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Algae - group of organisms of various origins, united by the following characteristics: presence of chlorophyll and photoautotrophic nutrition; in multicellular - lack of clear differentiation body (called thallus or thallus– single-class, multi-class, colonial) to organs ; lack of a pronounced conduction system; living in an aquatic environment or in damp conditions(in soil, damp places, etc.)

Morphological types: 1. Amoeboid structure(named after Pellikulu - compacted peripheral part of the protoplast, serving as a shell) 2. Monad structure(single cell algae with undulipodia and a hard cell wall) 3. Coccoid(no tourniquet, there is a hard wall) 4. Palmelloid(numerous coccoid cells are immersed in the general mucous membrane of the body) 5. filamentous 6. Lamellar(1, 2, many layers of cells) 7. Siphonal(the thallus does not have septa if there is a large number of nuclei) 8. Kharophytnaya(large multi-cell thallus with linear structure)

Aquatic algae: planktonic (phytoplankton -diatoms) and benthic

Reproduction:vegetative(part of the thallus), asexual(zoospores and aplanospores) sexual(chologamy – merging of whole individuals, isogamy, heterogamy, oogamy). Conjugation. Gametophycote and sporophycote. Isomorphic(n=2n externally) and heteromorphic change of generations.

Taxonomy

Superkingdom Eukaryotes, or Nuclear (lat. Eucaryota)

Kingdom of Plants (lat. Plantae)

Subkingdom of Algae (lat. Phycobionta)

Department Green algae (lat. Chlorophyta)

Department Euglenophyta (lat. Euglenophyta)

1 cell, usually 2 bundles, dense or elastic pellicle, 1 nucleus with closed mitosis and condensed chromosomes, plastids are of various shapes and surrounded by a close-fitting layer of eps, chlorophyll a, b + ß-carotene + xanthophylls + others, there is a pyrenoid, food of assimilation paramylon - glucose polymer , the nek has a stigma - an eye made of beta-carotene, sexual reproduction has not been revealed, the pitan is phototrophic, saprotrophic (the nek is holozoic - ingestion of the mouth), mixed,

Department golden algae(lat. Chrysophyta) (often combined with brown) unicl.

Zhelto department green algae(lat. Xanthophyta)

Division Diatoms (lat. Bacillariophyta)

Department Dinophyte algae (lat. Dinophyta = Pyrrophyta)

Single cell, usually with 2 bundles, plankton mainly marine, auto, hetero and mixotrophs, dense cellulum cell wall - theca + pellicle under it, chlorophyll a,c + ɑ,ßcarotenoids + brown pigments (fucoxanthin, peridinin), Vova reserve - starch , fatty oil, propagation: predominantly vegetative and asexual ( various kinds spores), sexual reproduction in females (isogamy)

Department Cryptophyte algae (lat. Cryptophyta)

Department Brown algae(lat. Phaeophyta)

Mainly benthic, sargassum – secondarily plakton. Multicl. Archaic - single or multi-row threads, the remainder is large and dissected by thallus. They have mucous membrane walls with cellulose and algin cells, pectin layer + algin - sodium salt. Matrix im polys fucoidan. Their inclusions are physodes - vesicles with a high content of polyphenols. Usually small disc-shaped plastids without pyrenoids, less often ribbon-shaped and lamellar with a pyrenoid. Xanthophyll (fucoxanthin) + chlorophylls a, c + ß-carotene. The main food supply is the polysaccharide laminarin (deposited in the cytoplasm), alcohol mannitol, fats. 2n predominant Propagation of vegeta (with different parts of the thallus), asexuality (2 strands and immobile spores), sexes (isogamy, heterogamy, oogamy - 2 cords). The zygote germinates without a dormant period. Often the change of generations is iso or heteromorphic. Species: lamilaria, fucus.

Role in biogeocenoses 1. food 2. Soil formation 3. Silicon and calcium cycle 4. Photosynthesis 5 purification (+ waste water) 6. Indicators of purity, salinity 7. Soil formation 8. Fertilizer 9. Agar 10. Algin adhesive, paper, leather, fabrics ( tablets, thread surgeon) 11. Algae are involved in the formation of some types of medicinal mud. 12. Biofuel 13. In research work

Sub-kingdom of Bagryanka(Rhodobionta) . Purple plants are similar to cyanobacteria in their set of pigments (chlorophyll a, d, phycocyanin, phycoerythrin) and this differs from all other plants. Spare substance they have a special purple starch. The cell membrane contains special pectin substances used by humans under the name agaragar in microbiology and the confectionery industry.

The body of the purple thallus (thallus), in the form of multicellular filaments forming pseudoparenchyma plates. They are attached to the substrate by rhizoids. The deepest inhabitants of the seas.

Reproduction is vegetative, sexual and asexual. Feature development cycle absence of flagellar stages, spores and gametes are always motionless, carried by a current of water.

Subkingdom includes one department Rhodophyta, has about 4 thousand species.

Typical representatives of porphyry are nemalion and callitamnion. Let's look at the sexual reproduction of scarlet moths using the example of Nemalion, which lives in the Black Sea. The thallus of this algae consists of thin filaments held together in bundles. The oogonia is bottle-shaped and is called a carpogon. The egg matures in the expanded part of the abdomen. Top part Carpogona is called trichogyne. In numerous antheridia, immobile male sperm gametes mature. They move passively with the flow of water, stick to the trichogyne, protoplasts, sperm and eggs fuse. From the resulting zygote, a carpospore is formed, giving rise to a new plant. Asexual reproduction is carried out by tetraspores.

Marine, attached, chlorophyll a, d + carotenoids + phycobiliproteins (phycoerythrins, phycocyanins + allophycocyanin), prod assim - purplish starch (deposited out of connection with plastids), im pseudoparenchymal thalli (interweaving), im mucous membrane (input into agar and carrageenan), 2-layer wall (pectin - external, hemicells internal) + some deposit calcium carbonate, 1 or many nuclear, plastids numerous in the form of grains or plates. Propagating the vegeta, sexually formed carpospores 2n (oogamy, female sexual organ - carpogon having developed on the carpogonial branch - a composition of the expanded abdomen, and the process of trichogyne, male - antheridia - cute, colorless cells without a strand of spermation) and asexual (ntetraspores). Species: Porphyra

Subkingdom True algae Phycobionta. Contains several departments, of which we are considering 4: diatoms, brown, green and chara algae.

General characteristics: lower phototrophic plants that live mainly in water. The body is represented by a thallus (unicellular, multicellular or colonial) without dividing it into organs and tissues.

Division Diatoms Bacillariophyta. They differ sharply from other groups of algae in the presence of a hard silica shell (shell). Unicellular or colonial species. There is no cellulose shell. The carapace consists of two halves epitheca and hypotheca. Chloroplasts are in the form of grains or plates. Pigments chlorophyll, carotene, xanthophyll, diatomine. Spare product fatty oil. Reproduction is vegetative and sexual. They live everywhere in the seas and fresh water bodies. Representative of Pinnularia.

Odnokl, im frustulu (silica shell), composed of epitheca ( most of operculum) and hypotheca + pellicle, from cat shell and arr. Solitary or colonies, almost all are autotrophs, but there are heterotrophs. Plankton, benthos. There are centric (symmetrical), pennate (billaterally symmetrical), the cat has the ability to actively move, but they do not have a tourniquet. Plastids vary in shape, with or without pyrenoids (in small ones). Chlorophyll a, c + ß,Ɛcarotines + brown xanthophylls (fucoxanthin, diatoxanthin, etc.). food supply - fatty oil, polysaccharides (chrysolamine, valyuzin). Propagating the vegeta (dividing cells into two parts) and sexes (isogamy, oogamy). All diatoms are 2n, ngametes only.

Division Brown algae Phaeophyta. Multicellular inhabitants of the seas, the largest known algae, sometimes up to 60 m long.

The cells have a nucleus, one or several vacuoles, and the membranes are heavily mucused. Chloroplasts are colored brown (pigments: chlorophyll a and c, carotene, xanthophyll, fucoxanthin). Replacement product: laminarin, mannitol and fats. Reproduction is vegetative, sexual and asexual with a clear alternation of generations according to the isomorphic or heteromorphic type.

Representatives: kelp, fucus.

Division Green algae Chlorophyta. The largest department among algae, about 5 thousand species. Its representatives are very diverse in appearance: unicellular, multicellular, siphonal, filamentous and lamellar. They live in fresh or sea water, as well as on soil.

The distinctive feature is the pigment composition, which is almost the same as that of higher plants (chlorophyll a and b, carotenoids). Chloroplasts have a double-membrane membrane, are varied in shape, and may have pyrenoids. The cell membrane consists of cellulose and pectin substances. There are mobile forms with undulipodia. The reserve substance is starch, rarely oil.

Representatives: Chlamydomonas is a unicellular alga, the sexual process is isogamous. Spirogyra is a filamentous algae. The sexual process is conjugation. Caulerpa has a noncellular structure (siphonal), externally resembling stem plants. It is a giant cell with projections sometimes up to 50 cm long, having a single protoplast with a continuous vacuole and numerous nuclei.

Single cell, siphonal, multi cell, filamentous, lamellar. Basically fresh, there is fruit drink and ground water. Chlorophyll a, b, carotenes. whether there are pyrenoids or not. CL single and multi-core. Cellulosnopectin is abundant, rarely only with pellicle. Iso, heteromorphs. The reserve is starch inside the plastids, sometimes oil. Note: Chlamydomanades, Volvox, Chlorella, Spirogyra, Characeae. Propagation is vegetative (division into autospores), sexual (isogamy, less often hetero and oogamy (form oospore), 2, 4, polygonal). Conjugation in filamentous spirogyra.

Types of green algae life cycles: 1.Haplophase – algae develop in a haploid state, only the zygote is diploid (with zygotic reduction). Gapple spores (asexual reproduction). Gametes (n) – fused – zygote (2n) – dormant – germinates after reduction in the number of chromosomes – haploid seedlings. Most algae are 2. Diplophase - the algae is diploid, and the haploid gametiphyte (diatoms, siphonaceae from greens, cyclosporans from brown ones). Thalluses - 2n. Reproduction – sex and vegetative. Before the release of gametes – meiosis – copulation of haploid hapl gametes – zygote 2n. Gametic reduction. 3. Haplodiplophase - algae have a haploid gametophyte, the gametes are united in pairs - a zygote, which germinates into a diploid thallus, on which spores. Sporic reduction. M.b. haplodiplophase life cycle with somatic reduction (less common)

Division of algae Charophyta. Multicellular, divided into parts, externally similar to higher plants. Reproduction is vegetative and sexual (oogamous). Oogonia has characteristic structure, with a shell of 5 spirally twisted cells, forming a crown at the apex. The antheridium is spherical. The zygote, after a period of dormancy, grows into a new plant. Representative – hara brittle.

The meaning of algae. A huge role in the creation of organic substances and oxygen on the planet, in the cycle of substances, as well as in the nutrition of the inhabitants of water bodies. Can carry out self-purification of water. Many algae are indicators of habitat pollution. They can be used as food for humans and farm animals, as well as fertilizers. Used to produce agaragar, sodium alginate (glue). Laminaria, fucus, and spirulina are used in medicine.

TO green algae include both unicellular plants (chlorella, chlamydomonas) and multicellular ones, reaching large sizes(spirogyra, ulotrix, etc.). They are all united common feature- the presence in the cells of a green pigment that is not masked by pigments of other colors. All green algae photosynthesize.

A typical representative of unicellular green algae is chlamydomonas, which is similar in structure to flagellates. It's single celled oval shape algae having two flagella.

An algae cell consists of cytoplasm, a nucleus, a cup-shaped chromatophore with a pyrenoid, a red eye, a pulsating vacuole and a membrane.

Chlamydomonas live in puddles and on damp soil. Reproduce like asexually, zoospores and sexual ones. All three forms of sexual reproduction occur: isogamy, heterogamy, oogamy.

An interesting representative of unicellular green algae is chlorella, species of which live in fresh water, on moist soil, on tree trunks, even in symbiosis (mutually beneficial cohabitation) with animals (ciliates, hydras, worms).

Chlorella means green leaf. It has long attracted the attention of scientists primarily for its extraordinary nutritional properties. Chlorella is interesting because it photosynthesizes very intensively, creating a large number of organic matter, much more than other green plants.

The chlorella yield within 24 hours is up to 200 kg/ha, which is twice the yield of corn. The collected mass of chlorella consists of 50% proteins, 22% fats, 12% carbohydrates, and 10% mineral salts. Chlorella contains vitamins A, B, C. For example, it contains 100 times more vitamin C and 500 times more vitamin A than milk. Chlorella contains twice as much vitamin C as lemon juice. It contains ten amino acids essential for animals.

Finally, in the near future, chlorella in a spacecraft will help create a closed cycle of substances necessary to provide astronauts with food and oxygen on long flights, which is reflected in the diagram.

Chlorella is a plant that performs a cosmic role, which was the dream of the founder of scientific astronautics K. E. Tsiolkovsky. He wrote: “How earth's atmosphere cleansed by plants with the help of the Sun, so it can be renewed and artificial atmosphere spaceship."

Except unicellular algae, there are also colonial forms, a typical representative of which is Volvox, or top. This algae is a spherical colony of cells arranged in one layer. Interior the ball is filled with mucus. The number of cells in a colony is up to 50,000. Very large colony balls reach the size of a pinhead and are visible to the naked eye. Volvox lives in fresh sewage ponds and never-drying puddles.

Of the multicellular algae, the most common filamentous algae in our country are ulothrix and spirogyra. Ulotrix threads reach 10 cm in length. With them, ulotrix attaches to underwater rocks and snags. Ulothrix lives in fresh water bodies.

Asexual reproduction occurs through zoospores. Sexual reproduction occurs according to the type of isogamy.

Green algae

The richest in species-wise The department of algae is green algae, numbering up to 20 thousand species. They are distinguished by the pure green color of their thalli, which is due to the predominance of chlorophyll over all other pigments. Along with chlorophyll, which is identical to the chlorophyll of higher plants, the chloroplast also contains carotenes and xanthophylls. Sometimes the green color of algae can be masked by a red pigment (hematochrome). Spare nutrient the same as in higher plants - starch. Green algae are typical eukaryotes; cells may contain one or more nuclei. The shape of the cell is clearly fixed by dense cellulose and pectin shells.

The morphological structure of representatives of this department is very diverse. Among green algae there are unicellular, colonial, coenobial (unlike a colony in coenobia, the number of cells is always constant) and multicellular species. All types of vegetative body structure inherent in algae in general, except for the amoeboid and tissue structures, can be detected when studying green algae. Green algae vary greatly in size: along with microscopic forms, there are species whose thallus length reaches several tens of centimeters and even a meter.

Green algae have all types of asexual and sexual reproduction. They often reproduce vegetatively.

The department of green algae is a very systematically fragmented group. Still no consensus regarding the position in the department system of various classes. The criteria by which the department is divided into taxonomic ranks have not been established, which is due to the extraordinary diversity of green algae. Most scientists divide the department into classes, depending on the structure of the vegetative body: volvox, chlorococcal (or protococcal), ulothrix, siphon, conjugates.

Volvox algae have a monad structure of the thallus; Most Volvoxidae are solitary species, but some species form coenobia. The cell has a dense cellulose shell, sometimes pectin, one, cup-shaped chloroplast in which pigments are concentrated. A light-sensitive eye - stigma - is associated with the chloroplast; there are one or two pulsating vacuoles. The reserve nutrient is starch. Volvox algae are predominantly autotrophic, but there are known cases of a mixed type of nutrition, and sometimes heterotrophic. These algae usually reproduce vegetatively - by cell division; asexual and sexual reproduction also occurs.

Among Volvox algae, only a small number of species can live in water bodies with high salinity. The bulk of them are inhabitants of stagnant, well-heated reservoirs with fresh water, Their usual habitats are ditches, puddles, and ponds. They feel very good, actively moving through the water column with the help of flagella, in reservoirs treatment facilities, rich in organic matter. Due to the ability for heterotrophic nutrition they play big role in the processes of self-purification of water in wastewater bodies, they are a food source for other inhabitants aquatic environment. With sufficient illumination, appropriate temperature and the presence of nutrients, they develop especially quickly, causing green and red “blooming” of water.

In the reservoirs of the Volvox region, there live such species as Chlamydomonas globulus, Chlamydomonas Reinhardt, Carteria marii, Facotus lenticularis, Gonium pectoralis, Pandorina brambles, Eudorina gracica, Volvox globulus, Volvox golden-yellow.

Volvox algae descended from primary primitive amoeboid ancestors; their evolution followed the path of complication of the sexual process and the structure of the thallus.

Cells of representatives of the class of chlorococcal algae in a vegetative state are completely motionless. These are unicellular or coenobial species. The most primitive representatives of this class inherited the ocellus and flagella from their ancestors, but the latter are motionless and are called pseudocilia. Most species are microscopic and have the most different shapes cells - spherical, spindle-shaped, sickle-shaped. The cell walls are cellulose, sometimes equipped with bristles and spines. They reproduce vegetatively or asexually. The sexual process is known in few species and is rarely observed.

The most famous in the algal flora of the region are Chlorella vulgaris, Scenedesmus four-tailed, Dictyospherium beautiful, Crucigenia quadrate, Pediastrum perforatum and others.

Chlorococcal algae, which trace their ancestry to Volvoxaceae, in turn, in the process of evolution, gave rise to the next class - Ulothrixaceae. In the class of chlorococcal algae, for the first time, the rudiments of new structures appeared in the organization of the vegetative body of algae - filamentous and lamellar.

Most representatives of the ulothrix class have a multicellular filamentous thallus, although lamellar species are also found. The thread consists of one or two layers of cells; it serves as the basis for all more complexly organized thalli. The latter are formed due to cell division in different axes. The lamellar thallus can be single-layered, double-layered, or may have a cavity inside. Ulothrix cells have one nucleus, one chloroplast, occupying a wall position in the form of a plate. Ulothrix can lead either an attached lifestyle or lie freely on the bottom of reservoirs. Reproduction - sexual, asexual, and also vegetative - by pieces of thallus. From the class of Ulothrixaceae, the region contains Pleurococcus vulgaris, Trentepoly tenensis, Ulotrix cingulum, Enteromorpha intestinalis, and Stigeoclonium thin.

Siphon algae have a so-called non-cellular structure. The thallus of these algae is one large cell, sometimes with very complex outlines. This group of algae is quite ancient, and currently its representatives are found mainly in tropical seas. Our flora is characterized by species in which the vegetative body is divided into multinucleate sections, or segments. These are Cladophora weak, Cladophora twisted, Cladophora aegropile, Rhizoclonium hieroglyphic, Spheroplea annulare, Chaetophora graceful, Kützing's microtamnion, Prasiola curly. The chloroplast in such segments has a mesh structure. Sometimes these algae are isolated even in independent class siphonoclady out. They usually reproduce sexually and asexually. IN life cycle There is an alternation of generations - gametophyte and sporophyte.

Conjugates, or conjugates, are predominantly microscopic algae, unicellular or filamentous. Single-celled filaments have bizarre outlines, visible, of course, only under a microscope, and clusters of filaments are visible to the naked eye. The algae of this department received their name from their method of reproduction: conjugation - a temporary connection of two individuals that exchange parts of the nuclear apparatus and cytoplasm. In nature, conjugation occurs at a fairly high water temperature (not lower than 25°C), on a bright sunny day. Two cells or two threads come together, and their contents merge, most often with the help of a bridge connecting either cells of different threads or neighboring cells of the same thread. As a result of the fusion, a zygote is formed, which, after a period of dormancy, gives rise to a new plant. In appearance, conjugate cells are distinguished by their exceptional elegance and delicacy of ornaments covering their shells.

Conjugates can also reproduce vegetatively: in unicellular organisms this is cell division, and in filamentous organisms this is the disintegration of threads into individual cells, from which new threads subsequently grow.

Conjugates are quite numerous in the water bodies of the region. These are Spirogyra, Mujozia, Zygnema, Closterium Kützing, Closterium graceful, Closterium needle-shaped, Closterium lined, Micrasterias truncated, Micrasterias maltese cross, Cosmarium grape-shaped, Cosmarium low, Cosmarium truncated, Staurastrum strange, Staurastrum lunate, Xanthi Dium radiculata.

Bright green, silky-to-touch clusters of Spirogyra are called “mermaid hair.”

Green algae are the largest and most specific group of algae, distinguished by a huge variety of species included here. Their evolution came from primitive flagellar species to multicellular organisms, although the latter did not reach a high level of differentiation. Green algae in the process of development gave rise to charophyte algae - this is one branch of their evolution, the other branch led to the emergence of higher plants.

Today, green algae are considered the most extensive group, which has about 20 thousand species. This includes both unicellular organisms and colonial forms, as well as plants with large multicellular thallus. There are representatives that live in water (sea and fresh), as well as organisms adapted to survive on land in conditions high humidity.

Green algae department: a brief description of

Main hallmark Representatives of this group are characterized by their coloring - all species are characterized by green or green-yellow coloring. This is due to the main pigment of cells - chlorophyll.

As already mentioned, the department brings together completely different representatives. There are unicellular and colonial forms, as well as multicellular organisms with a large, differentiated thallus. Some unicellular representatives move with the help of flagella; multicellular ones, as a rule, are attached to the bottom or live in the water column.

Although there are organisms with naked cells, most representatives have cell wall. Main structural component cell membrane is cellulose, which, by the way, is considered an important systematic characteristic.

The number, size and shape of chloroplasts in a cell may vary depending on the type of plant. The main pigment is chlorophyll, in particular the a and b forms. As for carotenoids, plastids contain mainly beta-carotene and lutein, as well as small amounts of neosanthin, zeaxanthin and violaxanthin. Interestingly, the cells of some organisms have an intense yellow or even orange color - this is due to the accumulation of carotenes outside the chloroplast.

Some unicellular green algae have a specific structure - an eye, which reacts to light in the blue and green spectrum.

The main storage product is starch, the granules of which are contained mainly in plastids. Only some representatives of the order have reserve substances deposited in the cytoplasm.

Department Green algae: methods of reproduction

In fact, representatives of this order are characterized by almost all possible methods of reproduction. can occur through (unicellular representatives without a cell membrane), fragmentation of the thallus (this method is typical for multicellular and colonial forms). In some species, specific nodules are formed.

Asexual reproduction is represented by the following forms:

• zoospores - cells with flagella, capable of active movement;
• aplanospores - such spores do not have a flagellar apparatus, but well-developed cells are not capable of active movement;
• autospores - this type of spores is primarily associated with adaptation to the external environment. In this form, the body can wait out dry conditions and other unfavorable conditions.

Sexual reproduction can also be diverse - this includes oogamy, heterogamy, hologamy, as well as isogamy and conjugation.

Order Green algae: characteristics of some representatives

Many people belong to this group famous representatives flora. For example, spirogyra and chlorella are also included in the order.

Chlamydomonas - enough famous family green algae, which is of great practical importance. This group includes single-celled organisms with a red eye and a large chromatophore that contains pigments. It is Chlamydomonas that causes the “blooming” of ponds, puddles and aquariums. In the presence sunlight organic matter produced by photosynthesis. But this organism can absorb substances from external environment. Therefore, chlamydomonas is often used to purify water.

Algae, unicellular and multicellular forms of benthic algae. All morphological types of thallus are found here, except for rhizopodial unicellular and large multicellular forms with complex structure. Many filamentous green algae are attached to the substrate only by early stages development, then they become free-living, forming mats or balls.

Green algae
Diversity of siphon algae. Illustration from Ernst Haeckel's book Kunstformen der Natur, 1904
Scientific classification
International scientific name
Chlorophyta Pascher, 1914
Taxonomy on Wikispecies Images on Wikimedia Commons ITIS NCBI EOL

Green algae is the most extensive given time department of algae: according to rough estimates, this includes from 13,000 to 20,000 species. All of them are distinguished primarily by the pure green color of their thalli, similar to the color of higher plants and caused by the predominance of chlorophyll over other pigments.

Structure

The flagellar cells of green algae are isokont - the flagella have a similar structure, although they can vary in length. There are usually two flagella, but there can also be four or many. Flagella of green algae do not have mastigonemes (unlike heterokonts), but may have graceful hairs or scales.

Life cycles

The life cycles of green algae are very diverse. There are all kinds of types here.

Haplobiont with zygotic reduction ( Hydrodictyon reticulatum, Eudorina). Biflagellate gametes are released from the parent cell through a pore in its membrane; the fusion of gametes is carried out using a tube. Next, the zygote turns into a resting zygospore, and after a period of physiological dormancy it germinates to form 4 zoospores (as a result of meiotic division). Each zoospore forms a polyhedron and germinates, forming small spherical networks of adherent zoospores.

Haplo-diplobiont with sporic reduction ( Ulva, Ulothrix, some types Cladophora). Biflagellate isogametes emerge from the mother cell, after which the gametes formed by different filaments merge in water. A four-flagellate zygote is formed, which actively floats in the water. After this, it descends onto some substrate and becomes covered with a dense shell, thus turning into a club-shaped cell (codiolum), followed by a stage of physiological rest. When advancing favorable conditions germinates into 4-16 zoospores or aplanospores, which, after a short period of swimming, attach to the substrate and grow into new filaments. Activate exit from dormant state various factors: temperature increase, environmental change, etc.

Diplobiont with gametic reduction ( Bryopsis). The planozygote settles and grows into a filamentous thallus with a large nucleus; the nucleus divides, thus forming stephanokont zoospores that grow into the vegetative thallus.

Especially a lot of green algae develops in the spring, when all the stones in the littoral zone are covered with a continuous emerald coating of green algae, sharply contrasting with the white snow lying on the coastal stones. A fleecy green carpet on the stones is formed by developing filaments - ulotrix ( Ulothrix) and urospora ( Urospora). In summer, a lot of Egagropyla often develops ( Aegagropila linnaei) (syn. Cladophora aegagropila), which often looks like a green mucous mass. On the open rocky coast, bright green branched bushes form acrosiphony ( Acrosiphonia).

Role in nature and use

Some green algae (such as ulva) are widely eaten. Chlorella is used as an indicator of water pollution levels and is found on spacecraft. submarines for purifying air from carbon dioxide.