What is plankton and its importance


The term "Plankton" refers to a set of living beings that inhabit the waters, being its most outstanding feature that can only be seen with microscopes. At the etymological level, the word comes from the Greek word "πλαγκτός", which made clear the nature of these spectacular organisms, defining them as "wandering." In addition to these, there are also other specimens that, in some way, come into contact with the plankton, but have the peculiarity of inhabiting and behaving in a different way, such as being constantly moving or living in an area much closer to the boundary with the air.

Plankton can be found at 200m depth or more, however, it does not usually move far from the areas in which it has settled, because, one of the peculiarities that makes it plankton is the continuous suspension in which they are located. They are all very small and transparent, presenting somewhat bluish colors when analyzed under a microscope, however, there are some species that are on the surface and have colors between reddish and bluish, which can be appreciated without much effort. Some even have bioluminescence.

One of the classifications that are considered appropriate to organize these little beings, is divide them into zooplankton and phytoplankton, the former are distinguished by being an integrated group of consumers and producers, whose diversity and quantity varies according to the type of water they inhabit, something that they have in common with the last group, in which most aquatic plants are, produce more than 50 % of oxygen that is in the earth's crust, they feed with the help of photosynthesis and they are the food of zooplankton. Some intellectuals and scientists have opted for a new division of the plankton, following a characteristic such as its size or with respect to the remoteness of the area that inhabit the coast.

What is plankton?

Victor Hensen was the first scientist to use the term plankton in 1887 to refer to the set of organisms that floated at the mercy of the movements of the sea. Therefore, he chose a word that described them so aptly, because plankton means "wandering" or "wanderer."

This set of organisms is very numerous and diverse and inhabits both freshwater and marine waters. It is more representative in the oceans reaching a few trillion amounts and can increase in colder seas. However, in freshwater ecosystems they are usually found in lentic systems such as lakes, ponds or reservoirs since in areas with currents they would be washed away.

In the following Green Ecology article you can learn more about the biodiversity of the oceans.

Plankton Types

The plankton can be classified in several ways. According to your feeding these are distinguished plankton types:

  • Phytoplankton: It is a plankton of a plant nature and, like plants, they obtain energy and organic matter by performing photosynthesis. It lives in the photic layer, that is, the area that receives sunlight, and can reach up to 200 m in the ocean. It is composed of cyanobacteria, diatoms and dinoflagellates.
  • Zooplankton: It is an animal plankton. It feeds on phytoplankton and other zooplankton organisms. It is made up of crustaceans, jellyfish, fish larvae and other organisms. Zooplankton organisms can be differentiated according to the time of their life that belong to the plankton. Holoplanktonic organisms are part of the plankton all their life, while the meroplantonics do so only during one stage, which is normally the larval state.
  • Bacterioplankton: Formed by bacterial communities. They are responsible for the decomposition of the detritus and play a key role in the biogeochemical cycles of some elements (C, N, O, P), weather and trophic chains.
  • Virioplankton: Formed by aquatic viruses. Composed mainly of bacteriophage and eukaryotic algae viruses. They participate in the remineralization of nutrients, in biogeochemical cycles and are part of the trophic networks of plankton.

Most organisms of the plankton have a microscopic size and, therefore, the unit of measurement used is micron (one thousandth of a millimeter). He size Medium ranges between 60 microns and millimeters. In this sense, the different type of plankton that exist are:

  • Ultraplankton: 5 microns Bacteria and small flagellate are included.
  • Nanoplankton: From 5 to 60 microns. Formed by unicellular microalgae such as cocolitoforides and small diatoms.
  • Microplankton: From 60 microns to 1 millimeter. Some unicellular microalgae (diatoms, dinoflagellates), mollusc larvae and copepods (small crustaceans).
  • Mesoplankton: From 1 to 5 millimeters. Fish larvae
  • Macroplankton: Between 5 mm and 10 cm. Sargasso, salps and jellyfish.
  • Megaloplankton: More than 10 cm. Jellyfish

In addition, planting organisms present various body shapes that respond to the needs of the environment in which they live such as buoyancy or water viscosity. Among the strategies or adaptations that have been promoted to float in the water is to increase the body surface, incorporate fat droplets in the cytoplasm and detach from heart, molts and other structures. However, there are some organisms that have a small swimming capacity thanks to scourges and other locomotive appendages such as copepods. Water viscosity changes with temperature, being higher in warm areas and this affects the buoyancy of individuals. Some diatoms have developed cyclomorphosis, that is, the ability to develop different body shapes in summer (long and wide shell with pointed ends) and in winter (short and obtuse shell).

Do you know how many species live in the sea? In the next article we tell you

Climate regulation

The plankton also has the ability to regulate the climate locally on the coasts and seas. It occurs during one of the phases of the sulfur cycle, that of DMS (the acronym for dimethyl sulfide). DMS is responsible for the well-known "smell of the sea". DMS appears when DMSP (dimethylsulfoniumpropionate) is broken down, one of the simple organic compounds that we can find most abundantly in the ocean. Phytoplankton synthesizes and accumulates in its DMSP cells to counteract the effect of seawater salt avoiding dehydration. Thus, the algae release it to the sea when they die and break or when ingested by the zooplankton. The bacteria also use it to obtain carbon and energy and then release the DMS, which escapes into the atmosphere.

In the atmosphere, DMS is oxidized by ultraviolet radiation, and forms sulfate aerosols that condense moisture forming clouds. Since clouds limit the amount of radiation that reaches the earth's surface, they cause a temperature decreaseTherefore, DMS decreases the greenhouse effect.

It is a delicate process because increasing the density of clouds reduces the amount of ultraviolet radiation that reaches the surface of the sea where the phytoplankton is located and it stops producing DMSP.

In conclusion, we should not underestimate the importance of the organisms that inhabit the Earth because these tiny beings have shown that they have great power over the processes that govern this planet, which makes it necessary to deepen their knowledge and prevent their loss.

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