Biotic factors are defined as the living components of an ecosystem. The biotic factors ranging from bacteria reside in the human intestine to animals and plants. Several disease-causing agents such as viruses, bacteria are also biotic factors that affect the ecosystem.

What are Biotic Factors?

The living components of any ecosystem are called biotic factors or biotic components. The term “biotic” means “related to living organisms”. All living organisms and the physiochemical components combine called an ecosystem.

The ecosystem is made of two factors named- biotic and abiotic factors. All living organisms are called biotic factors, and physiochemical components are abiotic factors. These two factors interact and function together in any ecosystem.

The physical factors such as sunlight, water, temperature, other chemical factors, and non-living components are the abiotic factors. The living organisms are called biotic factors such as bacteria, birds, animals, plants, and other living things.

Role of Biotic Factors in an Ecosystem

An environment has shaped by its components and interaction between animals in an ecosystem. For example, a water body (river, sea) consists of biotic factors such as fish, algae, amphibians, and aquatic plants. The biotic factors are affected by the abiotic factors or physical components such as temperature, water and create a unique ecosystem.

The proper functioning of biotic factors requires a certain amount of energy, food, and environment. To complete their energy needs they depend upon other biotic factors. For example, a deer feed upon a plant, and the deer itself is a predator for carnivores.

Plants are the only biotic factors that do not depend upon other biotic factors for their energy needs. They perform photosynthesis are producing their own food in the presence of sunlight. However, some carnivorous plants also occur that capture insect or other animals to obtain their food. E.g. Venus flytrap.

Despite the fact, these carnivorous plants are also able to perform photosynthesis and make their own food. Therefore they are called producers in an ecosystem. The habitat of other organisms also depends on an abundance of plants. However, some ecosystems such as deep oceans, deserts, and lava beds do not have an abundance of plants.

Types of Biotic Factor

The effect of certain biotic factors on other biotic factors on the ecosystem depends on the type of the biotic factor. Based on the roles in an ecosystem, the biotic factors are divided into three types.

i. Producers

ii. Consumers

iii. Decomposers

i. Producers

The producers can produce food by inorganic materials and energy sources (e.g. sunlight). They are very important in every ecosystem because life may not exist without producers. The complex organic compounds such as carbohydrates, protein, and fat are produced by the producers by using CO2 and water.

They use two different mechanisms to convert the inorganic components into organic compounds that are photosynthesis and chemosynthesis. Therefore the producers are classified into two major classes:

a. Photoautotrophs

b. Chemoautotrophs

a. Photoautotrophs

The producers that get their energy from sunlight to perform photosynthesis are called photoautotrophs. For example- plants, algae, are the most common producers on the earth. A pigment named chlorophyll is used to harness the photons in sunlight.

The energy derived in this process is stored in the form of complex organic molecules such as carbohydrates, protein. These compounds are consumed by other heterotrophic animals. The organisms that depend directly on plants for their nutrition are called herbivores.

However carnivorous animals do not directly consume plant parts, they depend upon herbivores. There are some photoautotrophic bacteria that also occur. Cyanobacteria or blue-green algae are common examples of photoautotrophic bacteria. They are ubiquitous organisms and are found in soil, freshwater, and seawater.

b. Chemoautotrophs

The organisms that have the ability to synthesize food through the process of chemosynthesis are called chemoautotrophs. Chemotrophs are divided into two types- chemoautotrophs and chemoheterotrophs. Chemoheterotrops are chemotrophs that cannot fix carbon to organic compounds.

They use hydrogen sulfide, sulfur, ammonium, etc. as energy sources. Examples of chemoautotrophs include methanogens that produce methane. In the environment, the process is based on the oxidation of electron donors.

The chemoautotrophs are divided into several classes- thermoacidophiles, methanogens, anammox bacteria, sulfur reducers, and oxidizers. The example of chemoheterotrophs is iron and manganese-oxidizing bacteria.

The main difference between chemoautotrophs and photoautotrophs is the need for light for food production. Chemoautotrophs produce food in absence of light whereas photoautotrophs use sunlight.

ii. Consumers

The organisms that depend on other organisms for their energy needs are called consumer biotic factors. They are also known as heterotrophs. The word heterotroph is made up of two Greek words hetero +trophs. The word “hetero” meaning “others” and “trophic” means “food”. Heterotrophic organisms are not able to perform photosynthesis thus they depend on other organisms for nutrition.

Humans are also heterotrophic organisms. We cannot make organic compounds and get this nutrition from plants and animals. All the animals, bacteria, fungi, and parasitic plants are called consumers. The consumers are divided into primary, secondary, and tertiary consumers. The first level is primary consumers that eat plants.

They are herbivorous animals such as rabbits, deer, etc. The secondary consumers get their nutrition from primary consumers and that are carnivorous animals. The tertiary consumers are also called top carnivores or omnivores. They may eat herbivorous and secondary consumers.

Deciduous Forest: Definition, Examples, and Facts

For example, a rabbit gets energy from grass, and snake eats the rabbit, and an owl eats snakes. Here the rabbit is the primary consumer, a snake is a secondary consumer, and an owl is a tertiary consumer respectively.

Another classification of heterotrophs are lithotrophs that depend upon non-organic sources of food and organotrophic that use organic compounds. Most heterotrophs use different mechanisms such as fermentation, aerobic respiration, and anaerobic respiration to digest the organic compounds.

They use ATP as an energy molecule and convert sugar into ATP. In mammals, the ATP is produced by the process of cellular respiration followed by oxidative- phosphorylation.

iii. Decomposers

The organisms that decompose the dead organic material of the ecosystem are called decomposers. They break down the dead organic material into simpler molecules and get nutrients from it. The process initiates by detritivores that can be vertebrates, invertebrates, and some plants.

Decomposers play an important role in an ecosystem by recycling nutrients. Examples of detritivores are fungi, bacteria, flies, worms, etc. Some arthropods are also capable to break down the chunks of organic matter into simpler compounds and provide space for bacteria to work on it. Millipedes, slugs, springtails, and sea stars are also some common examples of detritivores.

Detritivores differ from consumers in their mode of nutrition. They get energy from dead organic material whereas consumers get their nutrition from alive organisms. The metabolism of rotting animals and fruits can only be done by detritivores.

The decomposers can be classified into two types- macro-detritivores that are larger in size and micro-detritivores that are smaller organisms such as bacteria.

Biotic Factors Example

Some common examples of producers are plants and trees. They perform photosynthesis and produce organic compounds. Some coral, algae, and bacteria are also primary producers of an ecosystem. They are also an important part of the food chain. Cyanobacteria are also another example of photosynthetic organisms. They are also believed to be evolved from the earliest prokaryotes. Heterotrophic animals such as rabbits, tigers, zebra, elephants, fishes, aquatic animals, birds, and amphibians are also examples of biotic factors. The diversity and balance among biotic and abiotic factors of an ecosystem can be disturbed by various human disturbances.

Biotic Factor Citations

• Environmental abiotic and biotic factors affecting the distribution and abundance of Naegleria fowleri. FEMS Microbiol Ecol . 2020 Dec 30;97(1):fiaa238.
• The Threat of the Combined Effect of Biotic and Abiotic Stress Factors in Forestry Under a Changing Climate. Front Plant Sci . 2020 Nov 30;11:601009.