Ecology Basics
Ecology is the study of how living organisms interact with each other and with their environment.
Key Terms
- Population: all organisms of the same species in an area
- Community: all populations living together in an area
- Ecosystem: a community plus its abiotic (non-living) environment
- Habitat: the specific environment where an organism lives
- Niche: an organism's role in its ecosystem
Food Chains
A food chain shows the flow of energy from one organism to another through feeding relationships.
Example: Grass → Grasshopper → Lizard → Eagle
- Producers: plants (make their own food via photosynthesis)
- Primary consumers: herbivores (eat plants)
- Secondary consumers: carnivores (eat herbivores)
- Tertiary consumers: top predators
- Decomposers: bacteria and fungi (break down dead matter)
Food Web
A food web shows multiple interconnected food chains in an ecosystem. It is a more realistic picture because most organisms eat more than one type of food.
Energy Transfer
Only about 10% of energy passes from one trophic level to the next. The rest is lost as heat. This is why food chains rarely have more than 4–5 links.
💡 When a species is removed from a food web, it can cause a domino effect on other species — called a trophic cascade.