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Definition of Chrysophyta (Golden Algae)
Chrysophyta algae are also called golden algae ( golden algae ) or blonde algae. The term "Chrysophyta" comes from the Greek, chrysos which means "golden". The golden color is due to the presence of pigments in the form of carotenes and xanthophylls which are dominant compared to chlorophyll la and c, thus making the plastid cells yellowish green/golden brown. Other sources say that the golden color is caused by a pigment called fucoxanthin ( fucoxanthin ).
Chrysophyta mostly live in fresh water, although some species exist in sea water. Algae of this group have food stored as laminarin, which is a polysaccharide as food storage in these algae. Golden algae have a variety of structures and shapes. Some do not have cell walls and can crawl like Amoeba . Some have cell walls made of cellulose.
Most groups of golden algae are unicellular but some form colonies. Blond algae cells have two flagella, so they are called biflagellates, especially for algae whose cell wall structure is composed of pectin. The two flagella are attached near one end of the cell. In addition to living in water, there are also Chrysophyta that live on land.
Blond algae that live on land are often found as velvety membranes at the edges of ponds, waterfronts, or in moist soil. In addition to laminarin, Chrysophyta store excess food in the form of oil so that it is an important component in the formation of petroleum. Phylum Chrysophyta consists of about 5,300 species, and 5,000 of them are diatoms which are now included in a separate phylum, Bacillariophyta.
Characteristics of Chrysophyta (Golden Algae)
Golden algae (Chrysophyta) have the following characteristics or general characteristics.
■ Core are eukaryotic cells because the cell nucleus already had membranes.
■ There are unicellular (single-celled) and those that are multicellular (multicellular). The unicellular algae in the waters act as a component of phytoplankton.
■ Characteristically autotorof, because chlorophyll to perform photosynthesis. However, some are heterotrophs by absorbing food.
■ Habitat in waters such as freshwater, brackish water and seawater, and there is also a land of life, especially in places that are wet.
■ Anyone have a cell wall and there is not.
■ The cell walls contain cellulose, pectin or silica.
■ Most Chrysophyta have flagella to move mainly have a cell wall. But there are also amoeboid (moving crawling like Amoeba ) for Chrysophyta that do not have cell walls.
■ Have a pigment carotene, xantofil, chlorophyll a and chlorophyll c.
■ Most are microscopic (can not be observed with the naked eye).
■ Live solitary or in colonies.
■ Keep a spare makana in the form of laminarin or oil.
Classification of Chrysophyta (Golden Algae)
Golden algae are classified into three classes, namely:
■ Xanthophyceae (yellow-green algae). Has chlorophyll, xanthophyll. Example: Vaucheria sp .
■ Chrysophyceae (golden-brown algae). Has chlorophyll and carotene. Example: Ochromonas, Synura .
■ Bacillariophyceae (diatoms). Often found on the surface of wet soil (rice fields, sewers, ditches). Unicellular body, some are colonies. The cell wall is composed of two parts, namely the box (hypotheca) and the lid (epiteka). Example: Navicula , Pinnularia . But now diatoms have been separated from Phylum Chrysophyta and included in a separate phylum, namely Bacillariophyta.
Based on the type of cell, Chrysophyta can be divided into two types, namely:
Unicellular Chrysophya (Single-Celled)
■ Ochromonas , is a type of unicellular Chrysophyta having two flagella, one long and one short. Ochromonas can grow autotrophs by using sunlight energy or heterotrophs by absorbing food.
■ Navicula , often referred to as diatomaceous or algae grit, boxes or elliptical in shape, if the dead fossils will form diatomaceous earth that serves as an abrasive, mix cement or absorbent nitroglycerine on explosives. Reproduction divides itself by separating the body parts which consist of the hypotheca (box) and the epiteka (lid).
■ Pinnularia , like diatomaceous.
Chrysophya Multicellular (Multi-Celled)
■ Vaucheria , live in colonies in the tubular filament that sometimes branched. Types that live on land attached to the surface with rhizoids, namely branches resembling roots that are colorless. Vaucheria filaments are multinucleated and are not bounded by septal walls called senocytes. In the cytoplasm there is a large vacuole in the center of the cell. In the cytoplasm there are many nuclei, disc-shaped plastids without pyrenoids. Food reserves in the form of oil in the form of oil drops.
How to Reproduce Chrysophyta (Golden Algae)
How do golden algae reproduce? This golden algae can reproduce asexually (vegetatively) and also sexually (generatively). The following is an explanation of the two types of reproduction.
Reproduction Asexually (Vegetatively)
Asexual reproduction is carried out by the formation of large multinucleated zoospores that have many flagella as in Vaucheria . These zoospores are considered as a compound structure consisting of a collection of small zoospores with two flagella, each of which does not separate. After these zoospores are released, they then move with their flagella to a new place. Once settled, the flagella are released and germinate to form new Vaucheria . In addition to the formation of zoospores, there are also Chrysphyta species which reproduce asexually by dividing as in Ochromonas .
Sexual Reproduction (Generative)
Sexual reproduction in Chrysophytes is by oogamy , namely by forming oogonia (forming female gametes) and antheridia (forming male gametes) on the same filament. The resulting egg cell is large with one nucleus containing chlorophyll. Sperm produced by antheridia have small flagella. After fertilization occurs, a zygote is formed. Once released from the parent, the zygote is ready to grow to form a new filament.
Examples and Roles of Chrysophyta (Golden Algae) in Life
In human life, golden algae have many benefits, especially Navicula and Vaucheria . Navicula that has died and settles on the seabed forms soil deposits that are useful as abrasives, dynamite insulators, materials for making paints, varnishes, basic materials for the glass industry, filters and vinyl records. In Vaucheria , food reserves are stored in the form of oil, so this organism is a major component in the formation of petroleum.
