Plankton - Definition, Types, Examples and Importance

Plankton Definition: Plankton, deriving from the Greek word meaning "drifter" or "wanderer," are minute organisms that inhabit aquatic environments and are transported by the movement of tides and currents. These organisms cannot effectively swim against these natural forces. Playing an essential role in marine ecosystems and the marine food chain, plankton is a significant food source for a wide array of large and small marine organisms. Additionally, they contribute significantly to the ocean's ecological balance by absorbing carbon dioxide and producing oxygen. Refer to the NEET Biology Notes in the following article for more in-depth details on plankton.

What is Plankton?

Explore NEET Online Courses by PW

Types of Plankton

Mammary Glands

Classification of Plankton by Trophic Level

• Phytoplankton: These are plankton that resemble plants and are autotrophic, meaning they can produce their own food through the process of photosynthesis. Phytoplankton contribute significantly to global photosynthesis, generating oxygen and absorbing carbon dioxide. They exist in diverse forms, such as diatoms, cyanobacteria (commonly known as blue-green algae), dinoflagellates, and coccolithophores.
• Zooplankton: Zooplankton are plankton that exhibit animal-like characteristics and are heterotrophic, meaning they rely on other organisms for sustenance. They primarily feed on phytoplankton, bacteria, and other minute organisms. Examples of zooplankton include copepods, krill, foraminifera, jellyfish, and the larvae of various marine animals.
• Mixoplankton: These organisms can function as both autotrophs and heterotrophs depending on the prevailing environmental conditions.

Okazaki Fragments

Classification of Plankton by Size

• Femtoplankton: These are the smallest plankton, measuring less than 0.2 micrometres. They are predominantly composed of viruses.
• Picoplankton: Ranging in size from 0.2 to 2 micrometres, picoplankton consist mainly of bacteria.
• Nanoplankton: These plankton are sized between 2 and 20 micrometres and include certain protists and small algae.
• Microplankton: Ranging from 20 to 200 micrometres, microplankton encompass most phytoplankton, some protozoans, and large protists.
• Mesoplankton: These plankton are of medium size, ranging from 0.2 to 20 millimetres. They include numerous copepods and other small crustaceans.
• Macroplankton: Macroplankton are larger plankton, measuring from 20 millimetres to 2 centimetres. They include jellyfish, salps, and some pteropods.
• Megaplankton: The largest type of plankton, megaplankton are greater than 2 centimetres in size. They include jellyfish, salps, squid, and some tunicates.

lymphocytes

Plankton Examples

Gametes Types

Importance of Plankton

1. Oxygen Production: Plankton, particularly phytoplankton, play a essential role as producers, responsible for around half of the oxygen generated through photosynthesis.
2. Food Source: Fisheries rely on plankton as a primary food source, highlighting their significance in marine food chains.
3. Nutrient Recycling: Plankton contribute to nutrient recycling by converting dead organic matter into inorganic nutrients essential for plant growth.
4. Carbon Dioxide Fixation: Phytoplankton aid in carbon dioxide fixation, a vital process for regulating greenhouse gas levels.
5. Nitrogen Fixation: Certain plankton species can fix atmospheric nitrogen into ammonia and nitrates, essential nutrients for phytoplankton growth.
6. Oxygen-Carbon Dioxide Balance: Both phytoplankton and zooplankton are essential for maintaining the balance of carbon dioxide and oxygen in the environment.
7. Bioluminescence: Bioluminescent plankton contribute to the blue flashes of light seen in the sea, adding to the marine ecosystem's diversity and beauty.
8. Harmful Algal Blooms: Some plankton species, like dinoflagellates, can lead to harmful algal blooms known as red tides, which can produce toxins harmful to marine life.

Free Study Material for NEET Preparation

Plankton Plant

Plankton Fish

Plankton Algae