В биологии к колониальным относят два типа живых organisms. First, these are those that consist of a large number of cells. However, these cells do not form organs - their functions are very poorly differentiated. Also this group of organisms differs in that their cells do not form tissue. The next category is individual organisms that accumulate in colonies. Individuals in such colonies have a very similar genotype, there may be several of them in the colonies. Biologists refer to this type of sea sponges, corals, algae.
Green algae
By colonial algae are many ofdepartment of green algae. This category is one of the most numerous in botany - up to 20 thousand different species belong to it. The overwhelming number of green algae species can only live in freshwater bodies of water. Although there are also marine species.
Green algae is represented by five classes. These include the so-called volvox, protococcal, and ulotrix algae. The names of these classes come from the Latin language.
Alga Ulotrix
This type is very common in rivers and other.flowing reservoirs. Usually under water are covered with his colonies. Tina is made up of strands. At the beginning of the growth cycle, the threads are attached to their base with the help of a rhizoid, an elongated cell. Ulotriks - colonial algae, which breeds in three ways: sexually, asexual, and vegetative. This species lives in both sea water and fresh water. The most common type of ulotrix is the so-called belted ulotrix.
The second type of reproduction occurs bymaturing inside zoospore cells - oval-shaped cells that have flagella on the front edge. Subsidiary zoospores, after leaving the mother cell, are still close to it for some time. Then they fall on the underwater object and settle on it. Growing up, zoospores become an adult.
Volvox algae
To colonial algae also includevolvox - algae, the body of which consists of active flagellated cells. This type is derived from the most primitive forms - amoebas. Despite the fact that among the volvoks there are colonial organisms, most are still represented by single-celled organisms. Cages of both types contain 1 core. In these species of algae, reproduction occurs in two ways - sexually and asexually. Colonial Volvox is usually represented by a multitude of cells - their number ranges from 500 to 60 thousand. Algae has the shape of a ball with a diameter of about 2 mm. Inside it is filled with mucus. If you follow the movement of a colony of volvox, you can see that it is not random, but coordinated. This is due to the fact that the cells are interconnected by means of special cords.
Evdorina and pandorina - the most famous volvoksovye
Относятся к колониальным водорослям и яркие representatives of the volvox class - eudorin and pandorin. 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 spherical colony of algae. At the same time it is also mobile. Pandorin is usually found in the same place as Eudorin.
Volvox and evolution
Volvox is an example of a colonial seaweed,had a great influence on the process of evolution. In Volvox, it occurred in two major directions. First, during the elution of the Volvox cells, the functions of the cells were divided into regular and sexual. 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 the Volvox series is their loss of activity. This direction led to the emergence of land plants.
Protococcus algae
To colonial algae also includeprotococci. Algae are beneficial organisms that are also cultivated by man in artificial conditions. One of the first cultivated species is protococcal. The names of algae that are most commonly used in industry are chlorella and scenesmus. They multiply in a quick and simple way - there is no sexual reproduction, the growth of the colony occurs due to the formation of daughter cells.
Algae are among the most ancient livingthe inhabitants of the planet. This type (including the colonial) 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 matter. With the help of algae, ocean dwellers receive oxygen, and carbon dioxide is absorbed by colonies. They are also used by humans - for the production of various chemicals, in medicine, radiology, and surgery. The products of the life of colonial algae are used in industry for plastics, paints, resins, paper.
