What Is Plankton

by Assistant Vagabond

Reading time: 2 – 4 minutes

Planktons are small organisms that are found in the upper levels of the water in oceans, lakes and rivers.  Its name in Greek literally means “drifter” or “wanderer”; denoting the immobility of plankton to move horizontally through the water.

And though plankton can move vertically, its diminutive size cannot go against strong waves, so their horizontal movement depends largely on the direction of the ocean’s current. They are situated in different levels of the ocean depending on the amount of sunlight available.

Another reason for this is that plankton ecosystems generally rely on their access to solar energy for photosynthesis. These organisms thrive on ocean levels where there are abundant amounts of nutrients and sunlight. They are also categorized according to their ecological niche, meaning that unlike other organisms that are labeled based on their phylogenetic or taxonomic classifications, plankton is recognized by its effect on the ecological system as a whole.

Plankton is also one of the main sources of food for fish. They are the most common prey for all fish larvae, and large sea mammals such as whale sharks or blue whales.

Plankton is generally divided up into 3 functional categories:

Phytoplankton are a group of plankton that reside near the surface of the water where there is enough light to sustain photosynthesis. The important groups in this classification are coccolithophores, cyanobacteria, diatoms and dinoflagellates.

The next category is Zooplankton. This group comprises of small protozoans and metazoans, this includes crustaceans such as crabs, lobsters and crayfish among others that prey on this group of plankton.

The last kind of plankton is Bacterioplankton. They are mostly bacteria and archaea, organisms that play an important factor in transforming organic molecules into inorganic forms down the water column.

Plankton has its place in the lower regions of the food chain and is the basic source of food for small aquatic animals like fish larvae. During the early stage of their life cycle fish rely on their yolk sac for nutrition. But once the supply is consumed, the fish larvae switches to plankton as a food source.

Fish rely on plankton to survive during its development stage. And if the number of plankton decreases, the population of fishes will be greatly affected. This cycle clearly demonstrates the impact of plankton upon all ocean wild life.

Aside from its role in the lower levels of the food chain, the plankton ecosystem play a major role in our planet’s biochemical cycles out of the many chemical cycles that exist.

Plankton, though miniscule in size, plays a large role in our planet’s everyday survival. From its initial impact to lower species in the food chain to its role in fixing biochemical systems, shows that every organism that exists in this planet has a specific task to fulfill to ensure the existence of other species like blue whales, vampire squids whether large or small. There is no doubt that without plankton and its effects on a global scale; the cycle of every organism that exists will be at risk.

While the smallest and a mere drifter or wanderer the plankton is essential for the life cycle of our planet’s oceans.


  1. Plankton And Oxygen
  2. What Are Phytoplanktons?
  3. Uses Of Plankton
  4. Phytoplankton And Cancer
  5. Health Benefits Of Phytoplankton

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