Organisation of Ecosystems

There are four levels of organisation in an ecosystem:

  • Organism
  • Population
  • Community
  • Ecosystem

The "COMPONENTS OF THE ECOSYSTEM" in a divided panel format. On the far left under "ORGANISM", there is a single illustrated fish. Next, in the "POPULATION" section, there's a group of identical fish swimming together. In the "COMMUNITY" column, various marine life, including a jellyfish, a group of fish, and a larger fish, are depicted coexisting. Lastly, in the "ECOSYSTEM" section, the scene is more comprehensive, showing a jellyfish, fish, a big whale-like creature, and snails at the seabed, all within a water column with tiny bubbles and a sandy bottom. The colours are predominantly soft blues, capturing an aquatic theme.

Components of the Ecosystem


A species is a group of similar organisms that are able to breed together and produce fertile offspring. This includes every plant and animal species that can be found on Earth.


A population consists of individuals of the same species that live in a specific area at the same time.

  • The interaction of many different populations within the same habitat creates a community.


A community is a group of populations belonging to two or more species that are living and interacting with each other in the same area. Each species in a community depends on another species for factors that are essential for their survival and reproduction (e.g. food, shelter etc). So, if you remove one species, it can affect the whole community.

  • In a stable community, the populations of all the species remain relatively constant over time


An ecosystem is a biological community of organisms that interact with each other and their physical environment. Ecosystems include all the abiotic and biotic components that live and interact within the same environment.

  • Abiotic components/factors – Non-living factors which can affect the size and distribution of populations (e.g. temperature, air currents, water and minerals).
  • Biotic components/factors – Living factors which can affect the size and distribution of populations (e.g. plants, animals, and microorganisms).


An adaptation is a characteristic that helps an organism to survive and reproduce in its environment. Organisms can evolve over time to become better adapted to their environment.


Many organisms require the same resources. Due to a limited supply, they compete for these resources.

There can be competition between the same species or competition between different species.

  • Animals – may compete for food (for energy), water, space (to live in) and mating partners (to produce offspring and pass on characteristics).
  • Plants – may compete for light (for photosynthesis), water (for photosynthesis), space (to grow in) and mineral ions (for growth).