Biotic Components of Ecosystem

Living creatures make up the biotic elements or components of an ecosystem. They are made up of microbes, animals, and plants. Based on their connection to food, biotic components are categorized into three categories: producers, consumers, and decomposers.

1.   Producers

Producers are any living things capable of preparing food from inorganic ingredients. Thus, all green plants, photosynthetic bacteria, chemosynthetic bacteria, and all cyanobacteria are autotrophs (blue green algae).

            Solar energy is used by green plants, blue-green algae, and photosynthetic microorganisms to create chemical compounds. Although they also use CO2, chemosynthetic bacteria do not need light energy. They make use of chemical energy that is released during the oxidation of inorganic substances.

2.   Consumers

Since consumers are unable to create their own food, they must rely on other living things. Consumers are hence heterotrophs. There are three different categories of consumers.

  • Primary consumers

Primary consumers, or herbivores, are those organisms whose needs for food are entirely met by the producers. Examples include mice, zooplankton, insect larvae, and rabbits. 

  • Secondary consumers

Animals that rely on primary producers and consumers for their food are referred to be secondary consumers. They are either carnivores or omnivores, like insects, frogs, tiny fish, and predatory birds, among other things.

  • Tertiary consumers

They are apex carnivores that eat secondary consumers including tigers, lions, hawks, snakes, and other animals.

3.   Decomposers

Decomposers are saprophytic microbes that eat degraded and dead organisms for food. They transform organic molecules discovered in the creatures’ dead bodies into inorganic molecules. Saprophytic fungi and bacteria such as Bacillus, Clostridium, and Zygomonas are decomposers (species of Rhizobium, yeasts, Saprolegnia, etc.). On the deceased corpse, they release hydrolytic enzymes that break down complex organic compounds into their most basic forms. Decomposers take in externally digested food.

Biotic Interaction

A biotic community is made up of all the living things in an ecosystem. Animals that share a habitat have an indirect or direct effect on one another. Positive or negative interactions between living things, whether they are interspecific (between members of different species) or intraspecific, can occur (between the individuals of same species).

Positive interactions (Relationship of organisms in which both partners are benefited)

Inter-specific interaction:

 Each living thing aids the others in a biotic community, either a one-way or a reciprocal interaction One species may profit from or have no effect during a beneficial contact. Symbiosis, commensalism, and protocooperation are all examples of positive interaction.

Mutualism (Symbiosis): 

A biotic connection in which both individuals get something from the relationship is known as mutualism. They must be in a relationship since they can’t live on their own. Lichen, symbiotic bacteria, leguminous plants, mycorrhizae, etc. are a few examples. Fungi and algae make up lichen. Algae receive water, nutrients, and shelter from fungi. Algae provide nourishment for both themselves and the fungus. 

Rhizobium, a symbiotic bacterium that fixes nitrogen, is present in the root nodules of leguminous plants. Rhizobium feeds plants with nitrogen by fixing it in the atmosphere. Rhizobium finds refuge and sustenance in plants. 

A fungus and the root of higher plants have a symbiotic association, which is known as mycorrhiza. The root supplies nourishment and protection, whilst the fungus aids the plant in absorbing nitrate and phosphate.


It is the interaction between two organisms of different species where one species gain while the other neither loses nor gains anything. Examples include lianas, epiphytes, and more. 

Epiphytes are tiny plants that attach to larger ones. They flourish on bushes and trees. They do not eat or drink from other plants; they only use them as support. Rain, dust, and debris that have gathered in bark cracks serve as their source of hydration and nutrients. Orchids are a typical example of epiphytes. 

In tropical rain forests, lianas are present. Lianas ascent to the top of the canopy with the assistance of neighboring trees in search of greater lighting. The lianas Bauhinia, Ficus, and Tinospora are examples.


It is a sort of interaction between two organisms of various species in which both benefits, however a relationship is not required. They are capable of living on their own. 

Predatory birds that feed on ectoparasites like leeches and lice sit on cattle as an example of protocooperation. While cattle are protected from ectoparasites, birds receive nourishment. 

The interaction between the hermit crab (Eupagunes predeauxi) and the sea anemone (Adamsia pallicata) is seen as a kind of protocooperation. While the sea anemone is stationary, the hermit crab is free to swim. By being associated with hermit crab, sea anemone gains access to more food, and vice versa. This interaction is viewed as commensalism by some ecologists.

Intraspecific interaction

  1. Colonization: It is the gathering of members of the same species for purposes of food, improved protection from predators, or severe environmental circumstances. Microorganisms including Nostoc, Obelia, Volvox, Anabaena, and others frequently colonize new areas.
  2. Social organization: It is a group of individuals who belong to the same species where there is work division for the benefit of society. Ants, wasps, bees, and other well-known examples of social organization can be found.
  3. Aggregation: It is another kind of clustering together of the same kind of organisms. Numerous autonomous individuals congregate at one place. As seen in a swarm of locusts, grasshoppers, schools of fish, etc., aggregation is advantageous when there is a lack of food, available space, or light, as well as for reproduction.

Negative interaction (Relation of organisms in which one organism is benefited and another is harmed)

Parasitism: It is a relationship between two distinct species of animals in which the smaller creature (the parasite) feeds on the bigger organism (the host) without really killing it. Parasites reside in or on the host’s body. The parasite may thus be divided into two groups: ectoparasites and endoparasites. Leech, lice, bugs, and other ectoparasites sucking blood or plant juice (like aphids). Disease is caused by endoparasites (Ascaris, Taenia, Fasciola).

Predation: When a bigger organism (a predator) captures, kills, and consumes a smaller organism (prey), there is a connection between the two animals of different species (prey). Predators are frequently carnivorous creatures, such as lions that hunt deer, frogs that consume insects, and hawks who consume rabbits and snakes.

Antibiosis: There is a relationship between two organisms of different species when a larger organism (a predator) catches, kills, and eats a smaller organism (prey). Carnivorous animals such as lions who hunt deer, frogs that eat insects, and hawks that devour bunnies and snakes are examples of predators.

In the microbiological world, antibiosis is frequent. Another microbe is inhibited or killed by an antibiotic that one microorganism produces. Staphylococcus cannot grow in the presence of penicillium. Higher plants exhibit antibiosis. Nematodes cannot survive in close proximity to marigold plants. Weeds cannot thrive on some crops, including barley, rye, sorghum, millet, soyabean, and sunflower. Similar to how Eupatorium prevents numerous plants and shrubs from growing in woods.

What are autotrophs?

The term “autotroph” refers to creatures that can synthesize their own food through either photosynthesis or chemosynthesis. They don’t require other species to provide them with energy because they are self-sufficient in terms of nutrition. 

Autotrophs use photosynthesis to transform light energy into chemical energy, which they then store in organic molecules like glucose. The chloroplasts of plants, algae, and certain bacteria are where this process takes place. Chlorophyll is used in this process. 

On the other hand, chemosynthetic autotrophs utilize the energy from chemical processes to create organic substances. Some bacteria that live in harsh conditions, such deep-sea vents and hot springs, where sunlight is not accessible, exhibit this sort of autotrophy.

What are heterotrophs?

Heterotrophs are creatures that depend on other sources of food since they are unable to make it themselves. Heterotrophs must devour other species in order to receive energy and nutrients since, in contrast to autotrophs, they are unable to synthesis their own organic components from inorganic materials. 

Heterotrophs come in two primary categories: consumers and decomposers. Consumers, like animals and fungi, consume plants or engage in scavenging to obtain food from other creatures. Dead organic waste is broken down by decomposers like bacteria and fungus, which recycle nutrients back into the environment.

What are parasites?

Organisms known as parasites ingest nutrients from their hosts, which they inhabit or live on, in order to survive. In practically every type of life, including animals, plants, and even microbes, parasites are present. 

There are many different kinds of parasites, such as ectoparasites, which exist on the host’s outside, and endoparasites, which exist within. Ticks, lice, and fleas are some instances of ectoparasites, whereas tapeworms, roundworms, and some types of protozoa are examples of endoparasites. 

Depending on the degree of the illness, parasitism can have a substantial impact on the wellbeing and survival of the host organism. The host may occasionally be able to tolerate the parasite’s presence and go on as normal, in other instances, the infection may cause critical health issues or even death. 

It’s crucial to remember, though, that not all parasites are detrimental to their hosts. In fact, some parasites have beneficial relationships with their hosts known as symbiotic relationships, in which both the host and the parasite gain from the association.

Define individual.

A single creature, organism, or living thing that is different and unique from others of its sort is referred to as an individual. A single unit of life that is self-contained and capable of operating independently is referred to as an individual and can include a person, animal, plant, or single-celled creature. 

A living organism’s distinct physical and physiological traits, as well as its behavior and interactions with its environment, are collectively referred to as an individual in biology. Understanding the qualities and characteristics of individual animals may offer valuable insights into more general patterns and processes, which makes the idea of the individual significant in many domains, including genetics, ecology, evolution, and medicine.

What is an ecosystem?

A complex web of interactions between living things and their natural surroundings makes up an ecosystem. It is a dynamic community made up of living things like plants, animals, microbes, and other creatures, as well as the nonliving elements of their surroundings including air, water, soil, and sunshine. 

A forest or pond are examples of tiny, localized ecosystems. A biosphere is an example of a bigger, more complex ecosystem. In an ecosystem, organisms engage in a range of interactions with one another and the physical environment, such as competition, predation, mutualism, and decomposition. These interactions produce a web of connections that governs the quantity and distribution of many species as well as the ecosystem’s general health.

Binod G C

I'm Binod G C (MSc), a PhD candidate in cell and molecular biology who works as a biology educator and enjoys scientific blogging. My proclivity for blogging is intended to make notes and study materials more accessible to students.

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