Euglenoid algae are tiny unicellular lower organisms with a body shape resembling a spindle or oval. In view of the fact that they stand on the border of the plant and animal world, they were given the name of the frontiers. The thallus is represented mainly by the monadic, i.e. flagellated, palmelloid and amoebic forms are much less common. The color of algae is not very diverse, they are green, colorless and in rare cases red.
Distribution
Euglenic algae are found throughout the earth. They are present in any fresh body of water with stagnant water. However, they are practically absent in the seas and oceans. In flowing reservoirs, as well as in the plankton of the central part of large ones, there is a small amount of them.
The most favorite place is shallow fresh stagnant water bodies, at the same time well warmed up and enriched with organic matter, located in the forest-steppe and forest zone:
- ponds;
- forest puddles;
- ditch.
In the summer, you can often see the following picture - water turns green in a puddle or pond, or they also say “blooms”. The reason for this phenomenon is the massive development of algae. In a drop of such water, under a microscope, you can see spindle-shaped cells of a green color. By changing shape and bending, they move quite quickly in different directions. They are called euglena - this is the central genus. The whole department has the same name.
General information
The Euglena algae department has more than 900 species and 40 genera. Among them there are both saprophytes and parasites. And also one class Euglenophycia, which combines several orders that differ in some details of the structure of the flagellar apparatus. All of them are flagellated unicellular organisms that live in fresh water. Movement is carried out as a result of metabolic changes in the shape of the body and with the help of the flagellum. Chloroplasts contain chlorophyll and other pigments. By a simple longitudinal, into two parts, splitting of the cell, both in a mobile and in a stationary state, reproduction occurs. These algae have several types of food:
- consumption of dead organic substrates is saprotrophic;
- swallowing organic matter - holozoic;
- photosynthesis is autotrophic;
- mixotrophic, i.e. mixed.
Euglena, trachelomonas belong to the representatives of euglena algae.
Euglena
Amongrepresentatives of the order Euglenae distinguish the genus Euglena. These are mobile cells having a ribbon-like, spindle-shaped, cylindrical, ovoid or spirally twisted shape. In this case, one edge (front) is smoothed, and the other (back) is pointed. The cell is covered with a soft shell - the pellicle. A distinctive feature is the presence of an external flagellum, with which it moves. It is located at the anterior end of the cell in the flagellar pocket (pharynx) to which the red eye (stigma) is attached.
At the base of the flagellum there are contractile vacuoles, they eject the contents into the pharynx. The organism of the algae is capable of performing functions such as respiration, digestion and excretion. Despite the fact that all euglens contain chlorophyll, they have a mixed type of nutrition. Reproduction is asexual by binary longitudinal fission. Algae is able to transform into a cyst under adverse conditions. Some species change their body shape. There are quite a lot of them in nature, they provoke the "bloom" of water, giving it a red tint. This color is associated with the presence of a significant amount of carotene pigment in the cells.
Fakus
This is a genus of unicellular algae, of which about one hundred and forty species are known. The cells have a flattened body, ending at the posterior end with a curved narrow or straight process. The colorless shell is dense, it has rows of spines and granules. Pigment carriers (chromatophores) are small, numerous, parietal, discoid, without cell organelles. In the backpart of the cell is the nucleus.
Algae is common in the coastal parts of lakes, rivers, as well as small stagnant water bodies that are polluted with organic substances.
Trachelomonas
This genus includes about two hundred species of organisms that swim freely and own a flagellum and a solid house. The structure of the latter is considered a characteristic feature of the species. A different-shaped house is usually brown in color. Its walls are with granules, spikes, papillae. The back end is rounded or tapered.
Two or more pigments present. There are species without chlorophyll, i.e. colorless. The cell divides during reproduction inside the house. One individual goes outside through the existing hole and creates its own house.
Structure of eugleno algae
These are unicellular, vigorously moving organisms with one or two flagella. The body shape is oval, elongated or spindle-shaped. Outside, the cell is covered by the so-called pellicle, consisting of a cytoplasmic membrane. If it is soft and elastic, then these types of algae are able to change the shape of the body. Others have a hard shell, impregnated with iron s alts.
The green color of eugleno algae is provided by chlorophyll, which is also present in higher plants. In addition to this pigment, algae have xanthophylls and carotenes located in chloroplasts. The main reserve substance is the reserve polysaccharide paramylum, which performs an energy function. At the front enda depression is observed, it is considered the output end for the system of contractile vacuoles. In the latter, as a result of metabolic processes, liquid with dissolved substances accumulates.
Features
Brief description of euglena algae:
- Body shape - oval, fusiform, needle-shaped. The anterior end is rounded, the posterior end is elongated and pointed.
- Flagellar apparatus - from one to seven visible flagella. There are also several forms in which it is absent. Most often found with two flagella of different lengths.
- Light-sensitive apparatus - paraflagellar body (flagellar thickening) and ocellus.
- One big core.
- Contractile vacuole - located at the front end of the cell.
- Mitochondria - can merge and form a network. Euglenoids living under anaerobic conditions do not have them.
- The cell wall is a pellicle that is 80 percent protein. In addition, it contains carbohydrates and lipids.
- Chloroplast - different species have their own shape: discoid, stellate, lamellar, etc. There are several chloroplasts in the cell.
- Reserve product - paramylon.
- Biosynthesis of lysine - carried out as in real animals and fungi.
- Life cycle - reproduce by cell division into two parts.
Meaning and ecology
The practical importance of euglena algae is associated with physiological properties. By feeding on organic matter, theyactively participate in the self-purification of water bodies that are polluted with living substances. Among these algae, there are several species that are excellent indicators of the degree of pollution of the reservoir. They are able to form on their surface unstable films of multi-colored colors - red-brick, green, brown, yellow-green.
Due to the fact that algae have different ways of feeding, they are actively used as models in medicine, cytology, biochemistry, and physiology. Among them there are parasites that live in the intestines of amphibians, nematodes, on the gills of fish, oligochaetes.
