Difference Between Phytoplankton and Zooplankton

The term ‘plankton’ comes from a Greek word that means “wanderer” or “drifter,” which refers to the tiny species that float along ocean currents and drift along in bodies of fresh water.


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Zooplankton and phytoplankton are the two types of plankton found in the oceans. Even though they live in the same waterbody, have identical size, and are both vital to the marine environment, the two different forms of planktons have distinct characteristics. 

Phytoplankton vs Zooplankton

Phytoplanktons are plants, whereas zooplanktons are animals. A typical example of phytoplankton is algae or diatom, and an example of zooplankton are crustaceans such as krill. These two planktons usually float on the water’s surface. 

Phytoplankton vs Zooplankton

Phytoplankton is free-flowing autotrophic plankton. It is often referred to as microalgae. They can be either photosynthetic planktons or chemosynthetic algae and are found in both marine habitats as well as freshwater. Phytoplanktons are the major producers of the oceanic environment.

Zooplankton is a group of floating organisms. They are heterotrophic in nature and are found in both fresh water and marine habitats. They are mostly found in lower regions of the water body.

Comparison Table

Parameters of ComparisonPhytoplanktonZooplankton
MeaningPhytoplankton is a free-floating plant-like structure that is present on the water’s surface.Zooplankton is an animal-like group of organisms that are free-floating on water’s surface.
AppearanceIt looks like cloudy patches when in place, green-colored to brown color.These are mostly transparent. Found in varying shapes and sizes.
Found inFound on the water surface as they require sunlight.  Found in deeper and darker regions of the ocean, away from sunlight.
Mode of nutritionThey produce their food by photosynthesis or chemosynthesis. They are autotrophic.They depend on phytoplankton and other zooplankton. They are heterotrophic.
FunctionsThey act as food for zooplankton and helps in the indication of marine health (e.g., in the case of red tides).  They act as food for higher heterotrophs. Helps in the indication of the presence of the toxic substance in the marine environment.
PhotosynthesisPhytoplanktons are capable of photosynthesis.Zooplanktons are incapable of photosynthesis.
EnergyPhytoplanktons get energy by means of photosynthesis.Zooplanktons get their energy by feeding on other planktons.
Food chain supply positionPrimary producersPrimary or secondary consumers
ExamplesCyanobacteria, Blue-green algae, diatoms, dinoflagellates, and coccolithophoresMeroplankton, crustaceans (krill), mollusks, holoplankton, chordates, radiolarians,  protozoans, and foraminiferans

What is Phytoplankton?

Phytoplankton is free-flowing autotrophic plankton and is often also known as microalgae. They can be either photosynthetic planktons or chemosynthetic algae.

Phytoplanktons are photosynthetic plants as obtain energy through the process of photosynthesis and take up nutrients from their surrounding environment.

They are tiny microorganisms and cannot be seen by our naked eye, but they appear cloudy when present in masses. Phytoplankton constitutes approximately 1% of the world’s total biomass.


What is Zooplankton?

Zooplankton is a group of floating organisms, heterotrophic in nature, found in both fresh water and marine habitats. They are mostly found in lower regions of the water body.

Zooplanktons are often found in deeper parts or in the middle parts of the oceans as they do not require sunlight and tend to travel to the surface for feeding and also in order to escape their predators.

Some of the typical examples of zooplanktons are meroplankton, crustaceans such as krill, mollusks, chordates, radiolarians, jellyfish, protozoans, and foraminiferans.


Main Differences Between Phytoplankton and Zooplankton

  1. Phytoplanktons are found on the surface of the water body, while zooplanktons are found on both surfaces as well as the interior of the water body.
  2. Phytoplanktons prepare their food, i.e., They are capable of photosynthesis while zooplanktons are not.
Difference Between Phytoplankton and Zooplankton


  1. https://aslopubs.onlinelibrary.wiley.com/doi/abs/10.4319/lo.1996.41.7.1572 
  2. https://www.nature.com/articles/nature02593 

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