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Definition of Euglenophyta
Have you seen plankton? One of the constituents of plankton is the Euglenophyta group, has a single cell (unicellular), and has a true nucleus. Euglenophyta or Euglenoid comes from the Greek, namely eu which means true and gleen which means eye. Named Euglenophyta because organisms belonging to this group have red eye spots (stigma) that can catch light ( photoreceptive eyespot ) and chloroplasts.
Most of the Euglenoids are autotrophs because they can photosynthesize, some are heterotrophs. The most prominent feature of these protists is their unicellular (single-celled) body, bright green in color and very beautiful. The shape of the euglenoid cell is oval with a more slender posterior part. Although Euglenoids are grouped in the group of plant-like Protists, these living things do not have cell walls like plants. In the absence of a cell wall, they are free to move, so they are often mistaken for animal cells.
Euglenophyta is a unique group of protists because it has properties similar to plants and animals. Considered similar to plants because it has chlorophyll a and b, carotenoids are also found so that he will photosynthesize. Euglenophyta are considered animal-like because they can move actively with the help of one or more whip hairs (flagellates) that come out of their cells. Because it has a locomotion, it can live in waters, such as fresh water and stagnant water.
The results of photosynthesis in Euglenophyta are stored as food reserves in the form of paramylon polysaccharides . Euglenophyta live as photoautotroph organisms through photosynthesis. However, if the conditions are less favorable, for example there is no sunlight, then Euglenophyta can also live as heterotrophs, by eating the remains of organic matter. Euglenophyta have habitats in fresh water, such as pond water, rice fields, lakes, and are often found in farm ditches which contain a lot of animal waste.
Euglenophyta Body Structure
To date, around 1,000 species of Euglenophyta have been identified. One well-known species is Euglena viridis . Using a light microscope, Euglena viridis appears green. Chlorophyll is stored in oval shaped chloroplasts. Euglena is a distinctive member of this group, numbering about 400 species.
Euglena cells are elongated oval in shape, not rigid, do not have a cell wall containing cellulose, but have a supporting layer of cell membranes and proteins in the form of a flexible pellicle (flexible ) . Thus, he can change shape easily. At one end there is a mouth of the cell and from the mouth of the cell grows several flagella with different sizes. Long flagella are used for locomotion and other flagella are short. Euglenophyta show phototaxis motion, which is the movement of moving places towards the sun.
There is also an eye spot called the stigma. Stigma contains photoreceptors that are covered by red pigment and function to distinguish light and dark. Euglena also has an anterior esophagus, although it is not used for swallowing particulate food. Inside the cell there is also a contractile vacuole whose function is the same as Protozoa.
How does Euglena get her food? These organisms carry out photosynthesis in chloroplasts and are facultative autotrophic. Most of these organisms are able to assimilate organic substances during photosynthesis. In fact, some types of Euglena can swallow food in the form of particles through temporary openings adjacent to the esophagus.
Euglenophyta Characteristics
Euglenophyta or Euglenoids have general characteristics or characteristics, which are as follows.
■ Unicellular (single-celled)
■ From the mouth appear one to four flagella (whip feathers) which serves as a means of motion.
■ In general, have flagella of unequal length (Heterokontae)
■ Characteristically motile (likely to move).
■ colored green because they contain chlorophyll.
■ Cells elongated oval.
■ At one end there is the mouth of the cell.
■ Generally live in fresh water rich in organic matter.
■ Autotrophs and or heterotrophic. It is autotrophic, because it has chlorophyll a and b, beta carotene and some xanthophylls. Heterotrophs because they eat organic particles (ex. bacteria ) that are available. Some types of Euglena which are autotrophs can become heterotrophs when light levels are low.
■ Some have chloroplasts (for photosynthesis) and some are not.
They are phototrophic (make their own food), osmotrophic (eat by diffusion), and phagotrophic (eat by capturing food).
■ Backup paramilum food form, that is another form of polysaccharides.
■ Do not have a cell wall made of cellulose but have thin cell membranes are composed of layers of spiral-shaped proteins.
■ Have eye spots called stigma. Stigma ( eyespot ) is bright red that is sensitive to light. The red color on this stigma is the pigment astaxanthin. These eye spots serve to protect the light detectors located near the base of the flagella. With the detector, Euglena can move towards the direction of light of the appropriate intensity.
■ The body is covered pellicle.
■ Have a contractile vacuole and the food vacuole.
■ The anterior end of the cell in the form and in the form of lower sitostom esophagus.
Euglenophyta Classification
Phylum Euglenophyta is divided into three orders, namely:
1. Euglenales
2. Paranemales/Eutreptiales
3. Rhadbdomonadales
Euglenophyta Reproduction Method
How also do Euglenophyta (ex. Euglena) reproduce? Basically the way Euglena reproduces is the same as Protozoa, namely asexually. In general, this group reproduces asexually by longitudinal binary fission. At first it divides according to the longitude axis. The cells have 2 whip feathers and goblet-shaped chloroplasts and contain pyrenoids.
Before splitting, the pyrenoids extend across and the two whip feathers are far apart from each other. The pyrenoids and chloroplasts then make indentations and the cells will divide into two new individuals, each with a whip feather accompanied by the formation of a stigma.
Biologists have observed that Euglenoid reproduction occurs by mitosis, but they have not found sexual reproduction. Euglenoids often divide rapidly, so that chloroplast division has not yet had time to occur. This causes a new individual whose division results do not have chloroplasts and lose their color.
This new individual then grows into a living being that is heterotroph. The nature of the euglenoid, which is sometimes plant-like and sometimes animal-like, causes the grouping of Euglenoids to be a matter of debate.
Examples and Roles of Euglenophyta in Life
An example of a species of Euglenophyta is Euglena (green). Euglena includes all members of the Euglenophyceae whose cells during their lifetime have falgel and can move (motile). Solitary life, never forming a colony. Chloroplasts are disc-shaped and some are ribbon-shaped. Euglena's diet is very varied and includes all living organisms.
If Euglena grows in a dark place with a suitable organic substrate, the color will be lost so that it will be heterotrophic. However, if there is light, then Euglena will be colored again. Euglena's food reserves are in the form of paramylum, which is carbohydrates in the form of ring, rod or round discs, sometimes relatively large in size.
The role of Euglenophyta in life, among others, is as follows.
■ Used as an indicator of water pollution. For example, the surface of the water in which there is a lot of Euglena viridis , will appear greenish in color. While there is a lot of Euglena sanguinea looks reddish.
■ In the field of fisheries, Euglenophyta is phytoplankton that serves as a food fish.
■ In the economic field waters, Euglenophyta the primary producers in aquatic ecosystems, namely as a provider of organic matter and oxygen for aquatic animals such as fish, shrimp and aquatic insects.
■ In the field of science, Euglena is often used as an object of study observation. Because this type of algae is easy to get and breed and as an organic digestive.
■ In addition to the benefits of unisex loss (negative impact) that ditumbulkan by Euglenophyta, which pollute water sources and leads to accumulation of soil sediment at the bottom of a pond or lake.
