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Marine Biota Along With the Definition, Benefits and Images

by Zidni

The earth consists of oceans and land, where the ocean is the largest part of the earth which is about 2/3 of the earth. The sea is a habitat for various kinds of organisms that have evolved and adapted to their environmental conditions. All types of living things that exist in the sea, both animals, plants, and corals are referred to as marine biota.

Throughout the oceans, the types of organisms or marine biota are not evenly distributed. Characteristics of diverse marine environments cause the creation of different habitats and influence the types of organisms that inhabit them. The characteristics of the ocean include light availability, water depth, and the complexity of the sea topography.

Types of Marine Biota

Broadly speaking, marine biota is classified into 2 large groups, namely plants and animals. But in its development, the two groups are divided into several types which are seen from the characteristics and characteristics possessed. The grouping of marine biota based on their characteristics is :


Plankton is a type of microscopic organism that lives in the upper or surface (pelagic zone) of the ocean, sea, or other waters. The name Plankton derived from the Greek which means wanderer. In general, Plankton has a small size that is less than 1 mm or about 0.000039 inches.

But there are also types of plankton that have a large size, for example, jellyfish that have a width and length of tentacles reaching up to 15 meters.

Plankton comes from the remains of plants and marine animals. This organism has been considered as a food source for large organisms that live in waters such as fish, shellfish, coral, and whales. Although it is classified as a living organism, plankton does not have the power to fight currents, tides, or the winds that wash it away. Seacoast is a good habitat for the development of plankton, where coastal areas contain mineral salts and sunlight which are good for plankton.

Plankton types

Based on its nature, plankton is classified into 3 types, that is :

1. Phytoplankton

Phytoplankton is a microscopic organism that lives in the euphotic zone (dim surface) of the sea that is able to synthesize its own food in the form of organic material that is processed from inorganic materials with the help of sunlight. Besides being able to produce food for themselves, phytoplankton is also a provider of energy for almost all life in the sea. The name phytoplankton comes from the Greek phyton which means plants and plankton which means wanderers.

Types of phytoplankton include:

  • Cyanobacteria

Cyanobacteria or commonly called blue algae. It belongs to a type of bacteria and is the first organism on earth that was developed through photosynthesis. He is also one of the organisms capable of taking and processing nitrogen from the air into organic molecules which can later be utilized by plants and animals.

2. Diatoms

Diatoms are protists, a type of algae that has a single cell with a protective cell wall made of silica. This is the most abundant type of phytoplankton. In favorable conditions, diatoms can reproduce rapidly so that their presence is able to dominate an area of ​​water. But if conditions are not favorable, such as the occurrence of winter or when the source of nutrients decreases, these organisms can sink to a lower level until the current returns them back to the surface.

3. Dinoflagellata

Even though both Dinoflagellata and diatoms belong to protists, but they have different physical properties. Dinoflagellata has a motion device in the form of a vibrating whip (flagellum) in which there are receptor cells that are used as sensory devices to determine the state of the environment and as a tool to capture food.

This type of phytoplankton plays a role in the emergence of red tide symptoms which are events in which the sea waters appear to be reddened. This condition was caused by the explosion of the population of the dinoflagellates which could result in the mass death of other marine residents due to poisoning.


Zooplankton is a type of organism that mostly lives in surface waters with a body size of more than 0.05 mm. Zooplankton is a category that covers various sizes of organisms including small protozoa and large metazoans.

Zooplankton species are not evenly distributed but randomly within a sea area. Zooplankton is classified as a type of aquatic animal whose food sources are other phytoplankton and zooplankton and zooplankton can also act as a reservoir of disease.

Based on its life cycle, zooplankton can be divided into 2 groups, that is:


Meroplankton (temporary plankton) which spends part of its life as plankton, especially at the larval level.

2. Holoplankton

Holoplankton (fixed plankton) which spends its entire life as plankton.

Whereas when viewed from its size, zooplankton is divided into 4 groups, that is:

  1. Microplankton which has a size of 20 to 200 µm
  2. Mesoplankton which has a size of 200 µm to 2 mm
  3. Macroplankton that has a size of 2 to 20 mm
  4. Micronekton which has a size of 20 to 200 mm
  5. Megaloplankton which has a size of more than 200 mm

Organisms belonging to zooplankton include:

  1. Copepoda is a type of crustacean that has a length of about 1 to 2 mm. But some other types have a larger size. This species has only one eye. Most species eat single-celled phytoplankton, and nati in turn, Copepoda will be a portion of food for fish or other larger aquatic animals.
  2. Krill is a type of crustacean similar to shrimp with a body length between 1 and 2 cm. Even though it is still carried away by water currents, this type of plankton has the ability to swim. That is why krill is not fully regarded as plankton. Most of these krill species from a herd which consists of billions of these species. Krill is a portion of food for several types of aquatic animals such as whales.
  3. Jellyfish is one of the aquatic animals belonging to the largest type of plankton. The diameter of his body can reach 2 meters with a tentacle length of up to 15 meters. Jellyfish consume several types of zooplankton and small fish.
  4. Larvae of fish, marine worms, corals, and several other aquatic species have been considered as zooplankton groups.


Bacterioplankton is a group of bacteria that during their lifetime worked to decipher the remains of other organisms. Just like phytoplankton, bacterioplankton is also capable of carrying out photosynthesis itself. This species can be found in almost all parts or levels of the sea, not only in surface areas such as other plankton species.

Bacterioplankton describes the remains of other organisms so that their nutrients can be used again and become a food source for zooplankton. These types of bacterioplankton include phytoplankton, fungi, and other fungal organisms that are significant in the nutrient cycle.

Based on its size, plankton is classified into several types, that is:

  1. Megaplankton – Megaplankton which are more than 20 cm (20 to 200 cm) in size, for example, jellyfish, ctenophore, salps and pyrosomes (pelagic Tunicata), Cephalopods, and Amphipods.
  2. Macroplankton – Macroplankton measuring 2 to 20 cm, for example, Pteropods, Chaetognaths, Euphausiacea (krill), Medusa, ctenophore, salps, doliolids, and pyrosomes (pelagic Tunicata), Cephalopods, Janthinidae, and Amphipods.
  3. Mesoplankton – Mesoplankton measuring 0.2 to 20 mm. for example copepods, medusae, ostracodes, cladocera, chaetognaths, pteropods, heteropods, and tunicates.
  4. Microplankton – Microplankton measuring 20 to 200 meters. for example phytoplankton species, protozoa foraminifera, tintinnids, ciliates, rotifers, copepods nauplii.
  5. Nanoplankton – Nanoplankton measuring 2 to 20 µm. for example small diatoms, small flagellates, Pyrrophyta, Chrysophyta, Chlorophyta, and xanthophyll.
  6. Picoplankton – Picoplankton measuring 0.2 to 2 µm. for example most types of bacteria, as well as chrysophyte.
  7. Femtoplankton – Femtoplankton measuring less than 0.2 µm. For example, marine viruses.

Plankton can be found in all territorial waters on this earth, both in the ocean, sea, lake, and other types of waters. The variability of this species depends on several factors, such as:

  1. Availability of light, almost all of the growth plankton ecosystems are influenced by the availability of solar energy. For example, in waters that have low light availability, the growth of phytoplankton in the area will decrease.
  2. Availability of nutrients, although most areas in tropical and subtropical waters have an abundance of light, if the availability of nutrients such as phosphate, nitrate, and silicate is very low, this will affect the growth of plankton.
  3. Temperature changes also provide an important role in the growth of plankton, where the temperature of water in an area of ​​water can affect oxygen levels and the toxicity of the area. Plankton can develop optimally in waters that have temperatures between 25 to 30 ° C.
  4. The movement of water or water flow is an agent that helps supply food for the growth of plankton.
  5. Ph conditions or acidity levels of water that are too high can cause disruption of the physiological process of plankton.


Nekton is a type of organism that becomes an active swimmer in the waters, both freshwater and seawater. Nekton is often known as the top predator in most food chains in the sea. The word nekton comes from Greek which means swimming. Underlying the difference between nekton and plankton is that nekton has the ability to swim without having to rely on ocean currents. Nekton can be found in almost all regions and latitudes of marine waters. Fish are the largest nekton group, which is around 16,000 species. Nekton forms the basis of fisheries which is quite important on this earth.

Where nekton is a plankton predator that has various benefits for human life, such as improving nutrition and improving the economy. The carcasses of organisms belonging to nekton that accumulate on the seabed are the basic ingredients for the formation of marine minerals such as oil and gas.

In general, nekton has several characteristics, such as:

  1. Able to move or swim alone without relying on the help of water flow. He is also active in swimming.
  2. Is a consumer of the pelagic zone.
  3. Consists of invertebrate and vertebrate animals.
  4. Its lifespan is longer than plankton (vertebrate life span is 5 to 10 years, while invertebrates are around 1 year).
  5. Migrate related to the reproductive process.

Nekton consists of groups of vertebrate fish such as cucut fish, stingrays, marine reptile species, and several types of marine mammals.

Nekton classification

The first nekton classification is based on fish groups, nekton can be divided into 2 types, that is:


That is a group of fish that spend part of their lives in the epicenter of the sea, namely the area or sea zone which has a depth of 0 to 200 meters or about 656 feet. This group has a diversity of lifestyles such as:

Groups of organisms that spend adult time in epipelagic regions but are separated in coastal areas such as benign latitudes, commotion, haring.

Organisms that enter the epiphanic region only at certain times such as lantern fish groups that only appear on the surface at night to look for food.

Groups of organisms that spend their adult years in other regions, but they spend the beginning of their life cycle in the epicagic zone.

2. Holoepipelagik

That is a group of aquatic organisms that spend all their lives in the epicenter zone. Some of the species included in this group include hammerhead shark, mackerel shark, blue whale shark, tuna, flying fish, sawfish, setuthuk, lemuru, rowing fish, and so on.

Nekton is also classified according to its class, such as:

  1. Vertebrates are a nekton group consisting of vertebrate animals such as reptiles, mammals, and various types of fish.
  2. Molucca is a nekton group consisting of invertebrate animals that have soft bodies such as shells, squid, and octopus.
  3. Crustacea is a group of arthropods that have hard skin (shells) such as shrimp, crabs, lobsters, and so on.


Benthos is a type of organism that lives in the benthic zone, which is on the sea floor. Benthos is an organism that is abundantly sedimented on the surface of the continental shelf and in deeper waters. Because light cannot penetrate the benthic region, the organisms that live in the environment get energy from organic matter that descends from the higher zone. Or it can be said that the food chain of benthic organisms is supported by dead or decaying objects that float from the higher zones.

The main sources of food for benthic organisms are algae and organic runoff from the soil. Several factors such as temperature, salinity, water depth, and the types of local substrate that are very influential on the development of these benthic organisms.

Some types of organisms including benthos include protozoa, sponge, Coelenterate, Rotifera, Nematode, Bryozoa, Decapoda, Ostracoda, Cladocera, Copepoda, Pelecypoda, Gastropoda, Insecta, and Leeches. Other benthic organisms, such as starfish, oysters, clams, sea cucumbers, brittle stars, and sea anemones, have important roles, which is as a food source for fish and also for humans.

The roles of benthos organisms include:

  • Can help recycle organic ingredients
  • An important role in the food chain cycle
  • Can help the mineralization process
  • Because it has a long life cycle and limited movement, benthos organisms can be used as an indicator of pollution.

Benthos classification

Based on its size, benthos can be divided into 3 types, that is:


Macrobenthos consists of various types of benthic organisms that have a size greater than 1 mm so that the organism can still be seen by the eye. Examples of macrobenthos organisms include polychaete worms, bivalves, echinoderms, sea anemones, corals, sponges, lobsters, and cetaceans.

2. Meiobenthos

Consists of benthic organisms that have a small size that is less than 1 mm, but larger than 0.1 mm. These species belonging to meiobenthos are nematodes, foraminiferans, water bears, copepods and ostracodes.

3. Macrobenthos

Consists of benthic organisms that are less than 0.1 mm in size. Examples of microbenthos organisms include bacteria, diatoms, ciliates, amoeba, and flagellates.

While based on the type, benthos can be divided into:

  1. Zoobenthos consists of various types of animals that live in the benthic zone.
  2. Phytobenthos, consisting of various types of plants that exist in benthic zones, especially benthic diatoms and macroalgae (seaweed).
  3. Endobenthos is a benthic organism that has life buried in sediments especially in the upper oxygen layer area. Examples are sea pens or sand dollars.
  4. Epibenthos consists of benthic organisms that live on sediments such as sea cucumbers.
  5. Hyperbenthos consists of benthic organisms that live just above the sediments such as rock cod.

Efforts to Maintain Marine Biota

From the description above, we can know that there are so many types of marine biota where their presence plays a role in human life. However, now various problems are threatening the preservation of the marine biota, namely mass extinction. This occurs due to several factors such as a combination of high temperatures, acidification, and lack of oxygen.

Studies have shown that climate change and fishing that occur in an uncontrolled manner are also factors that cause the extinction of marine life. Then what are our efforts to keep marine biota sustainable?

  1. Preserve mangrove forests on the shores of the beach
  2. Prohibition of taking coral reefs which is a habitat for fish
  3. Prohibiting the use of explosives or other chemicals and the use of trawlers to catch fish
  4. Do not throw garbage or industrial waste into the sea

Hopefully, the explanation of this article is useful. Also, read other articles about biology:

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