16.06.2019
Edible algae - types, benefits and harms. Types of algae and characteristics of their varieties Algae definition for children
Question 1. What is the structure of a plant cell?
A plant cell consists of a cell wall (shell), cytoplasm and organelles that are in the cytoplasm: the nucleus, vacuoles with cell sap and plastids.
Question 2. What are plastids?
Plastids are membranous organelles found in photosynthetic organisms ( higher plants, lower algae, some unicellular organisms).
Question 3. What plastids do you know?
Chloroplast, leukoplast, chromoplast.
Question 4. What are pigments?
PIGMENTS - colored substances of the tissues of organisms involved in their vital activity. Determine the color of organisms in plants they participate in photosynthesis (chlorophylls, carotenoids), protect the body from the harmful effects of ultraviolet rays (in plants - carotenoids, flavonoids). Some pigments are used in Food Industry and medicine.
Question 5. What is called plant tissue?
Plant tissue is a group of cells that have a common origin, perform one or more functions and occupy their own position in the plant body. Plant organs are made up of different tissues.
Laboratory work No. 9. The structure of green unicellular algae.
1. Place a drop of “blooming” water on a microscope slide, cover with a cover slip.
2. Consider unicellular algae at low magnification. Look for Chlamydomonas (a pear-shaped body with a pointed front end) or chlorella (a spherical body).
3. Pull some of the water out from under the coverslip with a strip of filter paper and examine the algae cell at high magnification.
4. Find the shell, cytoplasm, nucleus, chromatophore in the algae cell. Pay attention to the shape and color of the chromatophore.
Chlorella chromatophore has the appearance of a strongly carved bowl, starch is deposited in it. Chlomidomonas chromatophore has a characteristic cup-shaped shape. Due to such invaginations of the chromatophore, the area of \u200b\u200bdistribution of chloroplasts increases.
5. Draw a cell and label the names of its parts. Check the correctness of the drawing according to the drawings of the textbook.
With an increase, I saw (a) almost the same structure of algae as in the figure in the textbook.
Conclusion: we examined the structure of green unicellular algae using the example of chlomidomonas and chlorella. These algae are composed of a cell membrane, cytoplasm, nucleus and chromatophore. Chlamydomonas also has a red "eye", which is sensitive to light, and flagella, with the help of which Chlomidomonas moves (unlike chlorella).
Question 1. Why are algae classified as lower plants?
Algae belong to the lower plants, because they have no roots, no stems, no leaves.
Question 2. Where do green unicellular algae live?
Green algae live in salt and fresh water, on land, on the surface of trees, stones or buildings, in damp, shady places. Species living out of water are dormant during drought.
Question 3. What is the structure of chlamydomonas?
Chlamydomonas is a pear-shaped unicellular green algae. It moves in water with the help of two flagella located at the anterior, narrower end of the cell.
Outside, chlamydomonas is covered with a transparent membrane, under which there is a cytoplasm with a nucleus, a red "eye" (a light-sensitive red body), a large vacuole filled with cell sap, and two small pulsating vacuoles. Chlorophyll and other pigments in chlamydomonas are located in a large cup-shaped plastid, which in algae is called a chromatophore (translated from Greek - “carrying light”). The chlorophyll contained in the chromatophore gives the green color to the entire cell.
Question 4. Where do they live and what structure do green multicellular algae have?
In multicellular representatives of green algae, the body (thallus) has the form of filaments or flat leaf-shaped formations. In flowing waters, you can often see bright green clusters of silky threads attached to underwater rocks and snags. It is a multicellular filamentous green alga ulotrix. Its threads consist of a number of short cells. In the cytoplasm of each of them there is a nucleus and a chromatophore in the form of an open ring. The cells divide and the thread grows.
In stagnant and slowly flowing waters, slippery bright green lumps often float or settle to the bottom. They look like cotton wool and are formed by clusters of filamentous algae spirogyra. The elongated cylindrical cells of spirogyra are covered with mucus. Inside the cells - chromatophores in the form of spirally twisted ribbons.
Multicellular green algae also live in the waters of the seas and oceans. An example of such algae is ulva, or sea lettuce, about 30 cm long and only two cells thick.
The most complex structure in this group of plants has charophytes living in freshwater reservoirs. These numerous green algae appearance resemble horsetails. Chara algae nitella, or flexible algae, are often grown in aquariums.
Question 5. Where do brown algae live and what structure do they have?
Brown algae are mainly marine plants. General outward sign these algae - yellowish-brown color of thalli.
Brown algae are multicellular plants. Their length ranges from microscopic to gigantic (several tens of meters). Thallus of these algae can be filamentous, spherical, lamellar, bushy. Sometimes they contain air bubbles that keep the plant upright in the water. Brown algae are attached to the ground by rhizoids or by a disc-like overgrown base of the thallus.
Some brown algae develop groups of cells that can be called tissues.
In our Far Eastern seas and the seas of the North Arctic Ocean large brown algae kelp, or seaweed, grows. In the coastal strip of the Black Sea, the brown alga cystoseira is often found.
Question 6. Where do they live and what structure do red algae have?
Red algae, or purple algae, are basically multicellular marine plants. Only a few species of crimson are found in fresh water. Very few of the red algae are unicellular.
The sizes of crimson usually range from a few centimeters to a meter in length. But among them there are also microscopic forms. The cells of red algae, in addition to chlorophyll, contain red and blue pigments. Depending on their combination, the color of crimson varies from bright red to bluish-green and yellow.
Externally, red algae are very diverse: filamentous, cylindrical, lamellar and coral-like, dissected and branched to varying degrees. Often they are very beautiful and whimsical.
In the sea, red algae are found everywhere in the most different conditions. They usually attach themselves to rocks, boulders, man-made structures, and sometimes other algae. Due to the fact that red pigments are able to capture even very a large number of light, purple can grow at considerable depths. They can be found even at a depth of 100-200 m. Phyllophora, porphyry, etc. are widespread in the seas of our country.
Question 7. What is a thallus?
Thallus, or thallus, is the vegetative body of fungi, algae, lichens, some bryophytes, not differentiated into organs and not having real tissues.
Question 8. What is a chromatophore?
Chromatophores - membrane intracellular structures in the form of vesicles, in which light-sensitive pigments are located and pass through initial stages photosynthesis in some photosynthetic bacteria.
Question 9. What are rhizoids? Why can't they be called roots?
Rhizoids - outgrowths of the lower part of algae, lichens, horsetails, club mosses, mosses, which are filamentous formations that serve for attachment. Unlike roots, a much more complex structure, consisting of many elements and much more complexly organized, rhizoids are formed by one or, at best, several cells.
Question 10. What is the importance of algae in nature?
Algae feed on fish and other aquatic animals. Algae absorb carbon dioxide from water and, like all green plants, release oxygen, which is breathed by living organisms that live in water. Algae produce a huge amount of oxygen, which is not only dissolved in water, but also released into the atmosphere.
Question 11. How does a person use algae?
Man uses seaweed in chemical industry. They produce iodine, potassium salts, cellulose, alcohol, acetic acid and other products. Algae are used as fertilizers and consumed on. livestock feed. From some types of red algae, the gelatinous substance agar-agar is obtained, which is necessary in the confectionery, bakery, paper and textile industry. Microorganisms are grown on agar-agar for use in laboratory research.
In many countries, algae are used for cooking variety of dishes. They are very useful, as they contain a lot of carbohydrates, vitamins, and are rich in iodine.
Laminaria (seaweed), ulva (sea lettuce), porphyry, etc. are especially often eaten. Chlamydomonas, chlorella and other unicellular green algae are used in biological wastewater treatment. Excessive growth of algae, for example in irrigation canals or fish ponds, can be harmful. Therefore, canals and reservoirs have to be periodically cleared of these plants.
Think
Why even in multicellular algae that have big sizes, absent vascular system?
Algae live in a nutrient "solution" and can absorb it all over the surface. Therefore, they do not have such organs as trunks, stems and branches, and there is no vascular system that performs a transport function in terrestrial plants, because they do not need to move water and nutrients through their bodies. Everything the algae needs comes to them from the outside right where these substances will be used.
Quests for the curious
Carefully remove green plaque from the bark of several trees. Prepare slides and examine them under a microscope. Consider algae cells that form a green coating. Try to establish whether it is formed by one or more types of algae.
Conclusion: they form green plaques in the lower part of trees, on fences, etc., various unicellular green algae that have adapted to terrestrial life (for example, in our case it is pleurococcus and chlorococcus). Under the microscope, single cells or groups of green algae cells are visible. The only source of moisture for these algae is precipitation(rain and dew). With a lack of water or low temperatures Pleurococcus and other terrestrial algae can spend part of their lives dormant. In our case, we managed to find these two algae on different trees.
SEAWEED
(algae), a vast and heterogeneous group of primitive, plant-like organisms. With few exceptions, they contain the green pigment chlorophyll, which is essential for nutrition through photosynthesis, i.e. synthesis of glucose from carbon dioxide and water. Colorless algae are very rare, but in many cases the green chlorophyll is masked by pigments of a different color. In fact, among the thousands of species included in this group, one can find forms painted in any of the tones of the solar spectrum. Although algae are sometimes referred to as the most primitive organisms, this opinion can only be accepted with significant reservations. Indeed, many of them lack complex tissues and organs comparable to those well known in seed plants, ferns, and even mosses and liverworts, but all the processes necessary for the growth, nutrition and reproduction of their cells are very, if not completely, similar to occurring in plants. Thus, physiologically, algae are quite complex. Algae are the most numerous, most important for the planet and the most widespread photosynthetic organisms. There are many of them everywhere - in fresh waters, on land and in the seas, which cannot be said, for example, about liverworts, mosses, ferns or seed plants. Algae can often be seen with the naked eye as small or large patches of green or otherwise colored foam ("mud") on the surface of the water. On soil or tree trunks, they usually appear as green or blue-green slime. In the sea, thalli of large algae (macrophytes) resemble red, brown and yellow shiny leaves of various shapes.
Morphology and anatomy. The sizes of algae vary widely - from microscopic forms with a diameter or a thousandth of a centimeter in length to sea giants more than 60 m long. Many algae are unicellular or consist of several cells that form loose aggregates. Some are strictly organized colonies of cells, but there are also true multicellular organisms. Cells can be connected end-to-end, forming chains and threads - both branched and non-branched. The whole structure sometimes looks like a small disk, a tube, a mace, and even a tree, and sometimes it resembles a ribbon, a star, a boat, a ball, a leaf, or a tuft of hair. The surface of the cells may be smooth or covered with a complex pattern of spines, papillae, pits, and ridges. In most algae, cells general structure similar to the green cells of plants, such as corn or tomato. A rigid cell wall, consisting mainly of cellulose and pectin, surrounds the protoplast, in which the nucleus and cytoplasm are distinguished with special organelles included in it - plastids. The most important of these are chloroplasts containing chlorophyll. The cell also has fluid-filled cavities - vacuoles that contain dissolved nutrients, mineral salts and gases. However, this cell structure is not characteristic of all algae. In diatoms, one of the most important components of the cell wall is silica, which creates, as it were, a glass shell. The green color of chloroplasts is often masked by other substances, usually pigments. A small number of algae do not have a rigid cell wall at all.
Locomotion. Many aquatic vegetative cells and algae colonies, as well as some types of their reproductive cells, move fairly quickly. They are equipped with one or more whip-like appendages - flagella, the beating of which pushes them through the water column. Some algae lacking a cell wall are able to stretch parts of their body forward, pull the rest towards them and, due to this, "crawl" along solid surfaces. Such a movement is called amoeboid, since the well-known amoebae move in approximately the same way. Rectilinear or zigzag locomotion of diatoms - owners of a solid cell wall - is probably due to water currents created by various jet-like movements of their cytoplasm. Sliding, crawling, wavy movement of algae more or less rigidly attached to the substrate is usually accompanied by the formation and liquefaction of mucus.
Reproduction. Almost all unicellular algae are able to reproduce simple division. The cell divides in two, both daughter cells do the same, and this process, in principle, can go on ad infinitum. Since the cell dies only as a result of an "accident", one can speak of a kind of immortality. A special case- cell division in diatoms. Their shell consists of two halves (shutters) that fit into each other, like two parts of a soap dish. Each daughter cell receives one parent leaf, and completes the second itself. As a result, in a diatom, one valve may be new, and the second - inherited from a distant ancestor. The protoplast of some vegetative cells is able to divide to form mobile or immobile spores. Of these, after a long or short dormant period, a mature algae develops. This is one form of asexual reproduction. During sexual reproduction in algae, male and female germ cells (gametes) are formed. The male gamete fuses with the female, i.e. fertilization occurs and a zygote is formed. The latter, usually after a dormant period, lasting from several weeks to several years, depending on the type of algae, begins to grow and eventually gives rise to an adult. Gametes vary greatly in size, shape, and motility. In some algae, male and female gametes are structurally similar, while in others they clearly differ, i.e. are sperm and eggs. Thus, sexual reproduction in algae has many forms and levels of complexity.
DISTRIBUTION AND ECOLOGY
Aquatic algae. It is difficult to find a place on the planet where there would be no algae. Usually they are considered aquatic organisms, and, indeed, the vast majority of algae lives in puddles and ponds, rivers and lakes, seas and oceans, and in certain seasons they can become very abundant there. Algae attach themselves to rocks, stones, pieces of wood, aquatic plants, or float freely as part of the plankton. At times, this suspension of them, including billions of microscopic forms, reaches the consistency of pea soup, filling the vast expanses of lakes and seas. This phenomenon is called "algal bloom" of water. The depth at which algae can be found depends on the transparency of the water, i.e. its ability to pass the light necessary for photosynthesis. Most algae are concentrated in the surface layer a few decimeters thick, but some green and red algae are found at much deeper depths. Some species are able to grow in the ocean at a depth of 60-90 m. Some algae, even frozen in ice, can remain viable in a state of suspended animation for many months.
Soil algae. Despite their name, algae are not only found in water. For example, there are a lot of them in the soil. In 1 g of well-manured soil, approx. 1 million of their individual copies. Those that are concentrated on the surface of the soil and directly below it feed by photosynthesis. Others live in darkness, are colorless and absorb dissolved food from environment, i.e. are saprophytes. The main group of soil algae are diatoms, although green, yellow-green and golden algae are also abundant in places in this habitat.
snow algae are often found in large numbers in the ice and snow of the Arctic and Antarctic deserts, as well as the Alpine highlands. In the cold polar seas, they grow just as well as in hot springs. The so-called "red snow" is the result of the presence of microscopic algae in it. Snow algae are colored red, green, yellow and brown.
Other types of algae. Algae live in many other habitats, sometimes quite unusual ones. They are found, for example, on the surface or inside aquatic and terrestrial plants. Settling in the tissues of many tropical and subtropical species, they grow so actively here that they can damage their leaves: in the tea bush, this disease is called "rust". IN temperate climate algae often cover the bark of trees with a green coating, usually on the shaded side. Some green algae form symbiotic associations with certain fungi; such associations are special, completely independent organisms called lichens. A number of small forms grow on the surface and inside larger algae, and one genus of green algae grows only on the shell of turtles. Green and red algae are found in the hair follicles of three-toed sloths that inhabit the tropical rainforests of Central and South America. Algae also grow on the body of fish and crustaceans. Perhaps some flatworms and coelenterates may not swallow food at all, since they receive it from the green algae that live in their body.
limiting environmental factors. Although algae are found almost everywhere, each of their species needs a certain combination of light, humidity and temperature, the presence of the necessary gases and mineral salts to live. Photosynthesis requires light, water and carbon dioxide. Some algae tolerate significant periods of near-drying, but they still require water to grow, serving as the only habitat for the vast majority of forms. The content of oxygen and CO2 in water bodies varies greatly, but algae usually have enough of them. Large amounts of algae in shallow reservoirs sometimes consume so much oxygen overnight that they cause a mass death of fish: it becomes unable to breathe. For the growth of algae, compounds of nitrogen and many other chemical elements dissolved in water are necessary. The concentration of these mineral salts in the water column is much lower than in many soils, but for a number of species it is usually sufficient for mass development. Sometimes the growth of algae is sharply limited due to the lack of a single element: diatoms, for example, are rare in water containing little silicates. Attempts have been made to divide algae into ecological groups: aquatic, soil, snow or bark forms, epibionts, and so on. Some algae grow and reproduce only at a strictly defined time of the year, i.e. can be considered annuals; others are perennials, in which only reproduction is confined to a certain time. A number of unicellular and colonial forms complete the vegetative and reproductive phases of their life cycle in just a few days. All these phenomena, of course, are connected not only with the heredity of organisms, but also with various factors their environment, however, the elucidation of the exact relationships within the emerging ecological groups of algae is a matter for the future.
ALGAE IN THE PAST
It is likely that some forms of algae already existed in the earliest geological epochs. Many of them, judging by modern species, could not leave fossils due to the peculiarities of their structure (lack of solid parts), therefore it is impossible to say what exactly they were. Fossil forms of the main current groups of algae, except for diatoms and a few others, have been known since the Paleozoic (570-245 million years ago). The most abundant in that era were probably green, brown, red, and charophytic algae that lived in the seas and oceans. Indirect evidence of the early appearance of algae on our planet is the scientifically proven existence in the Paleozoic of many marine animals that were supposed to feed on organic matter. Its primary source for them most likely was photosynthetic algae, consuming only mineral substances.
Fossil diatoms. Fossil diatoms (diatoms) in the form of a special rock - the so-called. diatomite - found in many regions. Diatomaceous earth comes in both marine and freshwater origin. In California, for example, there is its deposit with an area of about 30 km2 and a thickness of almost 400 m. It consists almost exclusively of diatom shells. In 1 cm3 of diatomite, there are up to 650,000 of them.
The evolution of algae. Many groups of algae seem to have changed little since their origin. However, certain species of them, once very abundant, are now extinct. As far as we know, there have been no major fluctuations in species diversity and total abundance of algae throughout the history of the Earth. Aquatic habitats have changed little over many millions of years, and modern forms Algae have certainly been around for a very long time. It is unlikely that any large group of algae appeared later than the Paleozoic or early Mesozoic (240 million years ago).
ECONOMIC ASPECTS
The harm caused. Some algae cause economic damage, or at least cause great trouble. They pollute water sources, often giving it an unpleasant taste and smell. Some massively multiplied species can be easily identified by their specific "aroma". Fortunately, now there are so-called. algicides - substances that effectively kill algae and at the same time do not impair the quality drinking water. To combat algae in fish ponds, measures such as increasing the "flow" of the system, its shading and resuspension are also used. Crayfish, for example, keep the water cloudy enough to greatly slow down the growth of algae. Some algae, especially during periods of their "bloom", spoil the places reserved for swimming. Many marine macrophytes break away from the substrate during storms and are thrown by waves and wind onto the beach, literally flooding it with their rotting mass. In their dense clusters, fish fry can get entangled. Several species of algae, when ingested by animals, cause poisoning, sometimes fatal. Others turn out to be a real disaster in greenhouses or damage the leaves of plants.
Benefits of algae. Algae have many beneficial properties.
Food for aquatic animals. Algae can be considered the primary food source for all aquatic animals. Due to the presence of chlorophyll, they synthesize organic substances from inorganic substances. Fish and other aquatic animals consume this organic matter directly (by eating algae) or indirectly (by eating other animals), so algae can be considered the first link in almost all food chains in reservoirs.
food for man. In many countries, especially in the East, people eat several types of large algae. Their nutritional value is low, but the content of vitamins and minerals in such "greens" can be quite high.
agar source. From some seaweeds, agar is obtained - a gelatinous substance used to make jelly, ice cream, shaving cream, salads, emulsions, laxatives, and also for growing microorganisms in laboratories.
Diatomaceous earth. Diatomaceous earth is used in the composition of abrasive powders and filters, and also serves as a heat-insulating material that replaces asbestos.
Fertilizer. Algae is a valuable fertilizer, and marine macrophytes have been used for plant nutrition since ancient times. Soil algae can largely determine the fertility of the site, and the development of lichens on bare stones is considered the first stage of the soil formation process.
Aquatic cultures. Biologists have long been growing algae in laboratories. At first they were grown in small transparent cups of pond water in sunlight, and in Lately for this, special culture media are used with a certain amount of mineral salts and special growth substances, as well as regulated sources of artificial light. Some algae have been found to require very specific conditions for optimal development. The study of such laboratory cultures has greatly expanded our knowledge of the growth, nutrition, and reproduction of these organisms, as well as of their chemical composition. Now in different countries pilot plants have already been built, which are a kind of huge aquariums. On them, under strictly controlled conditions, using complex equipment, experiments are being carried out to clarify the prospects for the use of algal cultures. As a result, it has been proven that the production of dry matter of algae per unit area can be much higher than that of current agricultural plants. Some of the species used, such as the single-celled green alga Chlorella, yield "crops" containing up to 50% edible protein. It is possible that future generations of people, especially in densely populated countries, will use artificially grown algae.
CLASSIFICATION OF ALGAE
In the past, algae were considered primitive plants (without specialized conductive or vascular tissues); they were isolated in the subdivision of algae (Algae), which, together with the subdivision of fungi (Fungi), constituted the division of thallus (layer), or lower plants (Thallophyta), one of the four divisions of the plant kingdom (some authors use the zoological term instead of the term "department" type"). Further, algae were divided by color - into green, red, brown, etc. Color is quite strong, but not the only basis for the general classification of these organisms. The types of formation of their colonies, methods of reproduction, features of chloroplasts, cell wall, reserve substances, etc. are more essential for the selection of various groups of algae. The old systems usually recognized about ten such groups, which were considered classes. One of modern systems refers to "algae" (this term has lost its classification value) eight types (divisions) of the kingdom of protists (Protista); however, this approach is not recognized by all scientists.
green algae make up a department (type) Chlorophyta protist kingdoms. They are usually the color of grass green (although the color may vary from pale yellow to almost black), and their photosynthetic pigments are the same as those of ordinary plants. Most are microscopic freshwater forms. Many species grow on the soil, forming felt-like raids on its moist surface. They are unicellular and multicellular, form filaments, spherical colonies, leaf-shaped structures, etc. Cells are motile (with two flagella) or immobile. sexual reproduction - different levels difficulty depending on the type. Several thousand species have been described. The cells contain a nucleus and several distinct chloroplasts. One of the well-known genera is Pleurococcus, a single-celled algae that forms the green patches often seen on tree bark. The genus Spirogyra is widespread - filamentous algae that form long fibers of mud in streams and cold rivers. In spring, they float in sticky, yellowish-green clumps on the surface of ponds. Cladophora grows in the form of soft, strongly branched "bushes" that attach themselves to stones along the banks of rivers. Basiocladia forms a green coating on the back of freshwater turtles. The water mesh (Hydrodictyon) consisting of many cells, living in stagnant waters, really resembles a "string bag" in structure. 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, the cells are connected in filamentous colonies. In the free-floating colonial algae Scenedesmus, sickle-shaped or oblong cells are arranged in short chains. This genus is common in aquariums, where its mass reproduction leads to the appearance of a green "fog" in the water. The largest green algae is sea lettuce (Ulva), a leaf-shaped macrophyte.
VOLVOX- colonial freshwater green algae. The colony looks like a hollow ball (no more than 3 mm in diameter), the surface of which is formed by cells interconnected by strands of protoplasm. It is assumed that colonial forms of this kind are one of the links connecting unicellular and multicellular organisms. Daughter ones are formed inside the parent colony.
Umbrella thalli green algae Acetabularia mediterranean. This genus is widely used in genetic research.
red algae(crimson) make up a department (type) Rhodophyta protist kingdoms. Most of them are marine leafy, bushy or crusty macrophytes living below the low tide line. Their color is predominantly red due to the presence of the pigment phycoerythrin, but may be purple or bluish. Some purples are found in fresh water, mainly in streams and clear fast rivers. Batrachospermum is a gelatinous, highly branched algae composed of brownish or reddish, bead-like cells. Lemanea is a brush-like form often growing in fast-flowing streams and waterfalls where its thalli attach to rocks. Audouinella is a filamentous alga found in small rivers. Irish moss (Chondrus cripus) is a common marine macrophyte. Purples do not form mobile cells. Their sexual process is very complex, and one life cycle includes several phases.
ALMOST ALL RED ALGAE grow in the seas. Their foliose, bushy or crusty life forms painted in various shades of red.
brown algae make up a department (type) Phaeophyta protist kingdoms. Almost all of them are inhabitants of the sea. Only a few species are microscopic, and among the macrophytes are the largest algae in the world. The latter group includes 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 motile gametes with two lateral flagella. Instances that form gametes are often completely different from organisms of the same species that reproduce only by spores.
SEA MACROPHYTES are the largest algae in the world. These multicellular organisms, more than any other algae, resemble green plants: their thalli are often branched, outwardly similar to leafy stems. Another feature they have in common with plants is the need for sunlight for photosynthesis. That is why they cannot grow at great depths where the sun's rays do not penetrate. Some species of these algae are free-swimming, while others are attached to rocks in the tidal zone or at the bottom of the sea. The picture shows brown algae.
diatoms(diatoms) are combined into a class Bacillariophyceae, which, in the classification used here, is included, together 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 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 one of the most beautiful microscopic objects, and the clarity of distinguishing their patterns is sometimes used to test the resolving power of a 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-swimming forms, but some are attached to underwater objects with slimy stalks. Sometimes cells are combined into threads, chains or colonies. There are two types of diatoms: cirrus with elongated bilaterally symmetrical cells (they are most abundant in fresh waters) and centric, whose cells, when viewed from the valve, look rounded or polygonal (they are most abundant 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.
DIATOMEA- an extensive group of unicellular marine and freshwater algae. Cells of some of their species are connected in straight or zigzag chains. Unlike other algae, diatoms are protected by a silica shell of two valves, one of which is larger than the other and covers it like a lid on a soap dish. The valves are often covered with a complex pattern, so under the microscope, many diatoms resemble fine jewelry. Depending on how their shell looks from the side of the valves, these algae are divided into two groups - centric and pinnate. The former have radial symmetry, while the latter have oblong cells and bilateral symmetry (sometimes they are somewhat asymmetric). The photomicrograph shows centric diatoms.
Flagella. These organisms, due to their ability to "animal" nutrition and a number of other important features, are now often referred to as the subkingdom of protozoa (Protozoa) of the protist kingdom, but they can also be considered as a department (type) not included in the Protozoa. Euglenophyta the same kingdom. All flagella are unicellular and motile. Cells are green, red or colorless. Some species are capable of photosynthesis, while others (saprophytes) absorb dissolved organic matter or even swallow its solid particles. Sexual reproduction is known only in some species. A common pond dweller is Euglena, a green algae with a red eye. She swims with the help of a single flagellum, is capable of both photosynthesis and nutrition of ready-made organic matter. Euglena sanguinea can turn pond water red in late summer.
Dinoflagellates. These single-celled flagellar organisms are also often referred to as protozoa, but they can also be distinguished as an independent department (type) Pyrrophyta of the protist kingdom. They are mostly yellow-brown, but they can also be 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 only in a few species. The marine genus Gonyaulax is one of the causes of the "red tides": near the coasts, it is so abundant that the water takes on an unusual color. This algae releases toxic substances, sometimes leading to the death of fish and shellfish. Some dinoflagellates cause water phosphorescence in tropical seas.
golden algae are included along with others in the department (type) Chrysophyta protist kingdoms. Their color is yellow-brown, and the cells are mobile (flagellated) or motionless. Reproduction is asexual with the formation of silica-impregnated cysts.
yellow green algae now it is customary to combine with golden ones into the division (type) Chrysophyta, but they can also be considered an independent division (type) Xanthophyta of the protist kingdom. In form, they are similar 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 only in a few forms.
Charovye(rays) - multicellular algae that make up the department (type) Charophyta protist kingdoms. Their color varies from grayish green to gray. Cell walls are often encrusted with calcium carbonate, so the dead remains of chars are involved in the formation of marl deposits. These algae have a cylindrical, stem-like main axis, from which lateral processes extend in whorls, similar to plant leaves. Characeae grow vertically in shallow water, reaching a height of 2.5-10 cm. Sexual reproduction. Characeae 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.
Inferior group aquatic plants, usually containing chlorophyll and producing organic substances during photosynthesis. The body of the algae is thallus, which does not have true roots, stems and leaves, from fractions of a micron to 60 m. Non-cellular, unicellular ... Big Encyclopedic Dictionary
SEAWEED- (Algae), a common name in society for all water plants (including flowering plants), and in science only for certain groups of lower plants, namely those that contain chlorophyll and can therefore feed on their own for through the assimilation of CO2. ... ... Big Medical Encyclopedia
ALGAE, a large group of photosynthesising organisms, predominantly aquatic, belonging to the kingdom of PROTOCTISTS. They exist in salt and fresh water throughout the world and are the primary food source for shellfish, fish and other aquatic... ... Scientific and technical encyclopedic dictionary
Diverse group of eukaryotic, photosynthetic aquatic and soil organisms. Microbiological objects. are microscopic, predominantly unicellular forms. (
Hi all! It's time for a new post, the topic of which will be general characteristics algae. From what you read below you will learn their structure, how they reproduce and what are algae in general, what is it?
General characteristics of algae.
Algae are lower semi-aquatic or aquatic plants that live in oceans, lakes, streams and ponds, or on wet land. Together with animals, they form oceanic plankton and are the main food source for fish.
Some algae are huge and complex in structure, while others are unicellular organisms, which are not more than 0.01 mm in diameter. Some of the marine species of algae reach 100 m in length.
Algae are a rather diverse group of plants that are classified according to characteristics such as cell wall composition and pigmentation.
In total, there are about 20 thousand algae in the world. They find shelter for themselves in hot springs, in which water is boiling water, and in polar ice, willows in salty brine, and in hard water.
Structure.
All algae cells have chromatophores that contain various pigments. Green chlorophyll - the most important of these, it is present in chromatophores called chloroplasts. In different algae, the number and shape of chloroplasts are different.
For example, chlorella has a single chloroplast that looks like a cup. Spirogyra has numerous chloroplasts, which are connected in long spiral ribbons. And in other algae, they are in the form of stars or saucers.
Each group of algae has its own range of pigments in a special combination. Thanks to this, there are groups of blue-green, brown, red and green algae. Some of the species form lichens in symbiosis with.
unicellular algae like chlorella, they consist of only one cell, where inside the shell there is a carrier of genetic material - DNA (nucleus) - and chloroplasts containing chlorophyll.
Some unicellular algae can move with the help of flagella. Multicellular algae consist of many filaments that form thallus of different shapes, this is clearly seen in the example of seaweed.
Reproduction.
Algae reproduce in a variety of ways. Some reproduce vegetatively (fragments of thalli fall off and grow further on their own). unicellular algae usually multiply in the same way as some - by division.
Asexual reproduction of higher algae occurs with the help of spores, which are formed from the mother cell. Some spores have flagella (zoospores) that give them mobility.
Just like in bacteria conjugation also occurs. In a more intricate way, sexual reproduction occurs in more complex algae (like fucus). The female and male reproductive organs of most fucus species appear on different plants, but sometimes they are found on one.
The female (oogonia) and male (anteridia) reproductive organs, which appear in the spring, throw their cells into the water when they are covered by a tidal wave. With the help of flagella, male gametes approach and merge with immobile eggs.
At first, a fertilized egg is enveloped by a cell wall, and later germinates and gives rise to a new plant.
I hope that the general characteristics of algae helped you figure it out 😉
Than in any other vegetables? But that's not the most amazing thing about the incredible properties of algae.
What is edible algae and what are
Algae are living organisms that inhabit sea and fresh water. Some of them are single-celled, while others are very similar to land plants, although from a biological point of view, they are not. Algae represent the genus Algae. Scientists talk about the existence of more than 30 thousand varieties of these organisms. But not all of them are considered edible.
Those that fall on our tables can be divided into 3 groups: brown, red, green.
The most famous representatives of brown algae are kelp, hijiki, fucus, limu, wakame (or chuka). Laminaria is known to everyone. This seaweed is the absolute world champion in iodine content.
Red algae are porphyry, dals, rhodimenia, carrageenan. Porphyry is one of the most popular varieties edible algae. Well, who hasn't heard of nori, the seaweed traditionally used to make sushi? And nori is porphyry seaweed.
Green sea plants used as food product, this is the well-known spirulina, umi budo (aka sea grapes), ulva (also known as sea lettuce), monostroma (aonori). By the way, the uniqueness of spirulina is that it contains an incredible amount - at least 3 times more than meat.
Chemical composition
The chemical composition of edible algae of different types is slightly different. But in in general terms the set of useful elements in red, brown and green varieties is similar.
So, any algae can be considered as a source, and most of the substances from. Also, these aquatic "plants" contain a lot and, but most of all, as they said, iodine (each kilogram of algae contains within 1 g of iodine). In addition to it, there are many other components. By the way, vanadium, which reduces the level in the liver, is a component unique to food products. In addition to algae, it is also found only in bee products. It is also interesting that, in terms of the set of minerals, seaweed is very similar to chemical composition human blood.
In addition, these organisms are rich in phenolic compounds, vegetable, as well as lignins, and other biologically valuable components.
Porphyra (nori)
Porphyra is a very common algae. Lives in different seas, including Black, Baltic, Mediterranean, White. This representative of red water "plants" is useful for preventing atherosclerosis and lowering cholesterol levels. These properties of nori make them useful for people with work impairments. of cardio-vascular system. In addition, nori is known as a source of vitamins A, D and. Traditionally used in Japanese, Korean and Chinese cuisines.
lithotamnia
The extremely rich mineral and vitamin composition is the first thing that comes to mind when we are talking about the red coral alga lithotamnia. The researchers counted more than 30 minerals in this product, including incredibly high portions of magnesium and iron. Due to this, lithotamnia is considered one of the most useful products for the prevention and treatment of anemia.
anfeltia
This red inhabitant of the Black Sea, as well as the outer seas of the Far East and the North, resembles small spherical bushes. It usually grows near the coast at a depth not exceeding 5 m. It is anfeltia that is the basis for the production of a natural thickener known as agar-agar. This substance is used in marmalade, marshmallow and some other products.
In medicine, ahnfeltia is known as a natural cure for breast cancer. But abuse of the product can cause severe diarrhea.
Phyllophora ribbed
This is a red algae from the Black Sea, common in places where rivers flow into the sea. For many years served as a source of iodine. It is actively used in the beauty industry as an agent that effectively slows down aging.
Benefits for weight loss
In some types of algae, researchers have found an enzyme that is also contained in - the one that causes splitting. On the other hand, sea "plants" are also useful in that by consuming them in large quantities, you can get rid of hunger for a long time. This is because the algae, absorbing liquid, swell and create a feeling of fullness in the stomach. And all this against the background of a low calorie content, but rich in mineral and vitamin composition.
To speed up the breakdown of fats, it is useful to drink tea brewed from the collection of herbs and seaweed. For this, funds are taken in equal proportions. corn silk, dandelion, buckthorn, bearded cystoseira, bearberry, willowherb, licorice, alfalfa and algae (preferably kelp and fucus). Take 2 tablespoons of the collection per liter of boiling water, insist for at least an hour. You need to drink tea 5 times a day, 100-150 ml. The course of treatment should not last more than 2 months. Repeat after 30 days.
Possible dangers from consumption
Potential harm from algae is possible in case of an allergy to them. In addition, kelp, for example, is contraindicated in people with kidney disease, stomach ulcers, gastritis and tuberculosis patients. People with an overactive thyroid gland can use sea "plants" only with the permission of a doctor.
Applications
Algae belong to those products that a person uses in a variety of areas. The most obvious use is as food. In addition, in the food industry, kelp and fucus are raw materials for algin (, E400), which is used in the confectionery business as a thickener and stabilizer. E400 can usually be seen in some sweets, ice cream, yogurt, and even. Another representative of the E-components, obtained from red algae, is E406, also known as agar-agar thickener.
How to cook
It is best to eat fresh or dried seaweed. You can cook them in several ways: after soaking, add to ready-made dishes, steam or grind a dry product, mix with spices and add to food in this form.
Today, algae is an affordable product in supermarkets. In addition, presented in the most different forms: frozen, salted, marinated, dried, dried, in the form of ready-made salads. When buying dried seaweed, it is important to carefully check the tightness of the packaging. But the white coating on the product should not be frightening - this is a sign of properly harvested "plants". Before use, dried seaweed is poured with water for a while, after which it is added to salads, broths, snacks, rolls.
The inhabitants of Asian countries were the first to include algae in their diet. In oriental cuisine, this product takes pride of place. But sushi is far from the only dish in which sea "plants" look organic. This exotic is perfectly combined with mushrooms, beets, algae can be stewed in oil, and they also make a good snack for strong alcohol.
Use in cosmetology
In beauty salons, procedures using algae are one of the most popular, but also expensive pleasures. And all because they are effective. One of the most popular procedures is anti-cellulite body wraps using seaweed. Also, the extract of this product is added to creams, serums, including those for sensitive or problem skin. Algae is used in baths, hair products and face masks.
Bioactive substances contained in algae:
- normalize metabolic processes;
- rejuvenate aging skin;
- restore the structure of the skin;
- promote the production of collagen and elastin;
- make the skin elastic;
- moisturize the skin and hair;
- restore a healthy complexion;
- eliminate stretch marks.
These beneficial features aquatic "plants" are actively used in the beauty industry around the world.
Researchers say that algae have inhabited our planet for over 2 billion years. For several centuries, people have been eating them (although quite recently they did not even know what unique properties these organisms have). The benefits of algae seem to be impossible to overestimate. Nature endowed these amazing inhabitants of reservoirs with incredible properties. And, of course, those who call algae a super food are right. But still, one should not forget that excessive enthusiasm for even such useful product can sometimes be dangerous.
Algae, as they say name - plants living in water. However, this is not quite true. Algae are able to live and reproduce in conditions that at first glance seem completely unsuitable for habitation.
The structure of algae is very diverse. They can be unicellular, colonial, multicellular. Their sizes vary from a few microns to 30 meters. In total, there are about 30 thousand species of algae in nature. These are the most ancient plants of the Earth. They are found in deposits formed from three to one billion years ago. It is they who owe the earth's atmosphere the appearance of oxygen. For such a long period of development, algae have adapted to the most incredible conditions of existence. Most of them live in the seas, oceans, rivers, streams, swamps - wherever there is water. However, many species are also found on the surface of the soil, on rocks, in snow, hot springs, salt water bodies, where the salt concentration reaches 300 grams per liter of water, and even ... in the hair of sloths living in moist forests South America, and inside the hair of polar bears living in zoos. Polar bears have hollow hair inside, and Chlorella vulgaris settles there. With mass development, algae “color” animals in green color. However, the life of all these plants is associated with water, they can easily tolerate drying out, freezing, but as soon as a sufficient amount of moisture appears, the surface of objects becomes covered with a green coating.
There are species of algae that live as symbionts inside the body of some animals and plants. The well-known lichen is an example of a symbiosis of a fungus and an algae.
Terrestrial, or, as they are also called, air algae, can be found on tree trunks, rocks, rooftops, fences. These algae live wherever there is even the slightest constant moisture from rain, fog, spray from waterfalls, and dew. During dry periods, the algae dry out so much that they easily crumble. Growing in open areas, they warm up strongly in the sun during the day, cool at night, and freeze in winter. 
Despite seemingly unfavorable living conditions, air algae often develop in large numbers, forming bright green or red blooms on the surface of objects. On the bark of trees (most often on the north side), the most common settlers are green algae - pleurococcus, chlorella, chlorococcus, trentepolia. Pleurococcus forms green plaques on the lower part of tree trunks, stumps, fences, while trentepolia creates red-brown plaques on the entire trunk. Especially a lot of terrestrial algae in areas with a humid and warm climate. Scientists have discovered more than 200 species that can live in warm and hot water. Their predominant number refers to blue-green. Most species live in water bodies at a temperature of 35-40 degrees Celsius. As the temperature rises, their number sharply decreases.
On glaciers, snowfields, and ice, algae often also settle, but of other, cold-loving species. Under these conditions, they sometimes multiply so intensely that they paint the surface of ice and snow in a wide variety of colors - red, crimson, green, blue, blue, purple, brown and even ... black - depending on the predominance of certain cold-loving algae. 
In the spring, as soon as frosts subside, snow algae begin to multiply intensively. They are dark in color and therefore absorb more heat rays than the surrounding white surface, which contributes to faster melting of snow around the algae.
The higher up the mountains, the less diverse species composition algae. Gradually disappear diatoms, green, and the leading role passes to previously invisible in total mass blue-green. These algae are "snow leopards" among the conquerors of cold heights. At an altitude of about 5 thousand meters, they become the only inhabitants of the glaciers, forming the "border of life" in the highlands. Algae develop no less intensively in the ice of the Arctic and Antarctic basins. Diatoms are especially active. A huge amount of them mows the ice in brown and yellow-brown colors.
The “blooming” of ice, in contrast to the “blooming” of snow, occurs mainly due to the mass development of algae not on the surface of the ice, but on its lower parts immersed in sea water. Then, with the onset of winter, they freeze into ice. And as the summer thaws, frozen algae gradually come to the surface, where they die in puddles of desalinated water.
Algae also develop in lakes where the salinity is so high that the salt falls out of the saturated solution. Only a few algae tolerate very high salinity. However, they develop in huge numbers, coloring water and saline (it is also called "brine") in green, blue-green and red colors. For example, in Astrakhan region in the old days there were salt lakes in which the salt was pink, with the smell of violets or ripe raspberries. She was very much appreciated and served at the royal table.
Another common inhabitant of salt lakes is the blue-green algae chloroglea sarcinoid. Accumulations of huge colonies of these algae often break from their places, the wind and waves overtake them throughout the lake, then they are thrown ashore. Sometimes powerful layers of such algae are formed. The silt left after the death of chloroglea is involved in the formation of therapeutic mud.
A significant part of algae lives in the soil. Their greatest number is found on the surface of the soil and in its uppermost layer, where it penetrates sunlight. Here they live by photosynthesis. With depth, their numbers and species diversity decrease sharply. The greatest depth at which viable algae were found is 2 meters. Scientists believe that water or soil animals bring them there. Under such unfavorable conditions, algae are able to switch to feeding on dissolved organic substances.
In the earth, the life of algae is associated with water films that are present on the surface of soil particles. Algae crusts on the soil, which dry out during dry periods, begin to grow within a few hours after wetting. In some soil algae, an important protective device against drought is the abundant formation of mucus, which, even with little moisture, is able to quickly absorb and retain a large amount of water, 8-10 times the dry weight of algae. Thus, algae not only store water, preventing drying, but also quickly absorb it when moistened.
These algae are very viable. For example, many times, scientists managed to revive those that were stored in museums in a dry state for decades. They are able to withstand sudden temperature fluctuations. Many of them remained viable after being heated to 100 or cooled to 195 degrees. Soil algae are resistant to ultraviolet radiation and even ... radioactive radiation. With various devices against adverse conditions environment, they are the first to populate soil surfaces and take part in the soil-forming process, especially in its initial stage.
PhD in Biology
A. Sadchikov
