In biology, two types of living organisms are considered colonial. First, these are those that consist of a large number of cells. However, these cells do not form organs - their functions are very differentiated. Also this group of organisms is distinguished by the fact that their cells do not form tissues. The next category are individual organisms that accumulate in the colony. Individuals in such colonies have a very similar genotype, in the colony there may be several. Biologists refer to this type of marine sponges, corals, algae.
To the colonial algae belong many of the department of green algae. This category is one of the most numerous in botany - it belongs to up to 20 thousand different species. The overwhelming number of species of green algae can live only in freshwater reservoirs. Although there are also marine species.
Green algae are represented by five classes. These include the so-called volvoksovye, protokokkovye, as well as ulotriksovye algae. The names of these classes come from the Latin language.
This type is very common in rivers and other flowing water bodies. Usually, its subjects are covered with objects under water. Tina consists of threads. At the beginning of the growth cycle, the filaments are attached to their base with a rhizoid - elongated cell. Ulotriks is a colonial alga, which multiplies in three ways: sexual, asexual, and also vegetative. This species lives in sea water, as well as in fresh water. The most common type of ulotriksa is the so-called ulotriks belted.
The second type of reproduction occurs with the help of zoospores ripening inside cells - oval cells, which have flagella at the anterior margin. Subspecies zoospores, after they leave the mother cell, are still near it for some time. Then they fall on the underwater object and settle on it. Sprouting, zoospores become an adult.
To the colonial algae also belong volvoksovye - algae, the body of which consists of active flagellated cells. This type comes from the most primitive forms - amoeba. Despite the fact that among volvoksovye there are colonial organisms, most of them are still unicellular. The cages of both types contain 1 core. In these species of algae, reproduction takes place in two ways - sexual and asexual. Colonial wolvox is usually represented by a number of cells - their number varies from 500 to 60 thousand. The alga is shaped like a ball about 2 mm in diameter. Inside it is filled with mucus. If you follow the movement of the volvox colony, you can see that it is not random, but coordinated. This is due to the fact that the cells are connected together by means of special strands.
Evdorin and pandorin are the most famous volvtcous ones
Relate to the colonial algae and bright representatives of the volvoksovyh class - eudorin and pandorin. The eudorin colony usually consists of 32, 64 or 128 individuals. The cells are in a small lump of mucus, usually forming a spherical shape. Pandorin is also a globular colony of algae. Moreover, it is also mobile. Pandorin is usually found in the same place as the eudorin.
Wolvox and Evolution
Wolvox is an example of a colonial alga that has had a great impact on the evolution process. In volvoksovyh he took place in two major directions. Firstly, during the euphoria, the volvox functions divided the functions of cells into ordinary and sex cells. As is known, the latter method is one of the most important for the emergence of a multicellular biological organism. The second direction in the evolution of Volvoxes is their loss of activity. This direction led to the emergence of terrestrial plants.
Protocols also apply to colonial algae. Algae are useful organisms that are also cultivated by man in artificial conditions. One of the first cultivated species is just the protocoque. The names of algae, which are most often used in industry - it's chlorella and spektressmus. They multiply in a quick and simple way - there is no sexual reproduction, the colony grows due to the formation of daughter cells.
Algae are one of the most ancient living inhabitants of the planet. This species (including colonial ones) is of great importance for life. Colonial algae have the ability to absorb the rays of the sun, falling on the surface of the ocean. They also produce a large amount of organic substances. With the help of algae, ocean inhabitants receive oxygen, and carbon dioxide is absorbed by the colonies. They are also used by man - for obtaining various chemicals, in medicine, radiology, surgery. The products of the life of colonial algae are used in the industry to produce plastics, paints, resins, and paper.