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Difference Between Phytoplankton and Zooplankton

Last updated date: 28th May 2024
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What are Phytoplankton and Zooplankton?


The autotrophic (self-feeding) elements of the plankton population and a major component of the ocean, as well as freshwater habitats, are phytoplankton. Phytoplankton, including trees and other plants on the surface, receive their energy by photosynthesis. This implies that phytoplankton must have sunlight since they reside in the oceans and lakes' well-lit surface layers (euphotic zone).

Phytoplankton is spread over a wider surface area relative to terrestrial plants, is subject to less natural fluctuations and has slightly higher turnover rates than trees. As a consequence, phytoplankton immediately reacts to climate variations on a global scale.

The foundation of marine and freshwater food chains is phytoplankton, and it is a crucial factor in the global carbon cycle. They make up about half of the world's photosynthetic activity and approximately half of the production of oxygen, despite the fact that they account for only about 1% of the global biomass of plants.

There are very diverse phytoplanktons, ranging from photosynthesizing bacteria to plant-like algae to coccolithophores plated with armour. Diatoms, cyanobacteria, and dinoflagellates, although several other groups are represented as essential groups of phytoplankton.

Many phytoplanktons are just too tiny for the unassisted eye to be seen separately. Even then, whenever present in sufficiently high numbers, because of the existence of chlorophyll inside their cells and accessory pigments (like xanthophylls or phycobiliproteins) in some species, some varieties may be visible as coloured patches on the surface of the water.


Zooplankton is a form of heterotrophic plankton ranging from microscopic organisms, including jellyfish, to large species. Within bodies of water, such as freshwater systems and oceans, zooplankton is present. The ecologically important species that are an essential part of the food chain are drifting zooplankton.

Types of Zooplankton

Radiolarians, dinoflagellates, crustaceans, foraminiferans, cnidarians, molluscs and chordates are the most significant zooplankton groups.

  • Radiolarians- Radiolarians are tiny protozoan species characterized by the development of silica-made mineral skeletons. The residues of these species, containing a substantial portion of the sediment, could be placed at the base of the oceans.

  • Dinoflagellates- Dinoflagellates are known to be a mixotrophic species, which means that other species may be both photosynthetic or ingested. This form of zooplankton is absolutely tiny and accounts for a substantial proportion of aquatic eukaryotes and seems to be important for coral reef health.

  • Foraminifera- Foraminifera are a kind of protest against amoeboids that show an external shell and ectoplasm that is used for acquiring food. Although the shell is usually composed of calcium carbonate, there are other minerals in the shells of some species. In the drifting or sediment around the upper surface waters, such zooplankton could be located.

  • Crustaceans- Crustaceans were a kind of arthropod consisting of shrimp, krill, crabs, and barnacles. In terms of size, crustaceans vary and represent a major part of the food chain. Krill and copepods, in particular, are significant species of zooplankton.

  • Molluscs- Molluscs, which include sea slugs and squid species and sea snails, are a quite diverse group of organisms. A major component of all aquatic life includes molluscs.

  • Chordates- Animals that have dorsal nerve cord, a notochord, endostyle, post-anal tail, and pharyngeal slits are Chordates. This family is extremely diverse, including scalps, sea stars, and several other animals.

Difference Between Phytoplankton and Zooplankton (Phytoplankton vs Zooplankton)

The answer to the question of what is phytoplankton and zooplankton can be given by phytoplankton vs zooplankton. Below given table below represents the difference between phytoplankton and zooplankton:



Phytoplankton is seen in marine and fresh water and they are plant-like aquatic microbes.

They are marine beings similar to birds. They are also the larval stages of other forms of life.

Examples of phytoplankton may include cyanobacteria, Blue-green algae, diatoms, dinoflagellates.

Examples of Zooplankton may include holoplankton, Meroplankton, crustaceans like krill, and protozoans.

The phytoplankton’s habitat is found to be an Upper sunlight layer of the water bodies (euphotic).

The zooplankton’s habitat is found in deeper ocean beds, the area where it is difficult for sunlight to reach.

When they grow in a group, they turn out to be cloudy patches with brown in colour.

They are Mostly translucent and can be found in distinct shapes and colours.

Lots of oxygen by phytoplankton is liberated.

Lots of oxygen by phytoplankton is consumed.

The mode of nutrition is chemosynthesis or photosynthesis, the way through which it produces its own food.

Zooplankton tends to consume phytoplanktons and zooplanktons.

They are the primary producers.

They are the Primary or secondary consumers

FAQs on Difference Between Phytoplankton and Zooplankton

1. How Does Phytoplankton Die?

Ans. The phytoplankton dies, drown, and disintegrate as they bloom gradually lose their nutrients. The process of decomposition depletes usable oxygen in the surrounding waters, which marine organisms need to thrive. Such oxygen-depleted ecosystems or water resources are also referred to as "dead zones," as species either die through oxygen starvation or leave the region to find waters that are more habitable.

Most sources indicate their own toxins and these species' blooms are toxic to humans. In humans and animals, these toxic algal blooms, or HABs, may induce severe respiratory illness and disease and can lead to the closure of shellfish. Each year, HABs trigger an estimated economic loss of $82 million for the fish, restaurant, and tourism industries.

2. Give Some Importance Shown By Phytoplankton and Zooplankton.

Ans. Importance of zooplankton phytoplankton:

The role of phytoplankton in the global environment has made them a priority for regulating the concentrations of carbon dioxide in the earth's atmosphere. As a way of lowering carbon-dioxide emissions, companies like Climos and Planktos have invested in phytoplankton. To promote their growth, they are exploring fertilizing phytoplankton communities with iron, an essential nutrient. If political and economic demands grow to provide offsets for carbon dioxide emissions, the potential benefit of such businesses increases.

Since zooplankton is not usually harvested by individuals, it has limited control over its movement and has short generation times. They respond quickly and unambiguously to changes in their environment. This makes zooplankton useful ecosystem change markers.