Overview
This lecture explains the structure and roles within food chains and food webs, emphasizing producers, consumers, and decomposers in ecosystems.
Food Chains and Food Webs
- A food chain shows one organism consuming another for survival.
- A food web is a more accurate representation, displaying many interconnected food chains.
- All organisms play important roles in these systems.
Producers
- Producers are organisms at the start of the food chain, making their own food using sunlight through photosynthesis.
- Plants, vegetables, and photosynthetic protists are common producers.
- Producers supply energy and nutrients to other organisms.
Consumers
- Consumers eat other organisms and are organized into levels:
- Primary consumers (herbivores) eat only plants (e.g., elk, squirrel).
- Secondary consumers (carnivores) eat primary consumers (e.g., cats).
- Tertiary consumers eat secondary consumers (e.g., wolves).
- Omnivores (like humans and bears) eat both plants and animals and can be at various consumer levels.
Decomposers
- Decomposers feed on dead organisms and waste, breaking down nutrients.
- They recycle nutrients back into the soil for producers to use.
- Decomposers complete the ecosystem's nutrient cycle.
Key Terms & Definitions
- Food Chain — a sequence showing who eats whom in an ecosystem.
- Food Web — a complex network of interconnected food chains.
- Producer — an organism that makes its own food using sunlight (usually plants).
- Consumer — an organism that eats other living things for energy.
- Herbivore — a primary consumer that eats only plants.
- Carnivore — a secondary or higher-level consumer that eats animals.
- Omnivore — an organism that eats both plants and animals.
- Decomposer — an organism that breaks down dead material and returns nutrients to the soil.
- Photosynthesis — the process plants use to convert sunlight into food.
Action Items / Next Steps