In sea and fresh water, as well as on moist soil, diatoms grow. Brown color is given to these plants by yellow-brown photosynthetic pigments. The peculiarity of these algae lies in the fact that their cells are protected from the outside by a hard shell - Frustula (shell). Plants grow both individually and in colonies. They feed mainly on organic substances in the environment.
Diatoms have a unique structure. Their cells are composed of two cusps (epithecus and hypothec). Frustula walls are equipped with pores through which metabolism occurs with the external environment. Some plants with a slit-like opening along the carapace can move with the help of mucus along the substrate.
Algae multiply, like all living organisms, by division. Receiving part of the maternal carapace, the daughter cell begins to grow actively. However, at the same time, the old Frustula captures the new with its ends. Since the hard membranes of the cells are practically incapable of subsequent growth, algae noticeably become smaller during the reproduction process. However, due to the formation of auxospores, the contents of plant cells can exit the carapace and begin a new division. At the same time, the young generation of diatoms will be significantly larger than the previous one.
Types of algae:
- Melozira. This species lives both in sea water and in fresh water. Their nutrition is carried out through the process of photosynthesis. These diatoms are mainly used for biological analysis of water, which determines the degree of pollution of the reservoir.
- Homophonem. Plants of this species grow in clear waters. They attach to other algae or various objects located at the bottom and create their own colonies. This species is unpretentious to temperature conditions. For mollusks, these algae are valuable nutrient material.
- Pleurosigma. These plants live in brackish ponds, where they serve as food for young fish.
- Sanhedra. Diatoms of this group are unicellular plants. They create colonies reminiscent of their shape assembled into bundles of fans. As their "master" they choose green algae or plankton. The habitat of the Sanhedra is slow-flowing rivers and standing reservoirs. This species is unsuitable for feeding fish.
- Navikula. These algae can be found everywhere. They appear on the muddy bottom of fresh water bodies, on wet stones and soil cover.
- Pinnularia. Diatoms of this genus are found in muddy areas of water bodies and rice fields. Due to their high resistance to temperature changes, they live in almost every corner of the planet. The valves of plant cells are very well preserved in the silt. Due to this feature, the populations of pinnularia are highly viable.
Kelp algae grow in the Far East and the coast of the northern seas. Their length can be from 2 to 6 meters, and width - up to 35 centimeters. For its life, the plant chooses rocky soil. Depending on the climate conditions, the life expectancy of algae is from 2 to 4 years.
Laminaria propagates by spores, from which male and female growths are formed. They form gametes (germ cells). After fertilization, a young spawning kelp arises from the egg.
Algae is widely used in medicine, cooking and cosmetology.
Laminaria thalli are commonly used as food. From the plant, magnificent salads, soups, bread, sweets are obtained. In cosmetology, oils and algae extracts are used. The presence of an organic compound of iodine allows the use of kelp for medicinal purposes. The plant promotes protein assimilation, assimilation of calcium, phosphorus, iron, increases the tone of blood vessels.