How beautiful and amazing the underwater world is, it is just as mysterious. Until now, scientists have discovered some completely new, unusual species of animals, studied the incredible properties of plants, and expanded their application.
The flora of the oceans, seas, rivers, lakes and swamps is not as diverse as the land, but it is also unique and beautiful. We will try to figure out what these amazing underwater plants are, what is the structure of algae and their significance in human life and other living beings.
Systematic position in the system of the organic world
By common standards, algae are considered a group of lower plants. They are part of the empire Cell kingdoms Plants and kingdoms Lower plants. In fact, such a division is based precisely on the structural features of these representatives.
They got their name because they are able to grow and live under water. The Latin name is Algae. Hence the name of the science involved in a detailed study of these organisms, their economic value and structure, is formed - algology.
Algae classification
Modern data allow us to attribute all available information about different types of representatives to ten departments. The separation is based on the structure and activity of algae.
- Blue-green unicellular, or cyanobacteria. Representatives: cyanide, shotgun, microcystis and others.
- Diatoms. These include pinnularia, navicula, pleurosigma, melosir, homfonem, sinedra and others.
- Golden Representatives: chrysodendron, chromulin, primesium and others.
- Porphyry. These include porphyry.
- Brown. Laminaria, sargassum, cystoseira and others.
- Yellow green. This includes classes such as Xanthopods, Xanthococcus, Xanthomonads.
- Reds. Gracillaria, anfelium, scarlet.
- Greens. Chlamydomonas, volvox, chlorella and others.
- Evshenovye. These include the most primitive representatives of the greens.
- Harovye. Hara as the main representative.
This classification does not reflect the structure of algae, but only shows their ability to photosynthesize at different depths, exhibiting pigmentation of one color or another. That is, the color of the plant is the sign by which it is attributed to one or another department.
Algae: structural features
Their main distinguishing feature is that the body is not differentiated into parts. That is, algae do not, like higher plants, have a clear separation into the shoot, consisting of a stem, leaves and flower, and the root system. The body structure of algae is represented by the thallus, or thallus.
In addition, the root system is also absent. Instead, there are special translucent thin filamentous processes called rhizoids. They perform the function of attaching to the substrate, acting at the same time as a sucker.
The thallus itself can be of very diverse shapes and colors. Sometimes in some representatives it strongly resembles the shoot of higher plants. Thus, the structure of algae is very specific for each department, therefore, it will be further considered in more detail using examples of the corresponding representatives.
Types of thalli
The thallus is the main distinguishing feature of any multicellular algae. The structural features of this body are that thallus can be of various types.
- Amoeboid.
- Monad.
- Capsal.
- Coccoid.
- Filamentous, or trichalous.
- Sarcinoid.
- False tissue.
- Siphon.
- Pseudoparenchymal.
The first three are most characteristic for colonial and unicellular forms, the rest for more advanced, multicellular, complex organization.
This classification is only approximate, since each type has transitional options, and then it is almost impossible to distinguish one from the other. The line of differentiation is erased.
Algae cell, its structure
The peculiarity of these plants is initially in the structure of their cells. It is somewhat different from that of the higher representatives. There are several key points by which cells are secreted.
- In some individuals, they contain specialized structures of animal origin - organelles of movement (flagella).
- Sometimes stigma occurs.
- The shells are not quite the same as in a normal plant cell. Often they are provided with additional carbohydrate or lipid layers.
- Pigments are enclosed in a specialized organ - the chromatophore.
In the rest, the structure of the algae cell is subject to the general rules of such in higher plants. They also have:
- core and chromatin;
- chloroplasts, chromoplasts and other pigment-containing structures;
- vacuoles with cell juice;
- cell wall;
- mitochondria, lysosomes, ribosomes;
- Golgi apparatus, endoplasmic reticulum and other elements.
Moreover, the cell structure of unicellular algae corresponds to that of prokaryotic creatures. That is, the nucleus, chloroplasts, mitochondria and some other structures are also absent.
The cellular structure of multicellular algae is fully consistent with that of higher terrestrial plants, with the exception of some species features.
Division Green algae: structure
The following types are included in this department:
- unicellular;
- multicellular;
- colonial.
In total, there are more than thirteen thousand species. Main classes:
- Volvox.
- Conjugates.
- Ulotrix.
- Siphon.
- Protococcal.
The structural features of unicellular organisms consist in the fact that on the outside the cell is often covered with an additional membrane that performs the function of a kind of skeleton - a pellicle. This allows her to be protected from external influences, to keep a certain shape, and also to form beautiful and amazing patterns of metal ions and salts on the surface over time.
As a rule, the structure of green algae of a unicellular type necessarily includes some organoid of movement, most often a flagellum at the posterior end of the body. A backup nutrient is starch, oil, or flour. Key representatives: chlorella, chlamydomonas, volvox, chlorococcus, protococcus.
Very interesting are such representatives of the siphon as Cowlerpa, Codium, Acetobularia. Their thallus is not a filamentous or lamellar type, but one giant cell that performs all the basic functions of life.
Multicellular can have a lamellar structure or filamentous. If we are talking about lamellar forms, then often they are multilayer, and not just single-layer. Often the structure of algae of this kind is very similar to the shoots of higher land plants. The more tall branches, the stronger the similarity.
The main representatives are the following classes:
- Ulotrix - ulotrix, ulva, monostroma.
- Selyanki, or conjugates - zygoneme, spirogyra, muzhotsiya.
Colonial forms are special. The structure of green algae of this type consists in the close interaction between a large accumulation of unicellular representatives, usually united by mucus in the external environment. The main representatives can be considered Volvox, protococcal.
Features of life
The main habitats are fresh water bodies and seas, oceans. Often cause the so-called flowering of water, covering itself with its entire surface. Chlorella is widely used in cattle breeding, as it purifies and enriches water with oxygen, and the dry residue goes to feed livestock.
Unicellular green algae can be used in spacecraft to produce oxygen as a result of photosynthesis without changing their structure and death. According to the time period, this particular department is the oldest in the history of underwater plants.
Department of Red Algae
Another name for the department is Bagryanka. It appeared due to the special color of representatives of this group of plants. It's all about pigments. The structure of red algae as a whole satisfies all the basic structural features of lower plants. They can also be unicellular and multicellular; they have various types of tall. There are both large and extremely small representatives.
However, their color is due to some features - along with chlorophyll, these algae have a number of other pigments:
They mask the main green pigment, so the color of plants can vary from yellow to bright red and crimson. This is due to the absorption of almost all wavelengths of visible light. The main representatives: anfeltsia, phyllophora, gracillaria, porphyry and others.
Meaning and lifestyle
They can live in fresh waters, but most are still marine representatives. The structure of red algae, and specifically the ability to produce a special substance agar-agar, allows its wide use in everyday life. This is especially true of the food confectionery industry. Also, a significant portion of individuals is used in medicine and is directly used by humans for food.
Division Brown algae: structure
Often, in the framework of the school curriculum for studying lower plants and their various departments, the teacher asks students: "List the structural features of brown algae." The answer will be this: the thallus has the most complex structure of all known individuals of lower plants, inside the thallus, which is often of impressive size, conductive vessels are located; the thallus itself has a multilayer structure, which is why it resembles the tissue type of the device of higher land plants.
The cells of the representatives of these algae produce special mucus, therefore, the outside is always covered with a kind of layer. Spare nutrients are:
- carbohydrate laminarite;
- oils (fats of various types);
- alcohol mannitol.
Here's what you need to say if you are asked: "List the structural features of brown algae." There are actually a lot of them, and they are unique against the background of other representatives of underwater plants.
Farm Use and Distribution
Brown algae is the main source of organic compounds not only for marine herbivores, but also for people living in the coastal zone. Their use in food is widespread among different peoples of the world. They make medicines, get flour and minerals, alginic acids.