What is Benthos? Types of Benthos and Their Role in the Aquatic Ecosystem

Definition of Benthos?

Benthos is the community of aquatic organism which lives in, above or near the bottom of lake, sea, river streams or any other aquatic environment. Light, temperature, pressure, salinity and depth of water all influence the diversity of the population of this community on a location.
These organisms lives in benthic zones in the ocean where the nature is very diversed. Naturally, sea floor have multitude types of habitats that species can anticipate to than the pelagic zone.
Some examples of Benthos are; clams, crabs, lobsters, sponges, sea stars, oysters, brittle star etc.

Composition/Types of Benthos:

Benthic Community is diversified from species including plants, animals and bacteria from diverse range of food chain. There are different types of Benthos, some of which hide in sediment throughout their life, some stay on sandy bottom, some are calm and logy, others wander throughout the seabed.
Based on the habitats Benthos ae 2 types:

Infauna: Burried in the bottom into the sediment.
Example;  worms and clams
Epifauna: Stay maybe by attaching to a hard surface like rocks, stones or live on the surface of bottom sediments
Example; Sponges, oysters, mussels, starfish
Benthos Can be divided into three categories based on their size:


Macrobenthos are comparatively large organisms living on or near in the bottom of water. Size varies from minimum 0.5 mm to normally more than 1 mm in length which can be located in naked eye. Another name of Macrobenthos is macrofauna.
Example: Seagrass, Echinoderms, sponges, crustaceans.


Meiobenthos are the organism that live in bottom of water of both freshwater and ocean water ecosystem. Size varies from 0.1 mm to upto 1.0 mm. Meiobenthos is also known as Meiofauna.
Example; Gastrotrich, water bears,


Microbenthos or microfauna is the community of species living in, on or near the bottom of marine water which are less than 1 mm in size. Microscope is required to see this microscopic organism.
Example; Amoeba, Flagella, Bacteria, diatoms
Based on the location Benthos are divided into three types:


Endobenthos make a hole or tunnel in the sediment and take place into it.
Example; sea pen or a sand dollar.


Epibenthos use top of the sediments as their habitats.
Example; sea cucumber or a sea snail


Hyperbenthos just live floating above the sediments.
Example; rock cod.

Role of Benthos in The Aquatic Ecosystem:

The Benthic organisms are most versatile on the coastal zone where the fish and other aquatic animals have multifaceted to a vast array of effects. Shallow maritime biological community is highly affected by the gathering of human and environmental changes. Benthic invertebrates functionally play big roles in fish production. Click Here to know how to find fish in the water.

Some important of Benthos is given bellow:

Essential Ecosystem:

Benthos plays a big role in ecosystem by decomposition. Dead organic matter is one of the main sources of energy for benthic species in shallow-water habitats. Benthic invertebrates inferential to produce 20– 73% of riverine leaf inputs to shallow water streams.


Benthic invertebrates release good amount of nutrients naturally by their feeding activities, excretion, and burrowing into sediments. Microbial plant is grown from this solution by the help of algae, bacteria and other aquatic angiosperm. The more benthic microbes increases, the more food source growth for fishes.


Benthos filter large amount of water and pump into their bodies. By this activity sediment and organic matters washed out that clean the water. The unused organic matter felled out on the bottom of the sea bed. That is called reminiralizaed matter. These reminaralized matters increase production rate of the ecosystem. This helps in high growth rate of fish production.

Food Source:

Many fishes feed on small to medium size benthic organism that live on sea floor. Vital saltwater fish community like haddock, catfish as well as many freshwater fish eats benthos.

Increase Oxygen:

Many of benthic animals move actively on the bottom and mix the sediments around there and improve the oxygen concentration which help in higher production overall organism.


Goedkoop and Johnson 1996, Lodge et al. 1998b, Stockley et al. 1998
Gunnarsson, K., Jónsson, G., & Pálsson, Ó. K. (1998). Sjávarnytjar við Ísland (Marine resources in Icelandic waters). Reykjavík: Mál og Menning, 280 pp. (in Icelandic)
Benthos (2008) Encyclopædia Britannica. (Retrieved May 15, 2008, from Encyclopædia Britannica Online.)


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