What do plankton eat?

What Do Plankton Eat?: A Complete Guide

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The tiny, drifting organisms that live in oceans and seas are called plankton. They’re responsible for taking up food particles from seawater and producing 60% of all oxygen on Earth! So, what do plankton eat?

While they may seem like tiny organisms, plankton hold immense importance to our oceans and freshwater. They act as the base of all marine life through their role in trapping food particles that drift around sea currents with open mouths called “gills” on either side! The word comes from Ancient Greek meaning “drifter” due to these creatures’ mobility when feeding or migrating.

There are two types of plankton: phytoplankton and zooplankton. Phytoplankton is plant-like, meaning they rely on photosynthesis for energy. Zooplankton is animal-like and must consume other organisms for food. Both types are eaten by more giant sea creatures and, eventually, us!

What Do Plankton Eat?

Plankton is like plants on land in that they produce their food through a process called photosynthesis. Plankton can be considered sustainable through this recycling system of converting sunlight into energy and storing it as glucose, which becomes nutrients for future use.

Most planktons are too small to see without a microscope, but they are essential to the marine food web. Phytoplankton is plant-like plankton that use photosynthesis to make their food. These microscopic plants float near the water’s surface and provide food for zooplankton, tiny animal-like plankton. Zooplankton feed on phytoplankton and are, in turn, eaten by larger animals. Some types of zooplankton also eat other zooplankton.

Phytoplankton is at the very bottom of the food chain and is critical to our oceans’ health. They produce oxygen and remove carbon dioxide, helping to regulate our planet’s climate. These single-celled plants float near the water’s surface and use sunlight to create food.

what do plankton eat

Plankton consume nitrogen.

Phytoplankton need only three things to survive: sunlight, water, and nutrients. The most common nutrients come from the ocean floor, where phytoplankton drift and sink to feed. These include nitrogen, phosphorus, and silicon. Nutrients can also come from pollution and runoff from the land. Too many of these can be harmful to phytoplankton and cause algae blooms.

Zooplankton are tiny animals that drift in the ocean currents. They include crustaceans, mollusks, fish eggs, and larvae. Like phytoplankton, zooplankton is at the bottom of the food chain. They are essential because they provide food for larger animals and help to recycle nutrients in the ocean.

Glucose is converted into energy in cellular respiration, producing adenosine triphosphate (ATP), the primary molecule that carries significance for organisms. While plants on land take up carbon dioxide and release oxygen as they grow, phytoplankton is also abundant within ocean waters, making them one of Earth’s major producers-alongside green algae—of this essential nutrient needed by all living things to live healthy lives.

Nutrients That Plankton Needs:

Plankton provides a critical service to our planet by producing oxygen and removing carbon dioxide. They are at the bottom of the food chain and provide food for larger animals. Plankton needs only three things to survive: sunlight, water, and nutrients. The most common nutrients come from the ocean floor, where phytoplankton drift and sink to feed. These include nitrogen, phosphorus, and silicon. Nutrients can also come from pollution and runoff from the land. Too many of these can be harmful to phytoplankton and cause algae blooms.

what do plankton eat

Sunlight gives plankton necessary energy.

One of the essential nutrients in ocean plankton is phosphate. It helps to build their cell walls and keep them healthy, giving off energy through photosynthesis! Apart from this crucial ingredient, though, phytoplanktons need other vital components such as calcium, iron, and silicon nitride – all of which can be found naturally on Earth’s crust or sourced remotely if necessary.

Plankton is an integral part of the marine food web and plays a vital role in the health of our oceans.

Who Eats Plankton?

The food chain is a series of animals that get their energy from eating other living things, starting with zooplankton and moving up to more giant creatures. Some huge marine life may also be able to take blood meals on top, but what makes this ecosystem hum? The vast numbers. A single blue whale can consume up to 40 million krill in a day. A single great white shark could theoretically eat nearly 28 tons of fish and marine mammals in one year. That’s a lot of plankton!

Zooplankton are tiny animals that drift in the ocean currents. They include crustaceans, mollusks, fish eggs, and larvae. Like phytoplankton, zooplankton is at the bottom of the food chain. They are essential because they provide food for larger animals and help to recycle nutrients in the ocean.

Environmental Importance Of Plankton

With a mass between 0.1 and 1000 metric tons, phytoplankton make up more than half of all aquatic life on Earth’s oceans! These microscopic organisms rely heavily upon environmental conditions found only here-in seawater with enough sunlight to survive. They can be used as an excellent resource for studying changes within our climates and those throughout global warming patterns across different regions around this planet.

These creatures are vital players in our understanding of how the environment changes. They provide early warning signals that could indicate problems before they become too severe, such as changes to climate or sea levels.

Carbon Influence Of Plankton

Phytoplankton are microscopic plants that live in oceans around the world. They use photosynthesis to pull carbon dioxide from Earth’s atmosphere and convert it into organic matter, which also supports entire food chains! In this way, these microscopic organisms significantly impact our planet’s climate.

As organisms at the base of the marine food web, phytoplankton is eaten by larger plants and animals. Their carbon-rich bodies sink to the ocean floor when they die and are eventually recycled into sedimentary rock. This process stores carbon in the Earth for a long time, keeping it out of the atmosphere where it could contribute to global warming.

Because phytoplankton plays an essential role in the carbon cycle, their abundance and distribution can significantly impact Earth’s climate. For example, warmer ocean temperatures can cause phytoplankton to grow more quickly. This can lead to more carbon being stored in the ocean, which would help offset some of the carbon dioxide emissions from human activity that are causing global warming.

Final Words

Plankton is an integral part of the marine food web and plays a vital role in the health of our oceans. They provide food for larger animals and help to recycle nutrients in the sea. Additionally, phytoplankton plays a crucial role in the global carbon cycle by absorbing carbon dioxide from Earth’s atmosphere and converting it into organic matter.

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What Do Phytoplankton Eat?

What Do Phytoplankton Eat?

The world’s oceans are filled with microscopic plants called phytoplankton. Sometimes called the “plants of the sea,” phytoplankton form the bottom of the aquatic food chain, serving as nutrition for a wide range of organisms, including fish that humans catch and eat. Phytoplankton, however, make their own food through the process of photosynthesis.

Plankton Definition

Plankton means “to wander or drift.” Phyto comes from the Greek word for plant. Phytoplankton therefore are drifting plants found in aquatic environments like oceans, rivers and lakes. Phytoplankton range from photosynthetic bacteria to diatoms and dinoflagellates.

Phytoplankton contain chlorophyll which allows them to convert sunlight into energy. In the process known as photosynthesis, phytoplankton use energy from sunlight to combine water and carbon dioxide to form glucose, a form of sugar, which they store as carbohydrates to use as nutrients.

Like plants on land, phytoplankton convert the sugar to energy in the process called cellular respiration. The sugar is converted into adenosine triphosphate (ATP), the form of energy organisms can use. So, it could be said that photosynthetic plankton eat sunshine.


Along with sunlight, water and carbon dioxide, phytoplankton require a variety of other nutrients from the water including nitrogen, phosphorous and iron. The most important are nitrogen and phosphorous which are essential to survival and reproduction. Nitrogen is in short supply in some areas but in other areas, phosphorous is limited. Phytoplankton cannot continue to grow when one or the other has been used up.

The nutrients phytoplankton require are created in nature when rocks weather and from atmospheric conditions that convert nitrogen gas into a usable form. In addition, humans introduce phosphorous and nitrogen to the water as runoff from such things as detergents, sewage and fertilizers.

Environmental Importance

The fact that phytoplankton are common, live in all the Earth’s oceans and rely on basic environmental conditions found in seawater and sunlight makes them a good source of study on changes in the environment and climate. Scientists can study their abundance or chemistry, viewing them as early warning signals of changes in the earth’s climate, seawater or other environmental conditions.

Although minuscule in size, phytoplankton have a large effect on our world. Their abundance in the oceans, with their process of photosynthesis and use of carbon dioxide, helps ensure a balance in the carbon that is transferred along the food chain. The more phytoplankton pulls carbon dioxide from the environment, the lower the amount of this gas. Some theorize that by using carbon dioxide in the nutritional process, phytoplankton populations help decrease carbon dioxide levels that contribute to global warming.


Phytoplankton are on the bottom of the aquatic food chain, so their nourishment and population growth are essential to other creatures from the small fish that eat them, to larger fish and eventually, humans. If phytoplankton cannot survive, they cannot support the other organisms that eat the phytoplankton and those organisms also die.

From tiny zooplankton to filter-feeders like giant larvacean and barnacles to whales, most of the marine food chain depends on phytoplankton. A notable exception lies along deep ocean vents where chemosynthetic bacteria form the base of the food chain.


The microscopic plants and animals of the plankton family are the foundation of freshwater and seawater food pyramids.

Biology, Climatology, Earth Science, Ecology, Geology

Assorted Plankton

The varied translucent plankton against a black background.

Though they are microscopic in size, organisms called plankton play a big role in marine ecosystems. They provide the base for the entire marine food web . The word plankton comes from the Greek word planktos, which means “drifter.” Their name fits, because plankton do not swim on their own or stay in one place like coral. They drift about in the water, allowing tides, currents, and other factors determine where they go.

There are two main types of plankton : phytoplankton , which are plants, and zooplankton , which are animals. Zoo plankton and other small marine creatures eat phyto plankton and then become food for fish, crustaceans , and other larger species.

Phyto plankton make their energy through photosynthesis , the process of using chlorophyll and sunlight to create energy. Like other plants, phyto plankton take in carbon dioxide and release oxygen. Phyto plankton account for about half of the photosynthesis on the planet, making them one of the world’s most important producers of oxygen. Phyto plankton rely on nutrients found in their surroundings, such as phosphate, nitrate, and calcium, to thrive.

In addition to phyto plankton and zoo plankton , two even smaller kinds of plankton can be found floating in the sea. Bacterioplankton are bacteria and virioplankton are viruses.

Plankton can be found in saltwater and freshwater. One way to tell if a body of water has a large plankton population is to look at its clarity. Very clear water usually has less plankton than water that is more green or brown in color.

While plankton populations are needed for thriving marine ecosystems, too many plankton in one area can create a serious environmental problem. When a plankton population suddenly swells, it is called a “bloom.” When this happens with certain types of phyto plankton that release dangerous toxins, the region may experience a red tide or other serious algal bloom . These temporary conditions can cause high fish mortality and other damage to the marine ecosystem. Contaminated fish that are caught and served to people may also cause illness and even death.

Because the aquatic food chain depends so heavily on plankton, the survival of these tiny plants and animals is essential for healthy marine ecosystems. Climate change and rising sea temperatures pose serious risks to plankton populations.

National Geographic Explorer Gabrielle Corradino is a U.S. Department of the Interior Climate Science fellow whose research interests include the role of plankton in the marine food web. The more that scientists like Corradino understand how to protect these critical marine species, the more likely it is that their research will help creatures further up the food chain survive threats such as climate change.


Ever look in a tide pool and think nothing’s living there? Try taking another look. It’s probably inhabited by millions of tiny plants and animals. Some of them you might be able to see floating around if you scooped up some of the water in a glass jar, and some you might need a microscope to see. These tiny creatures are referred to as “plankton.”

Plankton includes plants and animals that float along at the mercy of the sea’s tides and currents. Their name comes from the Greek meaning “drifter” or “wanderer.” There are two types of plankton: tiny plants–called phytoplankton, and weak-swimming animals–called zooplankton. Some are babies that will grow into strong-swimming, non-planktonic adults. Others will remain plankton for their entire lives. All jellyfish, and the Ocean sunfish are such feeble swimmers that they too are included as plankton. Most of the plankton in the ocean are plants.

Phytoplankton produce their own food by lassoing the energy of the sun in a process called photosynthesis. So for sunlight to reach them, they need to be near the top layer of the ocean. So must zooplankton, which feed on the phytoplankton. Plankton have evolved many different ways to keep afloat. Spikes, like those on a radiolarian, help to distribute its weight over a large surface area and slowing its sinking. Many organisms, such as copepods and diatoms, produce oil to keep them afloat. The Portuguese man-o-war uses an air-filled sac to stay afloat.


Phytoplankton is made of very tiny–usually one-celled–plants. Since plants make their own food and release oxygen as a byproduct, all the other living things in the ocean depend on them directly or indirectly for food or oxygen. It is estimated that 80% of the oxygen on earth is produced by phytoplankton.

Diatoms are the most common type of phytoplankton. They are single-celled yellow algae whose cell walls contain a lot of silica, glass-like substance. The actual diatom fits inside this cell wall, with one half of the wall fitting over the second half, like a lid. The name diatom actually means “cut in two” in Greek. There are many different kinds of diatoms, and they come in a variety of shapes–disk shaped, needle shaped, or linked together in chains.

Dinoflagellates are like both plants and animals: they can move themselves through the water using two flagella in grooves along their body; yet they can also produce their own food like plants. Two species of dinoflagellates, Gonyaulax and Gymnodinium , are the cause of the dangerous red tide. When their populations get large, the reddish-colored dinoflagellates not only make the surrounding water appear to be tinted red, they can produce a variety of toxic effects, including fish mortality and paralytic shellfish poisoning.


Zooplankton, or animal plankton, may spend their entire lives as plankton at the mercy of the currents (holoplankton); or as meroplankton, existing as plankton for a short time during their development.

Radiolarians, tiny one-celled animals related to ameobas, live in glass-like shells and sometimes have long spines that radiate from holes in their shells. These projections are called “false feet,” or pseudopodia, which they use to move. Radiolarians are part of the group sarcodina (meaning “creeping flesh”), whose members move by expanding and contracting projections of their jelly-like bodies.

Forams are also members of the sarcodina group. They start life with a one-chambered shell, and add compartments as they grow. Their pseudopodia project out through holes in the shell. They feed on diatoms and other protozoans by secreting digestive juices into their food to dissolve it.

Zooplankton can also be categorized according to size: nannoplankton are unicellular animals that feed on phytoplankton and are in turn eaten by other zooplankton (5/1000 mm to 60/1000 mm); microplankton (60/1000 mm to one mm) are composed primarily of eggs and larvae, usually of invertebrates; macroplankton (over one mm) often contain large numbers of copepods, along with amphipods, cumaceans and arrow worms; and megaplankton include mainly the large jellyfishes and their relatives the Portuguese man-o-war and the By-the-wind sailor, which move at the mercy of the currents.

Comb jellies (~6 inches long) are not jellyfish but belong to a separate group that does not sting. They are bioluminescent–that is, they can make their own light. Photo courtesty of the Lloyd Center for Environmental Studies

(From “The Intertidal Zone.” Courtesy of Bullfrog Films and the National Film Board of Canada)


Because phytoplankton make their own food using the energy of the sun (in a process called photosynthesis), they are called “producers.” That places them at the very base of the food web. Many animals eat plankton directly, or feed on animals that eat plankton. Animals that eat plants or other animals are called “consumers,” and bacteria that break down dead plants and animals are called “decomposers.”

Can Plankton Be Harmful for the Environment?

While plankton are vital for food chains and in sustaining ecosystems, too much of them can contaminate environments too and can cause serious problems at sea.

You can tell how much plankton a body of water has by looking at its purity. Plankton concentrations tend to be lower in crystal-clear water than in water that is greener or more brown in hue. However, when the population of plankton increases uncontrollably, certain types of phytoplankton can contaminate the marine environment by releasing harmful toxins that can cause red tides. These conditions can poison fish and other marine life and therefore cause great damage to the ecosystem.

Since plankton are the foundation of aquatic food chains, these tiny microorganisms are essential to be kept at a balance. However, unsteady sea temperatures and climate change pose threats in keeping the plankton population controlled.

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