What does plankton eat?

In this article we are going to answer what plankton eat, what is plankton, what plankton needs to survive, what kind of animals eat plankton, can plankton hurt humans, and why plankton glow. 

What does plankton eat?

Phytoplankton eats through photosynthesis where they use chlorophyll and sunlight to create energy. 

They take in carbon dioxide and release oxygen. Apart from photosynthesis to create their food, phytoplankton also relies on some nutrients found in the water such as phosphate, nitrate, and calcium. 

Zooplankton eats phytoplankton and in small quantities, they can eat algae and other smaller creatures. 

What is plankton?

Plankton is a group of microscopic plants and animals that are the foundation of the freshwater and seawater food pyramid. They are the base of the marine ecosystem and provide an entire marine food web.

Plankton moves with the natural movements of water, they do not swim or stay in one place. There are 4 types of plankton known as:

  • Phytoplanktons are plants that make their food through photosynthesis such as other plants. They are known as microalgae and are responsible for a major part of the production of oxygen. 
  • Dinoflagellates use flagella to move in the water, they do not need water movements to move. 
  • Diatoms have shells and their structure is rigid. They rely on the movements of water to move. 
  • Zooplankton is an animal that eats phytoplankton and then is eaten by other sea animals such as fish and crustaceans. 
  • Bacterioplankton are bacteria
  • Virioplankton are viruses

The 4 types of plankton can be found in saltwater and freshwater. While they are needed to maintain marine life if they are found in a high proportion they can be toxic and cause severe damage to the oceans. Plankton in high quantities can release toxins that cause damage to fish. 

Climate change, rising temperatures, and chemicals that are thrown into saltwater and freshwater are putting plankton in danger. Without plankton, there would not be any species in the ocean that could survive. 

What plankton needs to survive?

Plankton needs their food to survive and some nutrients that are found in saltwater and freshwater such as calcium phosphate, nitrate, and copper. Phytoplankton especially need water and sunlight to survive while zooplankton need phytoplankton which is their main food. 

The most important nutrients for plankton to live are nitrogen and phosphorus which both are found naturally in water but some locations might have a shortage of nitrogen and plankton can not live there. 

Some plankton can survive without sunlight just for a few days but they are more affected by high water temperature than by sunlight. 

What kind of animals eat plankton?

Phytoplankton is eaten by zooplankton which then is eaten by fish and crustaceans and other larger sea animals. 

Krill is the most popular sea animal that eats zooplankton and then they are served to a huge variety of fish such as salmon, rockfish, sardines, whales, and seabirds. Shrimps are the second-largest consumer of zooplankton. 

Forage fish such as anchovies, smelt, halfbeaks, herrings, sardines, capelin, butterfish, rockfish, and menhaden eat plankton too. 

Can plankton hurt humans?

Yes, plankton can hurt humans by producing toxins. Not all plankton will hurt humans but there are a few species of plankton that can create toxins that can harm humans. Dinoflagellates and diatoms can create chemicals that if ingested by humans will cause symptoms such as

  • Diarrhea
  • Paralysis
  • Dizziness
  • Memory loss

The most common way that these toxins will get to humans is if they eat a fish that has been eating dinoflagellates or diatoms. Toxins can build up in fish flesh and cause food poisoning in humans. 

Why does plankton glow?

Not all plankton glow. There is a species known as bioluminescent plankton that glows when they are agitated by waves. They glow because they have a chemical known as luciferin, which creates light. Bioluminescent plankton release luciferin as a mechanism of defense. 

Dinoflagellates can produce luciferin without the need of a predator and their light is known as cold light because it does not produce any heat. 

Follow this link for a video on how bioluminescent plankton glow


This article answered what plankton eat, what is plankton, what plankton needs to survive, who eats plankton, can plankton hurt humans, and why plankton glow.



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