetrates sunlight... Few types of algae live on stones, tree bark, soil. For living in water, algae have a number of adaptations.

Adaptation to the habitat

For organisms living in oceans, seas, rivers and other bodies of water, water is a habitat. The conditions of this environment differ markedly from terrestrial conditions. Water bodies are characterized by a gradual weakening of illumination as they dive to depth, fluctuations in temperature and salinity, a low oxygen content in water - 30-35 times less than in air. In addition, water movement poses a great danger to seaweed, especially in the coastal (tidal) zone. Here, algae are exposed to such powerful factors as surf and wave impacts, ebbs and flows (Fig. 39).

Algae survival in such harsh conditions aquatic environment possible thanks to special devices.

• With a lack of moisture, the membranes of algae cells thicken significantly and are saturated with inorganic and organic substances. This protects the algae organism from drying out during low tide.
• The body of algae is firmly attached to the ground, therefore, during the surf and impact of waves, they are relatively rarely detached from the ground.
• Deep-sea algae have larger chloroplasts with a high content of chlorophyll and other photosynthetic pigments.
• Some algae have special air-filled bubbles. They, like melts, keep the algae at the surface of the water, where it is possible to capture the maximum amount of light for photosynthesis.
• The release of spores and gametes in algae coincides with the tide. The development of the zygote occurs immediately after its formation, which does not allow the ebb tide to carry it into the ocean.

Algae representatives

Brown algae

Kelp

The seas are inhabited by algae with a yellow-brown color. These are brown algae. Their color is due to the high content of special pigments in the cells.

The body of brown algae has the form of threads or plates. A typical representative of brown algae is kelp (Fig. 38). It has a lamellar body up to 10-15 m long, which is attached to the substrate with the help of rhizoids. Laminaria reproduces asexually and sexually.

Fucus

In shallow water, dense thickets form fucus. Its body is more dissected than that of kelp. In the upper part of the thallus there are special air bubbles, due to which the body of the fucus is kept on the surface of the water.

On this page material on topics:

• algae classification structure and meaning

• which organisms are algae and why

• algae his organs

• what is the transformation of algae in the environment

• what is common in the structure of unicellular and multicellular algae

Questions for this article:

• What organisms are algae?

• It is known that algae inhabit seas, rivers and lakes only at those depths to which sunlight penetrates. How can this be explained?

• What is common and distinctive in the structure of single-cell and multicellular algae?

• What is the main difference between brown algae and other algae?