Golden seaweed: species and names

Department Golden algae (photo, description and description of individual species you will find in this article) is known, perhaps, mostly only biologists. Nevertheless, its representatives play a very important role in nature. Golden algae - one of the ancient groups of algae. Their ancestors were primary amoeboid organisms. Golden algae resemble yellow-green, diatom and partially brown algae in a set of pigments, the presence of silicon in the shells of cells, the composition of the reserve substances. There is reason to believe that they are the ancestors of diatom algae. However, this assumption can not be considered completely proven.

Department of Golden algae: a general characteristic

The plants we are interested in have a significant morphological diversity. Golden algae (their photo is presented above) are both unicellular and multicellular, colonial. In addition, among the golden algae there is a very peculiar representative. Multi-nuclear thallus is a naked plasmodium. Thus, golden algae are very diverse.

The structure of the cells of these organisms is characterized by the presence of a different number of flagella. Their number depends on the species. Usually there are two, but it should be noted that in some species of golden algae there are three flagella. The third, motionless, is located between two moving ones. It is called a ganthone and is characterized by an extension at the end. The function of the gantoneme is that the cell is attached to the substrate with its help.

Coloring

Golden algae is a department that includes mostly microscopic species. Their chloroplasts, as a rule, are golden yellow in color. Of the pigments, mention should be made of chlorophyll A. In addition, chlorophyll E, as well as many carotenoids, including carotene and a number of xanthophylls, mainly golden fucoxanthin, was detected. Coloring representatives of the department of interest to us can have different shades, depending on the predominance of one or other of these pigments. It can be from greenish-brown and greenish-yellow to pure golden yellow.

Value and Reproduction

Golden algae, the species of which are numerous, are phototrophic organisms. Their significance lies, mainly, in the creation of primary products in reservoirs. In addition, they participate in the feeding chain of various hydrobionts, including fish, golden algae. Their types improve the gas regime of various water bodies, where they grow. They also form sapropel deposits.

The department of Golden algae is characterized by the multiplication of its representatives by simple cell division, and also by the decay of multicellular thallus or colonies into separate parts. Scientists also know the sexual process, which is a typical autogamy, hologamy or isogamy. As a result of the process of reproduction, endogenous siliceous cysts appear, differing on such a basis as the character of the sculpture of their shell. These cysts perform an important function - they help the algae survive adverse conditions.

Spread of golden algae

Algae are golden all over the world. However, most often they grow in temperate latitudes. These plants live mainly in fresh fresh water. Algae golden are especially characteristic of sphagnum marshes with acidic waters. A small number of these organisms live in saline lakes and seas. In polluted waters, they are much less common. As for soils, only single species of them live in them.

The Department of Golden Algae includes representatives of several classes. Below, we briefly describe some of them.

Class Chrysolops

Its representatives are distinguished by the presence of a complex thallus, which is represented by a mucous structure. Chrysocamps include colonial forms, immobile, passively floating or attached. The cells of these organisms have neither flagella nor superficial protrusions. They are united in a single whole by the general slime of the colonies, usually located in its peripheral layers, but may also be in the central part.

Class Chrysotrich

This class includes golden algae having a lamellar, filamentous and heterogeneous structure. All these organisms are multicellular, typically benthic, attached. Thallum is represented by branched or simple, single or multiple strings, discoid parenchymal platelets or bushes. They are not submerged in general mucus.

This class combines freshwater forms, less often marine and brackish water. Chrysotrich is the most highly organized group of organisms among all the golden algae. Its representatives are similar in appearance to ulotriksovymi, belonging to the department of Green algae, as well as heterotriks, belonging to the department of Yellow-green algae. Some representatives of chrysotrichs resemble some of the most simply arranged brown algae.

Class Chrysosphere

This class includes golden algae, whose body structure is coccoid. Cells of these organisms are covered with a cellulose membrane. Rigidity and rhizopodia in representatives of this class are completely absent. These plants are unicellular, immobile. Less common are colonial forms, which are clusters of cells that are loosely connected and not immersed in general mucus. They do not form plates or filaments during reproduction.

Class of Chrysophytes

This class combines golden algae, which have different types of organization of the thallus. It is his device that is the basis for the following orders in this class: rhizochrhizal (having a rhizopodial structure), chrysomonadal (moped forms), chrysocapsular (palmelloid forms), feotamnal (filamentous), and chrysospheric (coccoid forms). We suggest you get acquainted with the individual orders of this class.

Chrysomonadal (otherwise - chromulin)

This is the most extensive order, uniting golden algae, having a monadic structure, both colonial and unicellular. Systematics of chrysomonads is based on the structure and number of flagella. Of particular importance is the nature of their cell walls. There are single and double-gland forms. Previously it was believed that the more primitive, the original is the first. However, the electron microscope helped scientists to find out that the supposedly single-gland forms have a second side flagellum of small size. The researchers suggested that the initial ones could be two-flagellate chrysomonads that have heteromorphic and heterocellular flagella, and single-gland forms appeared as a result of the subsequent reduction of the short bundle.

As for the cellular coverings of representatives of chrysomonadal, they are different. There are bare forms, dressed solely by plasmalemma. Cells of other species are enclosed in special cellulose houses. Above the third plasmalemma there is a veil consisting of silicic scales.

With the help of cell division the process of reproduction of chrysomonads is carried out. In some species there is also a sexual process.

It should be noted that chrysomonads are basically freshwater organisms. Most often they live in clear waters. Chrysomonads are usually found in the cold season, late autumn and early spring. Some organisms live under the ice in winter. However, as scientists have found out, for them the temperature of water is not so important. It has only an indirect meaning. Water chemistry is a decisive factor. Throughout the year it changes: in the cold season in the water as a result of the lack of other vegetation contains more nitrogen and iron. Most chrysomonads live in plankton. They have special devices for plankton lifestyle. Individual members of the chrysomonad stain water in a brown color, causing it to bloom.

We suggest you get acquainted with the family Ohromonadovye, which belongs to this class.

Family Ohromoded

We continue to consider the department of Golden algae. Representatives of the family Okhromonadovye - various bare forms. Their cells are covered only by a cytoplasmic membrane, which has one or two flagella (unequal).

Rod Ochromonas

Algae of this genus usually live in the neuston or plankton of fresh water. Less often they are found in brackish water reservoirs. This genus is represented by single cells of golden color, having two heteromorphic and heterocomposite flagella. Ochromonas is a naked cell, which is clad only on the outside with a cytoplasmic membrane. The cytoskeleton, consisting of microtubules located peripherally, supports its drop-shaped form. In the center of such a cell there is a cell nucleus. It is surrounded by a nuclear envelope consisting of two membranes.

The plate chromatophores (two of them) are enclosed in the expansion that exists between the membranes of the nuclear envelope. Their ultrastructure is typical of the department to which they belong. A large vacuole together with chrysolaminarin is located in the back of this cell. The mitochondria are scattered in the cytoplasm, the Golgi apparatus is in the anterior part of such a cell. From its anterior end, flagella depart. There are two of them, they are not the same in length.

G. Buck studied the origin of the mastigonem and a subtle structure in Ochromonas danica (golden algae). The photos with the names help to visualize certain kinds of organisms. In the photo above - algae Ochromonas danica. This type is convenient for determining what the dynamics of development mastigoneem. The fact is that its cells have one interesting feature - they easily lose their flagella, after which they form anew. This allows you to examine the material at various stages of regeneration of their flagellar apparatus.

Family name Mallonamas

Its representatives usually live in freshwater plankton. This genus is the most rich in species. The cells of its representatives are different in form. They are covered with scales with bristles or silicified scales. Mallomonas caudata (pictured above) is one of the largest species among representatives of this genus. It describes in detail the ultrastructure of the contents of the bristles, scales and cell contents, as well as the mechanism of their formation, release and subsequent deposition on the cell surface. However, studies of this kind are still relatively few.

In brief, let's talk about the flagella of such a representative of the genus Mallomonas, as M. caudata. They have two, but one is only distinguishable in an optical microscope. This flagella has a normal structure. It carries 2 rows of hairy mastigonem. In the light microscope, the second flagellum is indistinguishable, which protrudes a short distance from the cell. The cover of the scales hides it.

Rod Sinur

This genus is characterized by ellipsoidal or spherical colonies consisting of pear-shaped cells. In the center of the colony they are connected by the back ends, sometimes very long. From the cytoplasmic membrane on the outside, the cells are clothed with silken scales. These scales are arranged spirally, they overlap each other cristately. The ultrastructure and shape of these scales, like the mallonamas, are of great taxonomic significance. For example, in a representative such as S. sphagnicola (pictured above), the basal plate examined on the transverse cut is flat, that is, it has the same thickness. Small perforations permeate it. The apical thickened edge is at the anterior margin. The basal margin is bent. He surrounds the basal plate, forming something like a staple in this golden alga. Its representatives have a hollow spine bent outward. It is attached at some distance from the front edge of the plate. It's time is at its base.

As for other representatives of such a department as Golden algae, the structure of their scales is somewhat more complicated. This applies, in particular, to S. petersonii. On top of the finely perforated basal plate, this species has a medial crest (hollow). It is apical, blunt or pointed. The end of it can extend beyond the frontal edge of the scales, thus imitating the spike. A large pore is located in the medial crest, in front of it. The basal end of this flake is bent horseshoe. He hangs over her body. The posterior and anterior scales that cover the body of the cell have transverse ribs that extend from the medial crest. In addition to the transverse, the median also has longitudinal ribs. On the cell, the scales lie not flat, but are attached, apparently, only to the opposite end. In S. sphagnicola (pictured above), body flake profiles may also be present in cytoplasmic vesicles, mainly located near the outer surface of the chloroplast, although they can also be observed between it and vesicles with chrysolaminarin.

The group of kok-colitoforid

Golden algae, the species and names of which we study, are numerous. Among them is a special group - kok-colitoforid. Its representatives have their own characteristics. The pellicle is surrounded from the outside by an additional layer of coccoliths (the so-called round calcareous bodies). They are in the mucus that protoplast secrete.

Class Haptophytes

This class is distinguished primarily in the structure of monadic cells that possess a haptonemia, in addition to flagella. The composition of this class includes three orders. Consider one of them.

The order of the primitive

It is usually characterized by two isomorphic and isocontained flagella, as well as a long gaptoneum. Outside the plasmalemma, the surface of the cells is covered by unmineralized organic scales or coccolith bodies (calcareous), which together form a coccosphere around the cell.

One of the families of this order is Prymnesiaceae. As in the fresh waters, and in the seas, the genus of Chrysochromulin is represented. Oval or spherical cells with two smooth flagella of equal length, as well as the haptoneum are covered externally from the cytoplasmic membrane by unmineralized organic scales. The latter are usually of two types. They differ either in shape or in size.

For example, Chrysochromulina birgeri has two types of scales that cover its body. They differ only in size. These scales consist of oval plates, the pattern of which is represented by radial ridges. There are also two central protrusions, represented in the form of horns. The cell surface in other species is covered with scales, which morphologically differ more or less sharply. For example, flat, round internal scales in Ch. Cyanophora have thin concentric crests. They overlap each other, forming a case around the cage. Usually they are hidden by numerous cylindrical scales located on the outside.

Two kinds of scales are also found in Ch. Megacyiindra are cylinders and plates. Cylinders are distributed fairly evenly throughout the cell. Each of them is attached to its basal plate by its lower end. The sides of these cylinders almost touch each other. Below them, there are flat scales with rims forming many layers.

Three types of scales are observed in Ch. Chiton. Their arrangement is characteristic: six large ones without a rim are located around one, large and with a rim. The spaces between them are filled with the smallest flakes.

In conclusion, we briefly consider another family.

Family Kokkolitoforidovye

It is mainly marine species. The exception is the hymenomonas - a freshwater genus. Monadic cells of representatives of this family have two identical flagella. Haptonemia in them is usually noticeable well enough. Nevertheless, in a number of coccolithophorids, it appears to be reduced. For example, it is not observed in N. coronate.

Cells of representatives of this family do not differ in structure from those of other haptophytes. They have a nucleus, as well as chloroplasts, which are surrounded by an endoplasmic reticulum. They contain tritylakoidnye lamellae, with no surrounding lamellae. In the cell there is a pyrenoid. Paired thylakoids cross it. Also there are mitochondria, the Golgi apparatus , etc. As for the cell cover, it is located outside the cytoplasmic membrane. Kokkolity - scales, impregnated with carbonate, of which it consists. Kokkolity together form a coccosphere around the cell. Some forms have organic non-mineralized scales besides them.

Kokkolity and writing chalk

The origin of the writing chalk, familiar to all of us, is very interesting. When examined under a microscope, if you do not greatly enlarge the image, investigators usually catch sight of foraminifera shells. However, with a stronger increase, a number of transparent plates with a different origin are found. Their value does not exceed 10 μm. It is these plates that are the coccoliths, which are particles of the shell of algae coccolithophoride. Using an electron microscope allowed scientists to establish that the coccolites and their fragments account for 95% of the chalk. These interesting formations are currently studied from the point of view of the ultrastructure. In addition, scientists examined their genesis.

So, we briefly reviewed the department of Golden algae. The classes and individual representatives of him were characterized by us. Of course, we only talked about some species, but this is enough to make a general idea of the department that interests us. Now you can also answer the question: "Algae is golden - what is it?"