Plankton is a living floating mass. It consists of billions of microscopic organisms. This term came from the Greek language and means "wandering", or "floating with the flow."
Water as a habitat
Among the huge variety of terrestrial animal and plant life, it is impossible to find organisms that could spend their whole lives in the air. Even skillful "flyers", such as swallows, can not always be worn under the clouds. Indeed, during the period of nesting, hatching eggs, hatching, they are attached to the ground, however, like other birds. Yes, the birds are not able to fly forever, they periodically need rest. Exactly the same situation with insects. They spend a relatively short time in the air. All of their most important life processes, such as nutrition, reproduction, development, take place on earth. Also, the whole world of plants is connected with the earth's surface, starting from the simplest unicellular and ending with tree species. A completely different relationship with the habitat of aquatic organisms (hydrobios). This is due to the fact that the physical properties of water and air are different. Water has a much greater density and heaviness. It turns out that the lifting force of this medium is greater than that of air. Accordingly, aquatic inhabitants are able to constantly (or at least a long period of their lives) be in suspension in the water column, without touching the bottom. For such organisms, the support is not the soil, but the aquatic environment itself. It is precisely to such living creatures that “soar” in the water column that freely floating or planktonic organisms belong. In fact, plankton is a collection of such living things.
The composition and characteristics of "wandering" organisms
For the most part, very small animals and microscopic algae are plankton - not many of them can be seen with the naked eye. A characteristic feature of plankton organisms can be called a relatively weakly expressed ability to move independently. Most of them are devoid of any organs responsible for movement, and are in the full sense of the word a toy of waves. Being in limbo, plant plankton owes its incredible lightness. Its weight is close to the weight of the water that it displaces. However, animal plankton may contain organisms capable of independent movement. This is explained by the presence of various organs of movement, so that they can swim very lively. However, such movement is very limited. Microorganisms are not even able to withstand the weakest flow of water. And all because the strength of their movement is negligible.
How are the organs of movement arranged?
To begin with, it should be noted that animal plankton is the simplest crustaceans, as well as fish, lobsters and other organisms that are in the stage of embryonic development. German scientists conducted studies that showed that these animals "hover" in the water column is not at all passive. Crustaceans make very active movements at short intervals - they wave evenly with swimming antennae, like birds floating in the air. Complete inactivity of the mentioned antennae will lead to the inevitable lowering of the crustacean to the bottom of the reservoir. Other organs of movement in animal plankton act on the same principle. For example, rotifers, which rotifers are armed with. In fact, planktonic animals can be compared with an airplane, which is kept in the air thanks to the propeller. With the cessation of rotational motion, they slowly plan and sink to the bottom.
"Buffet"
A very important factor for the survival of animal plankton is the fact that the primary source of food, the plant substances that make up plankton, are scattered in the thickness of the water mass, and not attached to the bottom of the reservoir. Thanks to this, animals in abundance find the necessary food for themselves in the elements surrounding them. Algae stocks are able to ensure their existence - this is quite enough to restore the forces that organisms spend on the independent movement necessary for soaring in the water. In addition, plankton (the photos above fully reveal this natural phenomenon) is a very dense mass, which, in turn, serves as a source of nutrition for marine animals and fish. Say, whales are big lovers of this high-calorie food and its main consumers.
Conclusion
Summing up, it should be noted that in the modern world the term in question has one more meaning - office "plankton". These are workers of mental labor, which has a reduced creative component. They spend their lives in offices and other departments. Office plankton includes: accountants, secretaries, managers and others. The origin of the offensive epithet is easy to explain: in fact, all these employees are just small fry. Plankton, in a word.