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Algae are a group of organisms of various origins, united by the following characteristics: the presence of chlorophyll and photoautotrophic nutrition; in multicellular - lack of clear differentiation body (called thallus, or thallus- single, multiple, colonial) on organs ; lack of a pronounced conductive system; living in an aquatic environment or in humid conditions(in soil, damp places, etc.)
Morphological types: 1... Amoeboid structure(named after Pelliculu - the compacted peripheral part of the protoplast, serving as a shell) 2. Monad structure(odnokl Wodorsli with undulipodia and a hard cell wall) 3. Coccoid(no tourniquet, there is a solid wall) 4. Palmeloid(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 is not cl with partitions in the presence of a large number of nuclei) 8. Harophytic(large multicellular thallus with linear segmented structure)
Aquatic algae: planktonic (phytoplankton - diatoms ) and benthic
Reproduction:vegetative(part of the thallus), asexual(zoospores and aplanospores) sexual(hologamy - plums of whole individuals, isogamy, heterogamy, oogamy). Conjugation. Gametophycot and sporophyte. Isomorphic(n = 2n outwardly) and heteromorphic change of generations.
Taxonomy
Super Kingdom of Eukaryotes, or Nuclear (lat.Eucaryota)
Kingdom of Plants (lat.Plantae)
Subkingdom of Algae (Latin Phycobionta)
Department Green algae (lat.Clorophyta)
Department of Euglena algae (lat.Euglenophyta)
1cl, more often 2 bundle, dense or elastic pellicle, 1 nucleus with closed mitosis and condensed chromasomes, plastids have a different shape and surrounded by a dense layer of eps, chlorophyll a, b + ß-carotene + xanthophylls + others, there is a pyrenoid, glucose assimilation paramilon - polymer , a certain person has a stigma - a peephole from ß-carotene, sexual reproduction has not been detected, phototrophic, saprotrophic (in a non-holozoic - swallowing mouths), mixed,
Division Golden algae (lat. Chrysophyta) (often combined with brown algae) onecl.
Department of Yellow-green algae (lat.Xanthophyta)
Department of Diatoms (lat.Bacillariophyta)
Department Dinophyta algae (Latin Dinophyta = Pyrrophyta)
One, more often with 2 bundles, plankton mostly marine, auto, hetero and mixotrophs, dense cell wall - theca + pellicle under it, chlorophyll a, c + ɑ, ß-carotenoids + brown pigments (fucoxanthin, peridinin), vova stock - starch , fatty oil, reproduction: predominantly vegetative and asexual (various kinds of spores), sexual reproduction at a neck (isogamy)
Department of Cryptophyta algae (lat.Cryptophyta)
Department of Brown algae (lat.Phaeophyta)
Mostly benthic, sargassum - secondarily plankton. Many cl. Archaic - one or many strands, the rest is large and dissected by thallus. They have a mucous membrane from the wall with cellulose and alginic cells, pectin layer + algin - sodium salt. The matrix is named after the policy of fucoidan. They include - physodes - bubbles with a high content of polyphenols. Usually small discoid plastids without pyrenoids, less often ribbon-like and lamellar with pyrenoid. Xanthophyll (fucoxanthin) + chlorophylls a, c + ß-carotene. The main supply of food is the polysaccharide laminarin (deposition in the cytoplasm), mannitol alcohol, fats. 2n predominance. Propagation of vegetation (with the help of parts of the thallus), asexual (2 burn and immobile spores), sexes (isogamy, heterogamy, oogamy - 2 burn). The zygote germinates without a dormant period. Often the generational change is iso or heteromorphic. Species: lamilaria, fucus.
Role in biogeocenoses 1. food 2. Soil sample 3. Silicon and calcium cycle 4. Photosynthesis 5 purification (+ waste water) 6. Indicators of purity, salinity 7. Soil 8. Fertilizer 9. Agar 10. Algin gluing, paper leather, fabric ( pills, thread surgeon) 11. Algae are involved in the formation of certain types of therapeutic mud. 12. Biofuel 13. In research work
The sub-kingdom of the Crimson Woman(Rhodobionta) . Bagryanka are similar to cyanobacteria in a set of pigments (chlorophyll a, d, phycocyanin, phycoerythrin) and differ in this from all other plants. They have a special crimson starch as a reserve substance. The cell membrane contains special pectin substances used by humans called agaragar in microbiology and the confectionery industry.
The body of the purplish thallus (thallus), in the form of multicellular filaments, forming pseudoparenchymal plates. They are attached to the substrate by rhizoids. The deepest inhabitants of the seas.
Reproduction is vegetative, sexual and asexual. A characteristic feature of the developmental cycle is the absence of flagellar stages, spores and gametes are always motionless, carried by the current of water.
The subkingdom includes one Rhodophyta department, has about 4 thousand species.
Typical representatives are porphyry, nemalion, callitamnion. Consider sexual reproduction purple on the example of Nemalion living in the Black Sea. The thallus of this algae consists of thin threads held together in bundles. Oogonium is bottle-shaped and is called carpogon. The ovum matures in the enlarged part of the abdomen. Top part carpogonum is called trichogina. In numerous antheridia, immobile male gametes of sperm mature. With the flow of water, they passively move, adhere to the trichogyne, the protoplasts, sperm and eggs merge. 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 - purple starch (deposited outside the connection with plastids), they are pseudoparenchymal thalli (interlacing with nia), they are mucous membrane carrageenan), cell wall 2-layer (pectin - outside, hemicelle inside) + some deposit of calcium carbonate, 1 or many nuclei, plastids are numerous in the form of grains or plates. Propagation of vegetation, sexes of arr carpospore 2n (oogamy, female sex organ - carpogon developing on the carpogonial branch - composition of the abdominal expansion and trichogina process, husband - antheridia - cute colorless cells without sperm cord) and asexual (ntetraspores). Species: porphyra (Porphyra)
Subkingdom Real Phycobionta algae. It contains several sections, of which we are considering 4: diatoms, brown, green and charovy 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.
Department of Diatoms Bacillariophyta. They sharply differ from other groups of algae by the presence of a hard silica shell (shell). Single-celled or colonial species. There is no cellulose casing. The carapace consists of two halves of the epithecus and the hypotheca. Chloroplasts 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. Pinnularia representative.
Odnokl, im frustula (silica shell), composition from epithecus ( most of lid) and hypotheca + pellicle, from cat shell and arr. Solitary or colonies, almost all autotrophs, but there are heterotrophs. Plankton, benthos. There are centric (symmetric), pennate (bilaterally symmetric), the cat is able to move actively, but they do not have a tourniquet. Plastids are split in shape, with or without pyrenoids (in small ones). Chlorophyll a, c + ß, Ɛcaratins + brown xanthophylls (fucoxanthin, diatoxanthin, etc.). food stock - fatty oil, polysaccharides (chrysolaminarin, valatin). Propagation of vegetation (cases of cl on valves in two), sexes (isogamy, oogamy). All diatoms are 2n, n gametes only.
Division Brown algae Phaeophyta. Multicellular sea dwellers, the largest known algae, sometimes up to 60 m long.
The cells have a nucleus, one or more vacuoles, and the membranes become very mucous. Chloroplasts are brown colored (pigments: chlorophyll a and c, carotene, xanthophyll, fucoxanthin). Spare 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.
Department Green algae Chlorophyta... The largest department among algae, about 5 thousand species. Its representatives are very diverse in outward appearance: unicellular, multicellular, siphonal, filamentous and lamellar. They live in fresh or sea water, as well as on soil.
A distinctive feature of the pigment composition is almost the same as that of higher plants(chlorophyll a and b, carotenoids). Chloroplasts have a two-membrane shell, vary in shape, and may be pyrenoids. The cell wall 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 is a non-cellular structure (siphonal), outwardly reminiscent of stem plants. It is a giant cell with outgrowths sometimes up to 50 cm long, having a single protoplast with a continuous vacuole and numerous nuclei.
Single, siphonal, multicl, filamentous, lamellar. Basically fresh, there is fruit drink and ground. Chlorophyll a, b, carotenes. pyrenoids are there or not. CL single and multi-core. Cellulose-pectin obol., Rarely only with a pellicle. Iso, heteromorphs. Stock - starch inside plastids, sometimes oil. Example: Chlamydomanades, Volvox, Chlorella, Spirogyra, Charovye. Reproduction of vegetation (division into autospores), sexual (isogamy, less often hetero and oogamy (arr oospore), 2, 4, many burns). Conjugation in filamentous spirogyra.
Life Cycle Types of Green Algae: 1.Haplophase - algae develop in a haploid state, only a diploid zygote (with a zygotic reduction). Hapl spores (asexual reproduction). Gametes (n) - sliane - zygote (2n) - dormancy - germinates after reduction of the number of chromosomes - haploid seedlings. Most of the algae 2. Diplophase - the alga is diploid, and the haploid gametyphyte (diatoms, siphon algae from greens, cyclosporous algae from brown ones). Thallus - 2n. Reproduction - sex and vegetation. Before the gamete obesity - meiosis - copulation of gamete haploid haples - 2n zygote. Gametic reduction. 3. Haplodiplophase - algae has a haploid gametophyte, gametes are combined in pairs - a zygote, which grows with a diploid thallus, on which there are spores. Spore reduction. M. b. haplodiplophasic life cycle with somatic reduction (less often)
Department of Charoe algae Charophyta... Multicellular, dissected into parts, outwardly similar to higher plants. Reproduction is vegetative and sexual (oogamous). Oogonium has a characteristic structure, with a shell of 5 spirally twisted cells, forming a crown at the apex. The antheridium is spherical. After a dormant period, the zygote germinates into a new plant. The representative is hara brittle.
The value of algae... A huge role in the creation of organic matter and oxygen on the planet, in the circulation of substances, as well as in the nutrition of the inhabitants of reservoirs. They can carry out self-purification of waters. Many algae are indicators of habitat pollution. Can be used as food for humans and farm animals, as well as fertilizers. Used to obtain agaragar, sodium alginate (glue). In medicine, kelp, fucus, spirulina are used.
ALGAE: CLASSIFICATION OF ALGAE
To the article ALGAE
In the past, algae were considered primitive plants (without specialized conductive or vascular tissues); they were allocated to the subdivision of algae (Algae), which, together with the subdivision of fungi (Fungi), constituted the department of thallus (layered), or lower plants (Thallophyta), one of the four departments of the plant kingdom (some authors use the zoological term instead of the term "department" a type"). Further, the algae were divided by color - into green, red, brown, etc. Color is a strong enough, but not the only basis for general classification these organisms. The types of formation of their colonies, methods of reproduction, peculiarities of chloroplasts, cell walls, storage substances, etc. are more important for the isolation of various groups of algae. The old systems usually recognized about ten such groups, which were considered classes. One of the modern systems refers to "algae" (this term has lost its classification meaning) eight types (divisions) of the kingdom of protists (Protista); however, this approach is not recognized by all scientists.
Green algae make up the Chlorophyta division (type) of the protist kingdom. They are usually grass green (although they can range from pale yellow to nearly black in color) and have the same photosynthetic pigments as normal plants. Most are microscopic freshwater forms. Many species grow on soil, forming felt-like deposits on its wet surface. They are unicellular and multicellular, form filaments, spherical colonies, leaf-like structures, etc. Cells are mobile (with two flagella) or immobile. Sexual reproduction - different levels of difficulty depending on the species. Several thousand species have been described. The cells contain a nucleus and several well-defined chloroplasts. One of the well-known genera is Pleurococcus, a unicellular alga that forms green plaques often seen on the bark of trees. The genus Spirogyra is widespread - filamentous algae that form long filaments of mud in streams and cold rivers. In the spring, they float as sticky yellowish-green clusters on the surface of ponds. Cladophora grows as soft, highly branching "bushes" that attach to rocks near river banks. Basiocladia forms a green coating on the back of freshwater turtles. The water mesh (Hydrodictyon), which is composed of many cells, which lives in stagnant waters, in structure really resembles a "string bag". Desmidia - unicellular green algae that prefer soft swamp water; their cells are distinguished by a bizarre shape and a beautifully ornamented surface. In some species, cells are connected in filamentous colonies. In the free-swimming colonial alga Scenedesmus, sickle-shaped or oblong cells are united in short chains. This genus is common in aquariums, where its mass reproduction results in a green "fog" in the water. The largest green algae- sea lettuce (Ulva), leaf-shaped macrophyte.
Red algae (crimson algae) make up the Rhodophyta division (type) of the protist kingdom. Most of them are marine leafy, bushy or crustal macrophytes that inhabit below the low tide line. Their color is predominantly red due to the presence of the phycoerythrin pigment, but can be purple or bluish. Some scarlet species are found in fresh water, mainly in streams and clear fast rivers. Batrachospermum is a highly branched algae, gelatinous to the touch, consisting of brownish or reddish bead-like cells. Lemanea is a brush-like form, often growing in fast-flowing rivers and waterfalls, where its thalli attach to rocks. Audouinella is a filamentous algae found in small rivers. Irish moss (Chondrus cripus) is a common marine macrophyte. The scarlet cells do not form motile cells. Their sexual process is very complex, and one life cycle includes several phases.
Brown algae make up the Phaeophyta division (type) of the protist kingdom. Almost all of them are sea dwellers. Only a few species are microscopic, and the largest algae in the world are found among macrophytes. TO the last group include kelp, macrocystis, fucus, sargassum and lessonia ("sea palms"), the most abundant along the coasts of cold seas. All brown algae are multicellular. Their color varies from greenish-yellow to dark brown and is due to the pigment fucoxanthin. Sexual reproduction is associated with the formation of mobile gametes with two lateral flagella. Instances that form gametes are often completely different from organisms of the same species, which reproduce only by spores.
Diatoms (diatoms) are grouped into the class Bacillariophyceae, which in the classification used here, together with golden and yellow-green algae, belong to the Chrysophyta division (type) of the protist kingdom. Diatoms are a very large group of unicellular marine and freshwater species. Their color is from yellow to brown due to the presence of the pigment fucoxanthin. The protoplast of diatoms is protected by a box-shaped silica (glass) shell - a shell consisting of two valves. The hard surface of the valves is often covered with a complex pattern of striae, tubercles, pits, and ridges characteristic of the species. These shells are some of the most beautiful microscopic objects, and the clarity of their pattern is sometimes used to check the resolving power of the microscope. Usually, the valves are pierced with pores or have a gap called a seam. The cell contains the nucleus. In addition to cell division in two, sexual reproduction is also known. Many diatoms are free-floating forms, but some are attached to underwater objects with slimy legs. Sometimes cells join together in strands, chains, or colonies. There are two types of diatoms: cirrus with elongated bilaterally symmetric cells (they are most abundant in fresh waters) and centric, the cells of which, when viewed from the valve, look round or polygonal (most of them are in the seas).
As already mentioned, the shells of these algae persist after cell death and settle to the bottom of water bodies. Over time, their powerful accumulations are compacted into a porous rock - diatomite.
Flagellate. These organisms, due to their ability for "animal" nutrition and a number of other important features, are now often referred to the subkingdom of the simplest (Protozoa) of the protist kingdom, but they can also be considered as a division (type) of Euglenophyta that is not part of the Protozoa of the same kingdom. All flagellates are unicellular and mobile. Cells are green, red, or colorless. Some species are capable of photosynthesis, while others (saprophytes) absorb dissolved organic matter or even ingest solid particles. Sexual reproduction is known only in a few species. A common inhabitant of ponds is Euglena, a green algae with a red "eye". She swims with the help of a single flagellum, capable of both photosynthesis and feeding on ready-made organic matter. In late summer, Euglena sanguinea can color the pond water red.
Dinoflagellates. These unicellular flagellate organisms are also often ranked among the simplest, but they can also be distinguished into an independent division (type) of Pyrrophyta of the protist kingdom. They are mostly yellow-brown, but sometimes colorless. Their cells are usually mobile; the cell wall is absent in some species, and sometimes it is of a very bizarre shape. Sexual reproduction is known in only a few species. The marine genus Gonyaulax is one of the reasons for the "red tides": off the coast, it is so abundant that the water takes on an unusual color. This algae releases toxic substances that sometimes kill fish and shellfish. Some dinoflagellates cause phosphorescence in tropical seas.
Golden algae, along with others, are included in the Chrysophyta division (type) of the protist kingdom. Their color is yellow-brown, and the cells are mobile (flagellate) or immobile. Asexual reproduction with the formation of silica-impregnated cysts.
It is now customary to combine yellow-green algae with golden algae into the Chrysophyta division (type), but they can also be considered an independent Xanthophyta division (type) of the protist kingdom. They are similar in shape to green algae, but differ in the predominance of specific yellow pigments. Their cell walls sometimes consist of two halves entering one another, and in filamentous species these valves are H-shaped in longitudinal section. Sexual reproduction is known in only a few forms.
Charovye (rays) are multicellular algae that make up the Charophyta division (type) of the protist kingdom. Their color varies from grayish-green to gray. The cell walls are often encrusted with calcium carbonate, so the dead remains of charovy are involved in the formation of marl deposits. These algae have a cylindrical, stem-like main axis, from which lateral processes, similar to plant leaves, extend in whorls. Charovaceae grow vertically in shallow water, reaching a height of 2.5-10 cm. Sexual reproduction. Chars are unlikely to be close to any of the groups listed above, although some botanists believe that they are descended from green algae. See also PLANT SYSTEMATICS.
Collier. Collier's Dictionary. 2012
See also the interpretations, synonyms, meanings of the word and what is ALGAE: CLASSIFICATION OF ALGAE in Russian in dictionaries, encyclopedias and reference books:
- SEAWEED in Encyclopedia Biology:
, a vast group of photosynthetic organisms, sometimes isolated into a particular plant kingdom. Includes 12 sections (blue-green algae, brown algae, green algae, ... - SEAWEED
(Algae) - lower plant organisms, reckoned to the sub-kingdom of spore, or secret marriage, plants (Sporophyta s. Kryptogamae). Together with mushrooms and lichens ... - SEAWEED
(Algae)? lower plant organisms, reckoned with the sub-kingdom of spore, or cryptogamous, plants (Sporophyta s. Kryptogamae). Together with mushrooms and lichens ... - SEAWEED in Collier's Dictionary:
(Algae), a vast and heterogeneous group of primitive, plant-like organisms. With few exceptions, they contain the green pigment chlorophyll, which is essential for ... - CLASSIFICATION in the Newest Philosophical Dictionary:
(Latin classis - category, class and f acio - do, lay out) - multi-stage division of the logical scope of a concept (logic) or some ... - CLASSIFICATION
GOODS - assignment by customs authorities Russian Federation specific goods to the items specified in the Commodity Nomenclature of Foreign Economic Activity (TN VED). ... - CLASSIFICATION in the Dictionary of Economic Terms:
FIXED ASSETS - a grouping of fixed assets established by the USSR State Statistics Committee and including 12 types: buildings; structures; transmission devices; cars and equipment; transport ... - CLASSIFICATION in the Dictionary of Economic Terms:
BUDGET - see BUDGET CLASSIFICATION ... - CLASSIFICATION in the Dictionary of Economic Terms:
- the distribution, separation of objects, concepts, names by classes, groups, categories, in which objects that have c.-l. fall into one group. general ... - CLASSIFICATION in Encyclopedia Biology:
in biology, the distribution of the diversity of living organisms in a certain order in accordance with the system. The classification is based on a set of features that make it possible ... - SEAWEED v Bible Encyclopedia Nikifor:
or SEA GRASS (Ion 2: 6) sea, water grass, as read in the Russian translation in the quoted quotation. The sea grass was ... - SEAWEED in Medical terms:
(algae) a group of autotrophic chlorophyll-bearing, usually aquatic lower plants, not dissected into roots, stems and leaves, capable of assimilating carbon dioxide v … - CLASSIFICATION
(from Latin classis - class and ... fication), in logic - a system of subordinate concepts (classes of objects) of any area of knowledge or ... - SEAWEED in the Big Encyclopedic Dictionary:
a group of lower aquatic plants, usually containing chlorophyll and producing organic matter in the process of photosynthesis. The body of the algae is a thallus that does not have ... - SEAWEED in the Great Soviet Encyclopedia, TSB:
(Algae), a group of lower, autotrophic, usually aquatic, plants; contain chlorophyll and other pigments and produce organic matter during photosynthesis. ... - CLASSIFICATION v Encyclopedic dictionary Brockhaus and Euphron:
a very important logical technique that is used in the study of the subject and which is based on the logical division of concepts. Indeed, the classification is not ... - CLASSIFICATION in the Modern Encyclopedic Dictionary:
- CLASSIFICATION
(from the Latin classis - category, class and ... fication) (in logic), a system of subordinate concepts (classes of objects) of any field of knowledge or activity ... - CLASSIFICATION in the Encyclopedic Dictionary:
and, well. 1. pl. no. Distribution of certain objects into classes depending on their properties. || Cf. RUBRICATION. 2. ... - CLASSIFICATION in the Encyclopedic Dictionary:
, -and, w. 1. see classify. 2. The system for a cut of something. . classified. K. Sciences. Library room II app. classification, th, ... - CLASSIFICATION
CLASSIFICATION OF LANGUAGES, study and grouping of languages of the world by decomp. signs: genetic. K.ya. (genealogical) - on the basis of kinship, i.e. common origin ... - CLASSIFICATION in the Big Russian Encyclopedic Dictionary:
CLASSIFICATION OF SCIENCES, disclosure of the mutual connection of sciences based on the definition. principles (objective, subjective, coordination, subordination, etc.) and the expression of their connection ... - CLASSIFICATION in the Big Russian Encyclopedic Dictionary:
CLASSIFICATION (min.), Separation of particles of crushed minerals into uniform in size, density and other products (classes). K. is produced in ... - CLASSIFICATION in the Big Russian Encyclopedic Dictionary:
CLASSIFICATION (from Latin classis - category, class and ... fication) (in logic), a system of subordinate concepts (classes of objects) k.-l. area ... - SEAWEED in the Big Russian Encyclopedic Dictionary:
ALREADS, group predominantly. water organisms, usually containing chlorophyll and producing organic. in-islands in the process of photosynthesis. V.'s body is a thallus that does not have ... - CLASSIFICATION in the Brockhaus and Efron Encyclopedia:
? a very important logical technique that is used in the study of the subject and which is based on the logical division of concepts. Indeed, there is a classification ... - CLASSIFICATION
classification, classification, classification, classification, classification, classification, classification, classification, classification, classification, classification, classification, classification, ... - SEAWEED in the Complete Accentuated Paradigm by Zaliznyak:
in "matured, in" matured, in "matured, in" matured, in "matured, ... - CLASSIFICATION in the Dictionary of Linguistic Terms:
(from Latin classis - category + facere - to put) vowels, see vowel sounds ... - CLASSIFICATION in the Popular Explanatory and Encyclopedic Dictionary of the Russian Language:
-and, w. 1) The system of subordinate concepts (classes of objects) in some. branch of knowledge, compiled on the basis of taking into account the properties of objects and natural ... - CLASSIFICATION in the Thesaurus of Russian Business Vocabulary:
- CLASSIFICATION in the New Dictionary of Foreign Words:
(lat.; see classify) 1) a system of subordinate concepts (classes of objects, phenomena) in some. branch of knowledge, compiled on the basis of ... - CLASSIFICATION in the Dictionary of Foreign Expressions:
[lat .; see classify] 1. a system of subordinate concepts (classes of objects, phenomena) in some. branch of knowledge, compiled on the basis of taking into account general ... - CLASSIFICATION in the Thesaurus of the Russian language:
Syn: classifying, organizing, organizing, organizing, grouping, sorting, placing, ... - CLASSIFICATION in Abramov's Dictionary of Synonyms:
cm. … - CLASSIFICATION in the dictionary of Synonyms of the Russian language:
Syn: classifying, organizing, organizing, organizing, grouping, sorting, placing, ... - CLASSIFICATION in the New Explanatory Dictionary of the Russian Language by Efremova:
f. 1) The same as: classification. 2) Distribution system homogeneous objects or concepts by classes, categories, etc. according to …
GENERAL CHARACTERISTICS OF ALGAE
The difference between algae and other plants. Algae nutritional methods. Pigments of the photosynthetic apparatus. Phototrophic, heterotrophic and mixotrophic methods of algae nutrition. Cell structure. The main types of morphological structure of the body of algae. Reproduction and development cycles of algae (vegetative, asexual, sexual reproduction). Change of generations and nuclear phases in the life cycles of algae.
Algae and environment. External living conditions. Ecological groups of algae. Planktonic algae. Benthic algae. Terrestrial algae. Soil algae. Snow and ice algae. Salt water algae. Glowing algae. Cohabitation of algae with other organisms.
The value of algae in nature and human life.
Algae classification.
SYSTEMATIC OVERVIEW OF ALGAE
Department of blue-green algae (Cyanophyta). Organization levels. Cell structure. Thallus structure. Reproduction. Classification. Classes are chroococcal, hormogonium, chamesiphon. Origin, evolution and phylogeny. Environmental features. Distribution and representatives. Meaning.
Department of green algae (Chlorophyta). Organization levels. Cell structure. Types of morphological organization of thalli. Reproduction methods. Significance in nature and human life. Division classification. Principles of classification. Classes are equal-pectoral, prasinophytic, conjugates, chara.
The class is ravine, or actually green algae. The orders are volvox, chlorococcal, ulotrix. Unicellular, colonial and coenobial forms. The structure of multicellular thalli. Reproduction. Cell structure. Key representatives.
Conjugate class. Features of the organization and structure of thalli. Reproduction methods. Characteristics and types of conjugation. The orders are mesothenic, desmidian, zignemic. Distribution in nature. Representatives.
Charovye class. Thallus structure. Reproduction methods. Ecology and significance. Key representatives.
Time of occurrence of green algae. Origin, evolution and phylogeny. The main lines of evolution within orders. Green algae as ancestors of higher plants.
Department of diatoms (Diatomeae, Bacillariophyta). Features of the organization and structure of colonies . Cytological features. Reproduction methods. Classification. The classes are pennate and centric. Key representatives. Distribution, ecology, meaning. Representatives. Time of occurrence, origin and phylogeny of diatoms.
Department of brown algae (Phaeophyta). Organization level. Anatomical and morphological structure of thalli. Cytological features. Reproduction methods. Life cycle types. Division classification. The classes are isogenetic, heterogeneous, cyclosporous. Key representatives. Spreading. Ecology. Meaning. Time of occurrence, origin and phylogeny of diatoms.
Classification and structure of algae
The algae world is huge. He occupies a very special place in the plant kingdom, exceptional in its significance, both in the historical aspect and in the role that belongs to him in the general circulation of substances in nature. At the same time, the very concept of "algae" in the scientific sense suffers from great uncertainty. This forces us to deliberately discern the difference between the plant organisms referred to here from the rest of the plant kingdom. Indeed, the word "algae" means only that these are plants living in water. But in botany, this term is used in a narrower sense, and not all plants that we observe in water bodies can be called algae. On the other hand, we often simply do not notice algae specifically in water bodies, since very many of them are not easy to recognize. naked eye... Looking closely at different bodies of water, especially lakes, we first notice the richness of plants. Some of them are attached to the bottom. These include, for example, large green clusters of so-called ooze. Larger algae are often found here, consisting of ordinary or branching threads that are perfectly visible to the eye, or completely large choral algae, which look like horsetail from the outside. On the other hand, a significant amount of microscopic algae, the same as in water bodies, grows on land: on the surface of the earth and in its very thickness, on trees, stones. True, the life of these algae is also closely related to water, but they can only enjoy atmospheric and ground moisture, dew. Unlike "water" algae, these algae simply endure drying and very soon come to life with the slightest moisture. In the plant kingdom, algae belong to the vast subkingdom of lower or layered plants, which also includes bacteria, fungi and lichens. Like all lower plants, algae reproduce vegetatively or with the help of spores, that is, they belong to spore plants. But in physiological terms, algae differ sharply from other lower plants by the presence of chlorophyll, thanks to which they are able to assimilate carbon dioxide in the light. In addition, many algae possessing a well-developed chlorophyll, in addition to phototrophic, can be characteristic of other types of nutrition. thus, based on what has been said, it is easy to derive a clear scientific definition of algae. Algae are lower, that is, layered spore plants containing chlorophyll in their own cells, and living in to a greater extent in water. Such a definition, but does not give an idea of how great variety in the structure of the body, which is characteristic of algae. Here we meet with microscopic organisms - unicellular and multicellular, and with large forms of various structures. Methods of reproduction and the structure of reproductive organs achieve a great contrast here. Even in color, algae are not the same, since some contain only chlorophyll, the rest still have a number of additional pigments that color them in different colors. The division of algae into systematic groups of the highest rank basically coincides with the nature of their color, naturally associated with structural features. Algae are divided into 10 sections:
Blue-green algae;
Pyrophytic algae;
Golden algae;
Diatoms;
Yellow-green algae;
Brown algae;
Red algae;
Evshenovy algae;
Green algae;
Choral algae.
Blue-green algae differ sharply from other algae by the simplicity of the internal organization of cells. Their cells are devoid of a formed nucleus, which brings them closer to bacteria. Together with bacteria, blue - green algae make up a section of organisms designated as prokaryotes, that is, "prenuclear", in contrast to all other plants and animals that own a formed cell nucleus and are designated as eukaryotes.
A cell is the basic structural unit of the body of algae, represented by either unicellular or multicellular forms.
The zest of unicellular forms is determined by the fact that organisms here consist of only one cell, therefore, cellular and organismal features are mixed in its structure and physiology.
A small unicellular alga that is not visible to the ordinary eye plays the role of a specific factory that extracts raw materials, processes them and produces such valuable compounds as proteins, carbohydrates and fats. In addition, oxygen is considered the principal product of its activity. Thus, she actively participates in the cycle of substances in nature. From time to time, unicellular algae form temporary or permanent clusters in the form of colonies.
Multicellular forms appeared after the cell made a long and difficult path development as an independent organism.
When you get acquainted with algae, an extraordinary abundance of both forms and sizes of their cells catches your eye. A large variety of pictures is found in free-living unicellular algae.
In algae, in contrast to higher plants, cells are found, the contents of which are surrounded only by a narrow membrane. Such cells are traditionally called naked. They are unable to maintain their shape and are constantly in the amoeboid state. Cells of this kind are found both among unicellular and multicellular algae, most often at the stage of gametes and zoospores.
The cells of some algae (euglena, yellow-green), in addition to the plasmalemma, are surrounded by a leathery, elastic layer. This layer is called the pellicle, or periplast. It is composed of a fibrillar substance and has a complex, multi-layered company. Cells with such a pellicle are traditionally quite variable in shape. Only a thick, shell-like pellicle can firmly fix it. From time to time, folds appear on the surface of the pellicle, outgrowths in the form of teeth or thickenings, called scales. These structures, in various combinations, form the most unusual patterns, giving the body a unique look. But their main function is to increase the strength of the cell cover.
The cell walls of algae are very diverse both in their structure and in chemical composition. The thickness of the shell varies not only from species to species, but even within the same species, depending on the age of the cell.
Primary and secondary membranes are distinguished by the time of inception and the characteristics of growth. In actively dividing cells, only the primary membrane traditionally appears. Its growth goes in two directions: the surface increases and the thickness increases.
The secondary membrane undergoes hydration, becomes elastic and gets the ability to stretch.
The shells of many algae are supplied with various kinds of outgrowths in the form of bristles, spines and scales. Their role for the cell is ambiguous: in some cases they perform a protective function, while in others they provide rational living conditions.
Green algae - unicellular, colonial and multicellular forms, of various structures, Green colour... Assimilation product - starch, flour, oil. There are both mobile forms with flagella at the anterior end of the cells, and immobile, attached or passively floating. Reproduction is vegetative, asexual and sexual. A number of forms have an alternation of asexual and sexual reproduction. Zoospores and gametes with 2 or 4 flagella located at the anterior end. Freshwater and seaweed.
The largest department of algae (13 thousand species). A large variety of forms is characteristic: unicellular, filamentous, colonial. Closest to higher plants. All types of thallus differentiation are represented: monadic, coccoid, palmeloid, filamentous, lamellar, siphonal. Representatives are characterized by a pure green color, since chlorophyll a and b predominate among the pigments. In addition, there are pimento: carotenes and xanthophylls. The rigid cell wall is composed of cellulose and pectin substances. Spare substances - starch and oil.
Reproduction is vegetative, asexual and sexual.
They live mainly in freshwater bodies, although there are also marine, soil and terrestrial forms.
The department includes the following classes: Volvocophyceae, Protococcophyceae, Ulotrichophyceae, Conjugatophyceae and Siphonophyceae.
Class volvox (Volvocophyceae)
The most primitive representatives of green algae. They are found as unicellular and colonial forms. A typical representative of unicellular organisms is Chlamidomonas. Chlamydomonas cells have a spherical or ellipsoidal shape and are covered with a membrane of hemicellulose and pectin substances. At the anterior end of the cell, there are two flagella, at the base of which there are two pulsating vacuoles. The entire inner part of the cell is occupied by a protoplast with a large pyrenoid with a starch sphere. Chlamydomonas reproduces asexually with the help of biflagellated zoospores. In addition, sexual reproduction by meiotic cell division with the formation of biflagellated gametes is also possible.
Another typical representative of the Volvox colonial genus Volvox (Volvox). Colonies of volvox have the form of mucous spheres, up to 2 mm in diameter, along the periphery of which there are chlamydomonad-like cells connected by plasmodesmata. Cells in a colony are of two types - vegetative, smaller and more numerous and large generative, scattered between vegetative cells. From the generative cells, parthenogonidia (cells of asexual reproduction) and oogonia (female sex gametes) and antheridia (male reproductive cells) are formed, which carry out the sexual process.
Protococcal class (Protococcophyceae)
These are immobile cells with a dense membrane and colonies of such cells. Most members of the class have a coccoid structure. The cell membrane is cellulose or with an admixture of pectin substances (in the lower representatives it may consist entirely of pectin). Asexual reproduction is carried out using two-flagellate zoospores, the sexual process - using mobile two-flagellate isogametes (isogamy is the process of fusion of identical mononuclear gametes into a zygote.
The only exception is the alga Chlorella, which has no mobile stages during asexual reproduction and does not have a sexual process.
The main representatives: Chlorella, Chlorococcum, Protococcus.
Ulotrichophyceae class
A very diverse group of filamentous and lamellar algae that live in salt and fresh water bodies. The structure of the filaments can be simple or multi-filamentous (heterotrichous). Lamellar forms are single-layer and two-layer.
Asexual reproduction is carried out by mobile zoospores. The sexual process is isogamous.
The main representatives are: Ulothrix, Ulva, Monostroma, etc.
The class combines unicellular and filamentous forms with a special type of sexual process - conjugation.
Conjugation (Latin conjugatio - fusion, connection) is the process of fusion of protoplasts of two vegetative cells that perform the function of gametes.
The fusion takes place through a special conjugation channel. Dividing cells into male and female is sometimes quite difficult and is possible only after some time: a cell with a female potency will be a cell that contains a zygote. But often the fusion of protoplasts occurs in the conjugation canal, which grows with the zygote to the walls of the mother's cells. This phenomenon is observed when the movement of protoplasts along the channel is at the same speed. In this case, they speak of isogamy. In the most developed representatives of couplers, the contents of one cell flows into another to form a zygote. This phenomenon is called heterogamy or anisogamy (from the gr. Hetero - other, anisos - unequal + gamos - marriage). After a dormant period, the zygote germinates and gives rise to one or more seedlings. For the normal course of conjugation, favorable conditions are necessary: warm water (from +15 to +24 ° C) and intense illumination. Conjugation lasts no more than 14 days, from the formation of conjugation canals to the maturation of the zygote.
Also, a distinctive feature of the class is the complete absence of mobile stages in their life cycle. Chromatophores are always pyrenoid, lamellar type and very diverse in shape. Conjugates are cosmopolitan and can be found anywhere in the world, right up to Antarctica. Couples live in fresh and slightly salted water, but there are no typical marine forms among them. In addition, a representative of the class is found on the ground - in mosses, on rocks, damp earth and even on glaciers.
The main representatives: Spirogyra, Zygnema, Mougeotia, etc.
Siphon class (Siphonophyceae)
Representatives of this class have no cellular structure. The thallus of these algae is one giant cell with one or many nuclei. Sometimes such a cell is divided into segments by partitions. This structure is called siphon.
Siphon algae are the oldest group of green algae. More than 90% of the representatives of the group live in the seas, but there are also freshwater forms.
The most typical representatives: Caulerpa, Codium, Dasycladus, Acetobularia.
Indicate the similarities and differences between yellow-green and green algae:
Yellow-green algae Green algae Chloroplasts Chloroplast has a structure typical of ochrophytes. Usually there are several green or yellow-green disc-shaped plastids in the cell. Their color is associated with the absence of fucoxanthin, which is responsible for the golden and brown color in other ochrophytes. Of the carotenoids, tribophyses have α - and β- carotenes (prevailing), vosheriaxanthin, diatoxanthin, diadinoxanthin, heteroxanthin, lutein, violaxanthin, neoxanthin, etc. Chlorophylls - aand c... In tribophytic cells, apart from disc-shaped ones, there are plastids and other forms: lamellar, trough-like, ribbon-like, cupped, stellate, etc. Pyrenoids of the semi-burnt type are found in a few species. The ocellus consists of a number of lipid globules, located at the anterior end of the body in the chloroplast, oriented towards the basal swelling of the flagellum. Chloroplasts of green algae vary in shape and size. In unicellular representatives, they are often cupped with a thickened base. Filamentous representatives can be annular, reticulate, disc-shaped, in the form of spiral-twisted ribbons, etc. Chloroplasts contain one or more pyrenoids. The pyrenoids are immersed in the chloroplast and permeated with thylakoids. In chloroplasts, thylakoids are grouped by 2-6 in the form of plates like in higher plants. In their structure, chloroplasts of green algae are close to those of higher plants. Pigments - chlorophylls aand b, some prasinophytes have chlorophyll c... Carotenoids are always present: β- carotene, lutein (most important), zeaxanthin, violaxanthin, antheraxanthin, neoxanthin. In bryopsida, lutein may be absent or present in small amounts, and then siphonoxanthin, loroxanthin and siphonein become the most important; in some prasinophytes, lutein may be replaced by prazinoxanthin. Siphonoxanthin and loroxanthin are also found in a number of cladophoric species, siphonoxanthin in some Ulva... Cells of some representatives of green algae ( Chlamydomonas nivales, Haematococcus pluvialis, Trentepohlia) are colored red or orange, which is associated with the accumulation of carotenoid pigments and their derivatives outside the chloroplast (this complex was previously referred to as hematochrome). Some siphon algae have colorless amyloplasts in which starch is deposited. The vast majority of green algae contain at least one chloroplast and are capable of autotrophic nutrition. But at the same time, among them there are colorless representatives - obligate heterotrophs, such as Protothecaand Polytoma... A number of green algae are mixotrophs and are able, along with photosynthesis, to use organic compounds dissolved in water, such as sugars, amino acids and other small molecules (osmotrophic absorption), and are also capable of phagotrophic absorption of food particles (a number of prasinophytes). Circular chloroplast DNA molecules look like small balls (nucleoids) and are distributed throughout the chloroplast. DNA never organizes in the form of a single circular nucleoid. Representatives of unicellular, colonial and multicellular, mainly freshwater organisms, unicellular and colonial planktonic algae, including coenobial, unicellular and multicellular forms of benthic algae FlagellaMonad representatives (zoospores and gametes) have two flagella unequal in length and morphology: feathery ciliated hairs are located on the main flagellum, and the lateral flagellum is scourge-shaped. Synzoospores are an exception. Vaucheria, in which numerous pairs of smooth flagella slightly differing in length are located along the surface. Flagella attach to the cell subapically (in the sperm Vaucherialateral attachment). Mastigonemes are synthesized in the cisterns of the endoplasmic reticulum. The short flagellum ends with an acroneme. The basal bodies of the tribophytic flagella are of a typical structure, located at right angles to each other. The radicular system is represented by a transversely striated root - rhizoplast and three microtubular roots, each of which consists of 3-4 microtubules. Monad cells and stages of green algae are isocont, rarely heterocont. The number of flagella per cell can be different - 1,2,4,8,16 and more (up to 120). In Edogonia and some bryopsida, numerous flagella are collected in the form of a corolla at the anterior end of the cell; such cells are called stephanoont. Characteristic feature The transition zone of green algae flagella is the presence of a stellate body in it. Green algae flagella do not have mastigonemes (unlike heterocont), but they can have graceful hairs or scales. According to the location of the microtubular roots, the flagellar apparatus of green algae can be subdivided into two groups, which correspond to the two main phyletic groups of green algae. For the first group, which includes classes Chlorophyceae, Trebuxiophyceaeand Ulvophyceae, a cruciform arrangement of microtubular roots is characteristic, with two microtubular roots located perpendicular to the roots, in which the number of microtubules can vary. This arrangement of microtubular roots is called X-2-X-2. This record reflects the fact that two roots usually contain two microtubules, while the other two roots may have a different number of microtubules (from 3 to 8 for different taxa). In algae from this group, there are three variants of the arrangement of the basal bodies of flagella: the basal bodies are located opposite each other (12-6 hours) (class Chlorophyceae); basal bodies are shifted clockwise (1-7 hours) and do not overlap (class Chlorophyceae); basal bodies are shifted counterclockwise (11-5 hours) and overlap (classes Trebuxiophyceaand Ulvophyceae). For the second group, which includes Charophyta, characterized by an asymmetric arrangement of flagellar roots and the presence of a multilayer structure, which is a complexly organized group of microtubules located near the basal bodies. A very similar multilayer structure is known for the flagellar spermatozoa of higher plants. It is also found in zooids in trentepoliaceae, in trebuxia algae. Myrmecia israeliensisand some prasinophytes. The multilayer structure appeared sporadically in other groups of algae, for example, in glaucocystophytes, euglena Eutreptiella, in some dinophytes. In addition to microtubular roots, green algae may have a rhizoplast, which extends from the basal bodies to the nucleus. Cell wall In species with amoeboid, monad and palmeloid organization, the cell wall is absent, they are covered only by the cytoplasmic membrane and can easily change shape. Sometimes "naked" cells are located inside houses, the walls of which can be painted brown with manganese and iron salts. The overwhelming majority of tribophytic species have a cell wall that is whole or in two parts. In its composition, studied by Tribonemaand Vaucheria, cellulose predominates and contains polysaccharides, consisting mainly of glucose and uronic acids. In young cells, the membrane is thin; with age, it thickens. Iron salts can be deposited in it, the compounds of which color it in various shades of brown and red. More often, silica is present in the cell wall, giving it hardness and shine. It can also be encrusted with lime and sculptured in various ways (spines, cells, warts, bristles, denticles, etc.). In attached forms, an outgrowth of the shell can form - a leg with an attachment sole. In filamentous algae with bivalve membranes, when the filaments break down, the cell membranes fall apart into H-shaped fragments, which are tightly connected halves of the membranes of two neighboring cells. During the growth of filaments, an H-shaped fragment of the cell wall of two adjacent daughter cells is embedded between the two halves of the mother cell's membrane. As a result, each of the daughter cells is half covered by the old membrane of the mother cell and half by the newly formed membrane. In the chlorophytic and prasinophytic classes, algae are found in which the cells are naked and devoid of a cell wall. In mesostigmoids and many prasinophytes, organic scales are deposited on top of the plasmalemma. They are found in the mobile cells of a number of ulvic and charove algae. The presence of organic scales on motile cells is apparently a primitive sign. More progressive is the appearance of theca in prasinophytes and then in chlorophycia. Theca in chlorophyzia consists of glycoproteins rich in hydroxyproline and associated with various oligosaccharides. In siphonal algae, cellulose is either absent in the cell wall, then the main component is xylan (for example, Halimeda), or is present as an impurity to mannal or xylan. The composition of the fibrillar part of the cell wall can vary depending on the phase of development. For example, in the shell of a sporophyte Bryopsismannan is present, and the gametophyte contains xylan and cellulose. Chemical composition the shell can also change in different parts of the thallus. For example, in Codiumin the old parts, mannan is present in the shell, and in the young, undifferentiated parts, glucan is present. In most green algae, the main component of the cell wall is cellulose. It is synthesized by the enzyme cellulose synthetase, which is built into the cell plasma membrane. From 6 to 10 cellulose synthetase molecules are grouped into subunits, which are then combined into terminal complexes. In green algae, two types of terminal complexes are known - rosette (in harophytes) and linear (in chlorophytic, ulvophytic). Rosette complexes, as in higher plants, consist of 6-8 subunits. Among charophytes, such complexes were found in Spirogyra, Micrasterias, Nitellaand Coleochaete... Some coccoid green algae have an additional layer in the shell, consisting of a sporopollenin-like substance. Reproduction Most yellow-green algae are known to reproduce vegetatively and asexually. Vegetative reproduction is carried out by dividing cells in half, disintegration of colonies and multicellular thalli into parts. With asexual reproduction, amoeboids, zoospores, synzoospores, hemizoospores, hemiautospores, autospores, aplanospores can form. Zoospores are "naked" and usually pear-shaped, with two flagella. The sexual process (iso-, hetero- and oogamous) is described in a few representatives. On the offensive unfavorable conditions the formation of cysts is observed. Cysts (statospores) are endogenous, mononuclear, less often multinucleated. Their wall often contains silica and consists of two unequal, or less often equal parts. Reproduction of green algae is vegetative, asexual and sexual. Vegetativereproduction in unicellular organisms, devoid of a membrane, occurs by dividing the cell in half (for example, Dunaliella), in colonial and multicellular organisms - by fragments of the thallus, in charovae - by special rhizoidal and stem nodules. Asexualreproduction in green algae is widespread. During asexual reproduction, the forming zoospores can be naked or covered with a rigid cell wall. A coating of scales, such as in many prasinophytic motile reproductive cells, many ulvophytic and harophytic ones, is rarely found in chlorophytic reproductive cells. After a period of movement, zoospores stop, lose their flagella, round off (in the case of naked zoospores) and develop into vegetative individuals. Aplanospores (immobile spores) are spores of asexual reproduction, which lack flagella, but have contractile vacuoles. Aplanospores are considered as cells in which further development into zoospores is suspended. Autospores, which are reduced copies of immobile vegetative cells, lack contractile vacuoles. The formation of autospores correlates with the conquest of terrestrial conditions in which water cannot always be present in sufficient quantities. Sexual processrepresented by various forms: hologamy, conjugation, isogamy, heterogamy, oogamy. Usually there are 1-2 of them per cell, sometimes more. The Golgi apparatus has a peculiar structure. Dictyosomes are small, contain 3-7 cisterns. The reserve nutrients are oils, some have volutin, chrysolaminarin and leucosin. Only freshwater monadic and palmeloid representatives have contractile (pulsating) vacuoles. Since the concentration of salts in the cell is higher than in the reservoir, water enters the cell, and its excess is removed by contractile vacuoles. Usually, the cell contains two contractile vacuoles located at the base of the flagella. They are shortened alternately. Nucleus There is one nucleus, less often there are many nuclei; in cenotic representatives, the cells are always multinucleated. The details of mitosis have been studied in detail only in Vaucheria... Her mitosis is closed, with centrioles located at the poles outside the nucleus. No kinetochores were found. During anaphase, the interpolar microtubules of the spindle are greatly lengthened, which leads to a significant distance of daughter nuclei from each other. The nuclear membrane is preserved, therefore, in the telophase, the daughter nuclei look like a dumbbell. It is believed that such mitosis is not typical for the entire tribophytic group. the nucleus (sometimes several nuclei) is usually located in the wall layer of protoplasm or, suspended on plasma filaments, is located in the central part of the cell. mitosis can be closed, i.e. the nuclear membrane remains intact during mitosis. Trebuxia algae have an unusual form of semi-closed mitosis. This is the so-called metacentric mitosis. With him, the centrioles during metaphase are located in the region of the metaphase plate, and not at the poles of the spindle. In charophytes, mitosis is open, the nuclear membrane disappears by the beginning of mitosis and then appears in the telophase, as in higher plants. In the columns of the table, write the generic names of the most famous forms of algae from various divisions of distribution in various environmental conditions: algae green color structure Different ecological conditions Fresh water bodies Cold seas Warm seas Hot springs Tree bark rocks soil Generic names of the most famous forms of algae from different departments Chlorella, flexible lustrous,ulotrix, microcystis, oscillatoriaceae, volvox, vosheria, cladophora, nitela, spirogyra, scenedesmus, chlamydomonas, pandorina, spirulina, lingbia, nostok, anabena, aphanizomenonrivularia, gleotrichia, stigonema, paranasheda, astazellena , dermocarpa, prochlotrix KelpOscillatorium, Anfelcia, Cladophora, Fucus, Cystosira, Prochloronmerismopedia, Dermocarpaspirulina, Lingbia, Anabena, Afanizomenon, Rivulyaria Ulva Cystosira Phyllofora Oscillatoriacetabularia Caulerpa Cladophorae Macrostyloronium Porphyria Prochoronmerismopedia OscillatoriumMastigocladus PleurococcusChlorella Oscillatorium Gleocaps Macrocystis Oscillatorium Gleocaps Calotrix Stygonema OscillatoriumLingbia vosheria Hchlorella Gleocaps Nostock stigonema
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In the past, algae were considered primitive plants (without specialized conductive or vascular tissues); they were allocated to the subdivision of algae (Algae), which, together with the subdivision of fungi (Fungi), constituted the department of thallus (layered), or lower plants (Thallophyta), one of the four departments of the plant kingdom (some authors use the zoological term instead of the term "department" a type"). Further, algae were divided by color - into green, red, brown, etc. Color is a strong enough, but not the only basis for the general classification of these organisms. The types of formation of their colonies, methods of reproduction, peculiarities of chloroplasts, cell walls, storage substances, etc. are more important for the isolation of various groups of algae. The old systems usually recognized about ten such groups, which were considered classes. One of the modern systems refers to "algae" (this term has lost its classification meaning) eight types (divisions) of the kingdom of protists (Protista); however, this approach is not recognized by all scientists.
Green algae division (type) Chlorophyta of the protist kingdom
They are usually grass green (although they can range from pale yellow to nearly black in color) and have the same photosynthetic pigments as normal plants.
Most are microscopic freshwater forms. Many species grow on soil, forming felt-like deposits on its wet surface. They are unicellular and multicellular, form filaments, spherical colonies, leaf-like structures, etc.
Cells are mobile (with two flagella) or immobile. Sexual reproduction - different levels of difficulty depending on the species. Several thousand species have been described. The cells contain a nucleus and several well-defined chloroplasts.
One of the well-known genera is Pleurococcus, a unicellular alga that forms green plaques often seen on the bark of trees.
The genus Spirogyra is widespread - filamentous algae that form long filaments of mud in streams and cold rivers. In the spring, they float as sticky yellowish-green clusters on the surface of ponds.
Cladophora grows as soft, highly branching "bushes" that attach to rocks near river banks.
Basiocladia forms a green coating on the back of freshwater turtles.
The water mesh (Hydrodictyon), which is composed of many cells, which lives in stagnant waters, in structure really resembles a "string bag".
Desmidia - unicellular green algae that prefer soft swamp water; their cells are distinguished by a bizarre shape and a beautifully ornamented surface.
In some species, cells are connected in filamentous colonies. In the free-swimming colonial alga Scenedesmus, sickle-shaped or oblong cells are united in short chains. This genus is common in aquariums, where its mass reproduction results in a green "fog" in the water.
The largest green alga is sea lettuce (Ulva), a leaf-shaped macrophyte.
Red algae (crimson) make up the Rhodophyta division (type) of the protist kingdom
Most of them are marine leafy, bushy or crustal macrophytes that inhabit below the low tide line. Their color is predominantly red due to the presence of the phycoerythrin pigment, but can be purple or bluish. Some scarlet species are found in fresh water, mainly in streams and clear fast rivers. Batrachospermum is a highly branched algae, gelatinous to the touch, consisting of brownish or reddish bead-like cells. Lemanea is a brush-like form, often growing in fast-flowing rivers and waterfalls, where its thalli attach to rocks. Audouinella is a filamentous algae found in small rivers. Irish moss (Chondrus cripus) is a common marine macrophyte. The scarlet cells do not form motile cells. Their sexual process is very complex, and one life cycle includes several phases.
Brown algae make up the Phaeophyta division (type) of the protist kingdom
Almost all of them are sea dwellers. Only a few species are microscopic, and the largest algae in the world are found among macrophytes. The latter group includes kelp, macrocystis, fucus, sargassum and lessonia ("sea palms"), which are most abundant along the coasts of cold seas. All brown algae are multicellular. Their color varies from greenish-yellow to dark brown and is due to the pigment fucoxanthin. Sexual reproduction is associated with the formation of mobile gametes with two lateral flagella. Instances that form gametes are often completely different from organisms of the same species, which reproduce only by spores.
Diatoms (diatoms)
They are combined into the class Bacillariophyceae, which, in the classification used here, is included, along with golden and yellow-green algae, in the Chrysophyta division (type) of the protist kingdom. Diatoms are a very large group of unicellular marine and freshwater species. Their color is from yellow to brown due to the presence of the pigment fucoxanthin. The protoplast of diatoms is protected by a box-shaped silica (glass) shell - a shell consisting of two valves. The hard surface of the valves is often covered with a complex pattern of striae, tubercles, pits, and ridges characteristic of the species. These shells are some of the most beautiful microscopic objects, and the clarity of their pattern is sometimes used to check the resolving power of the microscope. Usually, the valves are pierced with pores or have a gap called a seam. The cell contains the nucleus. In addition to cell division in two, sexual reproduction is also known. Many diatoms are free-floating forms, but some are attached to underwater objects with slimy legs. Sometimes cells join together in strands, chains, or colonies. There are two types of diatoms: cirrus with elongated bilaterally symmetric cells (they are most abundant in fresh waters) and centric, the cells of which, when viewed from the valve, look round or polygonal (they are most abundant in the seas).
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