What is an Ecosystem? Structure, Types, Importance and Function of Ecosystem

An ecosystem, a term very often used in biology, is a community of plants and animals interacting with each other in a given area and also with their non-living environments. The non-living environments include weather, earth, sun, soil, climate, and atmosphere.

The ecosystem relates to the way that all these different organisms live in close proximity to each other and how they interact with each other.

For instance, in an ecosystem where there are both rabbits and foxes, these two creatures are in a relationship where the fox eats the rabbit to survive. This relationship has a knock-on effect on the other creatures and plants that live in the same or similar areas. In other words, the more rabbits that foxes eat, the more the plants may start to thrive because there are fewer rabbits to eat them.

According to Wikipedia,

“An ecosystem is a community of living organisms in conjunction with the nonliving components of their environment (things like air, water, and mineral soil), interacting as a system. These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows.

As ecosystems are defined by the network of interactions among organisms, and between organisms and their environment, they can be of any size but usually encompass specific, limited spaces (although some scientists say that the entire planet is an ecosystem).”

Ecosystems can be huge, with many hundreds of different animals and plants all living in a delicate balance, or they could be relatively small.

In particularly harsh places in the world, such as the North and South Poles, the ecosystems are relatively simple because only a few types of creatures can withstand freezing temperatures and harsh living conditions.

It’s also worth noting that some creatures can be found in multiple different ecosystems all over the world in different relationships with other or similar creatures. So basically, ecosystems also consist of creatures that mutually benefit from each other.

For instance, a popular example is that of the clownfish and the anemone – the clownfish cleans the anemone and keeps it safe from parasites as it stings bigger predators that would otherwise eat clownfish.

Earth as an ecosystem stands out in the all of the universe. There’s no place that we know about that can support life as we know it, not even our sister planet, Mars, where we might set up housekeeping someday, but at great effort and trouble we have to recreate the things we take for granted here.

~ Sylvia Earle

An ecosystem can be destroyed by a stranger. The stranger could come in the form of an increase in temperature, a rise in sea level, or climate change. Either of these factors can affect the natural balance and harm or destroy the ecosystem.

It’s a bit unfortunate but ecosystems have been destroyed and vanished by man-made activities like deforestation, urbanization, and natural activities like floods, storms, fires, or volcanic eruptions.

Ecosystem Structure

Each ecosystem has two main components:

1. Abiotic Components

The non-living factors or the physical environment prevailing in an ecosystem form the abiotic components.

They can be grouped into two:

  • Climatic Factors: They include rain, temperature, light, wind, humidity, etc., and
  • Edaphic Factors: These include soil, pH, topography minerals, etc.

2. Biotic Components

These comprise living organisms such as plants, animals, and micro-organisms (Bacteria and Fungi) present in an ecosystem form the biotic components.

The biotic components can be further grouped into two basic components from the nutrition point of view:

(i) Autotrophic Components – They include all green plants that fix the sun’s radiant energy and manufacture food from inorganic substances.

(ii) Heterotrophic Components –They encompass non-green plants and all animals that take food from autotrophs.

Therefore, biotic components can be described under the following heads: producers, consumers, and decomposers.



Among biotic components, at a basic functional level, an ecosystem generally contains primary producers (plants) capable of harvesting sun energy through photosynthesis. This energy then flows through the food chain.


Primary consumers

After producers, next come consumers in the ecosystem. There are different classes or categories of consumers; these consumers feed on the captured energy.

  • First Order or Primary Consumers: These are basically herbivores, animals that depend purely on producers or green plants for their food. Insects, rodents, rabbits, deer, cows, buffaloes, and goats are some of the common herbivores in the terrestrial ecosystem, and small crustaceans, mollusks, etc. in the aquatic habitat.
  • Second Order or Secondary Consumers – These encompass carnivores, flesh-eating animals, and omnivores, animals adapted to consume herbivores and plants as their food. Secondary consumers are sparrows, crows, foxes, wolves, dogs, cats, snakes, etc.
  • Third Order or Tertiary Consumers – These are the top carnivores that prey upon other carnivores, omnivores, and herbivores. Lions, tigers, hawks, vultures, etc., are tertiary or top consumers.
  • Parasites, Scavengers, and Saprobes – They are also included in the consumers that utilize living tissues or dead remains of animals and plants as their food.


Decomposers work at the bottom of the food chain. Dead tissues and waste products are produced at all levels. Scavengers, detritivores (animals that live on the detritus of ecosystems), and decomposers not only feed on this energy but also break organic matter back into its organic constituents.

The energy that flows through the food chain, i.e., from producers to consumers to decomposers, is always inefficient, moving from a lower level in the food chain to the immediate level above it. That means less energy is available at the secondary consumer level than at the primary producer level.

It’s not surprising, but the amount of energy produced from place to place varies greatly due to the amount of solar radiation and the availability of nutrients and water.

Types of Ecosystem

There are many types of ecosystems out there, but the three major classes of ecosystems, sometimes referred to as ‘biomes’, which are relatively contained, are the following:

  • Freshwater Ecosystems
  • Terrestrial Ecosystems
  • Ocean Ecosystems

Freshwater Ecosystems

Freshwater ecosystems

These can be broken up into smaller ecosystems. For instance, in the freshwater ecosystems, we find:

  • Pond Ecosystems – These are usually relatively small and contained. Most of the time, they include various types of plants, amphibians, and insects. Sometimes, they include fish, but as these cannot move around as easily as amphibians and insects, it is less likely, and most of the time, fish are artificially introduced to these environments by humans.
  • River Ecosystems – Because rivers always link to the sea, they are more likely to contain fish alongside the usual plants, amphibians, and insects.

Freshwater ecosystems can also include birds because birds often hunt in and around water for small fish or insects.

As is clear from the title, freshwater ecosystems are those that are contained in freshwater environments. This includes but is not limited to, ponds, rivers, and other waterways that are not the sea (which is, of course, saltwater and cannot support freshwater creatures for very long).

Freshwater ecosystems are the smallest of the three major classes of ecosystems, accounting for just 1.8% of the Earth’s surface.

The ecosystems of freshwater systems include relatively small fish (bigger fish are usually found in the sea), amphibians (such as frogs, toads, and newts), insects of various sorts, and plants.

The absolutely smallest living part of the food web of these sorts of ecosystems is plankton, a small organism that is often eaten by fish and other small creatures.

Terrestrial Ecosystems

Terrestrial ecosystem

Terrestrial ecosystems are many because there are so many different places on Earth. Some of the most common terrestrial ecosystems that are found are the following:

  • Rainforests – Rainforests usually have extremely dense ecosystems because there are so many different types of animals living in a very small area.
  • Tundra – As mentioned above, tundra usually have relatively simple ecosystems because of the limited amount of life that can be supported in these harsh conditions.
  • Deserts – Quite the opposite of tundra in many ways, but still harsh, more animals live in the extreme heat than in the extreme cold of Antarctica, for instance.
  • Savannas – These differ from deserts because of the rain they get each year. Whereas deserts get only a tiny amount of precipitation every year. Savannas tend to be a bit wetter, which is better for supporting more life.
  • Forests – There are many different types of forests all over the world, including deciduous forests and coniferous forests. These can support a lot of life and can have very complex ecosystems.
  • Grasslands – Grasslands support a wide variety of life and can have very complex and involved ecosystems.

Because terrestrial ecosystems are so diverse, it is difficult to generalize them. However, a few things are true almost all of the time. For instance, most contain herbivores that eat plants (that get their sustenance from the sun and the soil), and all have carnivores that eat herbivores and other carnivores.

Some places, such as the poles, contain mainly carnivores because no plant life grows. A lot of animals and plants that grow and live in terrestrial ecosystems also interact with freshwater and sometimes even ocean ecosystems.

Ocean Ecosystems

Ocean ecosystems

Ocean ecosystems are relatively contained, although they, like freshwater ecosystems, also include certain birds that hunt for fish and insects near the ocean’s surface.

There are different sorts of ocean ecosystems:

  • Shallow Water – Some tiny fish and coral only live in the shallow waters close to land.
  • Deep Water – Big and even gigantic creatures can live deep in the oceans. Some of the strangest creatures in the world live right at the bottom of the sea.
  • Warm Water – Warmer waters, such as those of the Pacific Ocean, contain some of the most impressive and intricate ecosystems in the world.
  • Cold Water – Less diverse, cold waters still support relatively complex ecosystems. Plankton usually forms the base of the food chain, followed by small fish that are either eaten by bigger fish or by other creatures such as seals or penguins.

Ocean ecosystems are amongst some of the most interesting in the world, especially in warm waters such as those of the Pacific Ocean. A key factor is that about 75% of our planet is enveloped by the sea, providing ample room for diverse creatures to inhabit and prosper.

There are actually three different types of oceanic ecosystems: shallow waters, deep waters, and the deep ocean surface. In two of these, the very base of the food chain is plankton, just as it is in freshwater ecosystems. These plankton and other plants that grow in the ocean close to the surface are responsible for 40% of all photosynthesis that occurs on Earth.

Some herbivores, such as shrimp, eat the plankton. They are then usually eaten by bigger creatures, particularly fish.

Interestingly, plankton cannot exist in the deep ocean because photosynthesis cannot occur since light cannot penetrate that far into the ocean’s depths.

In the deepest depths of the ocean, therefore, creatures have adapted very strangely and are among some of Earth’s most fascinating, terrifying, and intriguing living creatures.

Water birds and ecosystem

Importance of Ecosystem

Ecosystems are communities of organisms and non-living matter that interact together. As ecosystems are interdependent, each part of the ecosystem is important. Damaged or imbalanced ecosystems can cause many problems.


Ecosystems comprise soil, sunlight and heat, water, and living organisms, including plants, animals, and decomposers.

Interactions Between Components

Within an ecosystem, living organisms interact in different ways, including predation, cooperation, competition, and symbiosis. Each species has a special role, such as converting sunlight to energy through photosynthesis, eating small insects, or decomposing matter.

Size of Ecosystem

The sizes of the ecosystems vary widely. They can be a puddle, a lake or a desert. Terrariums are artificial ecosystems.


Biomes are composed of several ecosystems that are similar to each other. Biomes include tropical rainforests, deserts, tundra, and grasslands.

Disturbances in Ecosystem

A small change in an ecosystem, such as eliminating or introducing one species, can cause changes in the entire ecosystem. Environmental changes, as well as human interference, can cause these disturbances in the ecosystem.

Impact of Pollution

Pollution, including land, water, and air pollution, poses a serious threat to ecosystems. Pollution can threaten or kill organisms vital for ecosystems, and the ecosystem can become imbalanced.

Function of Ecosystem

An ecosystem is a discrete structural, functional, and life-sustaining environmental system.

Ecosystem functions

The functional components in any ecosystem are:

(i) Inorganic constituents (air, water, and mineral salts)

(ii) Organisms (plants, animals, and microbes), and

(iii) Energy which other components receive from outside (the sun).

These three form an environmental system and interact with each other. Inorganic constituents are synthesized into organic structures by green plants (primary producers) through photosynthesis utilizing solar energy.

Green plants become the energy source for renewals (herbivores), which, in turn, become a source of energy for flesh-eating animals (carnivores).

All types of animals grow by adding organic matter to their body weight, and complex organic compounds taken as food are their energy source. They are known as secondary producers.

All the living organisms in an ecosystem have a definite life span, after which they die. The dead organic remains of plants and animals provide food for saprophytic microbes like bacteria, fungi, and many other animals. The saprobes finally decompose the organic structure, break the complex molecules, and liberate the inorganic components into the environment.

These organisms are known as decomposers. During the decomposition process of organic molecules, the energy which binds the inorganic components together in the form of organic molecules gets liberated and dissipated into the environment in the form of heat energy.

Thus, in ecosystem energy from the sun, the input is fixed by plants and transferred to animal components. Nutrients are withdrawn from the substrate, deposited in the tissues of the plants and animals, cycled from one feeding group to another, released by decomposition to the soil, water, and air, and then recycled.

The ecosystems operating in different locations, such as deserts, forests, grasslands, and seas, are interdependent. The energy and nutrients of one ecosystem may find their way into another so that, ultimately, all parts of the earth are interrelated, each comprising a part of the total system that keeps the biosphere functioning.


Ecosystem – Encyclopedia of Earth

Ecosystems – Encyclopedia

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About Rinkesh

A true environmentalist by heart ❤️. Founded Conserve Energy Future with the sole motto of providing helpful information related to our rapidly depleting environment. Unless you strongly believe in Elon Musk‘s idea of making Mars as another habitable planet, do remember that there really is no 'Planet B' in this whole universe.