Phytoplankton Vs Zooplankton: An Overview

Phytoplankton Definition

The free-floating microalgae known as phytoplankton play a significant role in the ecosystems of the ocean, sea, and freshwater bodies of water.

• The terms “phyto” and “plankton,” which both imply drifter in Greek, are combined to form the word “phytoplankton.”
• Since phytoplanktons get chlorophyll to produce their own nourishment, they are autotrophic, much like terrestrial plants.
• The majority of phytoplankton are seen floating on the surface of bodies of water because they need sunshine to prepare their meal.
• Although phytoplanktons are so small that an unaided eye cannot detect them, they are visible as colorful patches on the water’s surface when they are present in large numbers.
• About 1% of the world’s biomass is made up of phytoplankton. The majority of freshwater and marine creatures eat these organisms as their main source of nutrition.
• Depending on different substrates, temperature, and the availability of adequate sunshine, phytoplankton concentrations may vary.
• Diatoms, cyanobacteria, dinoflagellates, green algae, and other different species make up phytoplankton.
• During photosynthesis, these creatures use a variety of inorganic minerals to produce proteins, carbohydrates, and other nutrients for themselves and other animals.
• In contrast to other autotrophs like plants, phytoplankton is made up of a variety of different types of organisms, from bacterial or archaeal prokaryotes to protistan eukaryotes. 
• Half of all photosynthetic activity on Earth is accounted for by phytoplankton, which is also the main contributor to the marine and freshwater food webs.
• These are the main food sources in aquaculture and mariculture and are also used as dietary supplements for different invertebrates in aquariums.
• When nutrients are present in excessive numbers, phytoplankton may grow out of control, developing algae blooms.
• These blooms might create poisonous or even lethal compounds that could disrupt the habitat’s other ecosystems.
• Based on research done between 2015 and 2019, it was shown that global warming is causing the phytoplankton concentration to drop by around 1% per year.
• Diatoms, green algae, cyanobacteria, and coccolithophores are a few examples of phytoplankton.

Zooplankton Definition

Most of the heterotrophic creatures in marine settings are composed of tiny, floating organisms known as zooplankton.

• The name “zooplankton” is derived from the Greek terms “zoo,” which means “animals,” and “plankton,” which means “drifter.”
• In aquatic ecosystems ranging from freshwater to seas and oceans, zooplankton plays an essential role in food chains.
• As heterotrophs, zooplankton rely on phytoplankton and other autotrophs as a source of energy and carbon.
• They can locate food and defend themselves from predators thanks to mobility and water.
• Small protozoans and large metazoans are only a few examples of the creatures that make up zooplanktons. Other creatures, such as immature starfish and worms, may also serve as transient zooplanktons.
• Like phytoplankton, zooplankton species include cnidarians, crustaceans, chordates, mollusks, radiolarians, foraminiferans, and dinoflagellates.
• The majority of zooplankton are the larval stages of fish and invertebrates that eventually go through metamorphosis to become mature marine animals.
• Predation, competition, and breeding are a few of the reasons that limit the dispersal of zooplankton.
• Furthermore, patches of zooplankton can be found in places with favorable environmental factors such as salinity, temperature, and water currents.
• The existence of phytoplankton also restricts the amount of zooplankton, and phytoplankton can have their life cycle interrupted by other variables.
• Zooplankton serves as a food source for higher consumers like fish, making them a crucial component of ocean food chains.
• They may even serve as a conduit for the packing of organic elements in the biological bumps, making this group of creatures significant.
• They also quickly counteract the growing phytoplankton population, causing blooms and halting the negative impacts.
• Some zooplankton has also been linked to removing hazardous substances like mercury from water pollution.
• However, by hosting harmful organisms, zooplanktons also aid in the survival and spread of many illnesses.
• A symbiotic connection exists between bacteria like Vibrio cholerae and crustacean zooplanktons because the exoskeleton of these animals provides the carbon and nitrogen that the bacteria need to survive.
• Animals like radiolarians, krill, jellyfish, immature mollusks, and amphipods are some examples of zooplankton.

Key Differences (Phytoplankton Vs. Zooplankton)

Examples of Phytoplanktons

1. Cyanobacteria

• Cyanobacteria are photosynthetic bacteria that are mostly found in water and use sulfur compounds to chemosynthesis their food.
• Since cyanobacteria are autotrophs and create most of the oxygen in marine settings. They are also known as blue-green algae.
• These make up a sizable subgroup of phytoplankton and are dispersed evenly over all the world’s water bodies. Additionally, cyanobacteria come in various forms, dimensions, and hues.
• Since they are more resilient than other phytoplanktons and can thus endure even harsh aquatic settings, most cyanobacteria are well-suited for various aquatic environments.
• These are primarily found in colonies made up of filamentous or unicellular colonies that are dispersed randomly throughout water bodies.
• Different biomasses are created in distinct regions when the colonies divide from each other to occupy different sites. Lyngbya, for example, has the potential to produce flowers.
• Like other phytoplanktons, cyanobacteria are a source of food for zooplankton.
• Oceanic ecosystems are home to cyanobacteria like Synechocystis, Oscillatoria, Lyngbya, etc.

You may also like to read: Biotic Factors

2. Dinoflagellates

• These unicellular creatures have golden-brown plastids, which give them their golden color.
• The majority of dinoflagellates coexist harmoniously with one another by consuming inorganic minerals and giving them enough oxygen.
• They feature a dented cell membrane, characteristic swimming patterns, a sizable nucleus, and chromosomes that can be seen.
• They are known as dinoflagellates because of the two different flagella that protrude from their cell membrane.
• Despite being an essential component of phytoplanktons that help the ecosystem by providing food and oxygen, they might be dangerous if they grow into blooms.
• Some of them even release poisonous compounds that are damaging to nearby plants and animals.
• Dinoflagellates include organisms including Oxyrrhis marina, Symbiodinium, and Dinophysis acuminate.

Examples of Zooplanktons

1. Jellyfish

• An example of zooplankton that can swim and float through oceans is the jellyfish.
• Nearly every area of the water is home to hundreds of jellyfish, which are all members of the sea anemone or coral family.
• Jellyfish have soft, translucent body that resembles an umbrella and are surrounded by tentacles that dangle off of them. The structure is known as the medusa.
• Jellyfish may be as small as microscopic organisms or as large as one meter in length.
• Zooplanktons like jellyfish serve as a connection between phytoplankton and higher animals since ocean food chains are often shorter than those on land.
• However, the fact that there are more of these jellyfish than usual might potentially be a concern because some of them are large enough to eat the larvae of small fish.

2. Krill

• Krill is an essential component of zooplanktons, a type of crustacean found in oceans all over the world.
• During the day, krill may be seen on the water’s surface; but at night, they migrate deeper into the ocean.
• These are often primary consumers at a lower trophic level, acting as a link between phytoplankton and secondary or tertiary consumers.
• The majority of krill serve as food for bigger marine species.
• Since they may be utilized as food for aquaculture and mariculture, some of them are even caught for commercial purposes.
• They have a chitinous exoskeleton that is primarily transparent, like most crustaceans.
• Krill are bioluminescent creatures with light-emitting photophores that may be crucial for direction and mating.

References 

• Difference between Phytoplankton and Zooplankton
• Phytoplankton vs Zooplankton