The main signs characteristic of algae. Features and significance of algae

What are the main signs characteristic of algae? How do they differ from other plants? What functions are performed? We will deal with this below.

What is algae?

Until the middle of the twentieth century, algae, together with fungi, lichens and bacteria, were referred to inferior plants. Now this concept has lost its relevance. The term "algae" is purely biological, not systematic. The characteristics of algae are ambiguous, since they can belong to different departments and categories.

The concept itself means not a specific species, but a group of organisms, which are united by a number of common features. They represent heterogeneous multicellular, unicellular and colonial organisms. The main signs characteristic of algae are absence of blood vessels, presence of chlorophyll in cells, habitation in the aquatic environment. More than one hundred thousand algae are known. Their sizes can range from one micrometer to 40 meters in length.

Numerous species and classes of algae combine in the departments of green, brown, golden, yellow-green, cryptophyte. Almost all of them belong to the subregion of Algae in the realm of the plant. Exceptions are blue-green algae. They are classified as cyanobacteria.

Main features

Characteristic for algae features - is the presence of photoautotrophic nutrition, that is, the implementation of photosynthesis, thanks to the presence of chlorophyll. They absorb the substances from the environment by the entire surface of the body.

The main features characteristic of algae are also the absence of a clear division of the body into organs. Their body does not have roots, stems, leaves, but differs in structure from different algae. It can look like thin threads, plates, ribbons, etc.

Algae can have a variety of colors. The green color of many species is determined by the presence of chlorophyll, red, yellowish and other colors indicate the presence of various pigments. They do not form flowers, reproduction in different species occurs with the help of spores, vegetatively or sexually.

Habitat

Initially, they have an aquatic lifestyle, but some species have adapted to life in soils, trees and even rocks. Algae of small size can be attached to other algae or live on the bottom of water bodies, being part of the benthos.

Some small species freely float in the upper layers of the water together with plankton. There are also parasitic species that are introduced into the shells of organisms. The largest sizes are brown algae. Growing up, they form whole forests under the water, providing shelter to fish and other animals.

As a rule, they live at depths, which still can penetrate the sunlight. The maximum depth is 200 meters, although most species do not fall below forty. On the surface, algae often grow in conditions of good humidity. They can appear even on a fence or a house. Entering with the fungi in symbiosis, some algae merged with them into one, forming a separate species of organisms - lichens.

Biological significance

Due to active photosynthesis, algae are the main producers of organic substances in water. Due to the circulation of carbon dioxide and oxygen, they are part of the global cycle of substances. People use them as biofuels, they use it to purify water.

Algae serve as food for many living beings. They are rich in iodine and minerals, so some species are consumed by people, for example, ulva, sea kale. They are used in pharmaceutics, as well as in the chemical industry, to produce agar-agar, cellulose, acetic acid, and alcohol.