Ecosystems and Interrelationships Among Organisms

Meaning of an Ecosystem

An ecosystem is a community of living organisms (plants, animals and microorganisms) interacting with one another and with their non-living (physical) environment, such as soil, water, air and sunlight.

Components of an Ecosystem

• Biotic components – all living things: producers, consumers and decomposers
• Abiotic components – non-living factors: temperature, light, water, soil and air

Feeding Relationships

• Producers – green plants that make their own food through photosynthesis
• Consumers – organisms that feed on other organisms (herbivores, carnivores and omnivores)
• Decomposers – bacteria and fungi that break down dead organisms and waste, returning nutrients to the soil

Food Chains and Food Webs

A food chain shows a single, straight-line sequence of who eats whom (for example: grass → grasshopper → lizard → hawk). A food web is a more realistic network formed when several food chains overlap and interconnect in one habitat.

Types of Interrelationships

• Competition – organisms struggling for the same limited resource, such as food or space
• Predation – one organism (predator) hunting and feeding on another (prey)
• Symbiosis – a close relationship between two different species, which may benefit both (mutualism), benefit one without harming the other (commensalism), or benefit one while harming the other (parasitism)

Summary

Every organism in an ecosystem depends, directly or indirectly, on other organisms and on its physical surroundings, forming a balanced web of life that keeps the ecosystem stable.