Lecture Notes: Understanding Food Chains and Food Webs

Introduction

Nature shows are a source of science education and often depict food chains in action.
Key idea: Food chains are part of nature's ecosystems, showing energy flow and predator-prey relationships.

Definition: A sequence showing who eats whom.
Components:
- Producer: An autotroph, e.g., plants, that make their own food.
- Primary Consumer: Heterotrophs, e.g., grasshoppers, that eat producers.
- Secondary Consumer: e.g., frogs, that eat primary consumers.
- Tertiary Consumer: e.g., snakes, that eat secondary consumers.
Energy Flow:
- Arrows point from food to consumer, indicating the direction of energy flow.
- Energy is reduced approximately 90% at each trophic level.
- Example: 10,000 kilocalories at producer level → 1,000 kilocalories at primary consumer → 100 kilocalories at secondary consumer.

Arranges food chains into trophic levels.
Trophic Levels:
- Trophic Level 1: Producers, highest energy.
- Trophic Level 2: Primary consumers, retain 10% of energy from producers.
- Further up, energy continues to decrease by 90%.

Removing one species (e.g., grasshoppers) affects others due to food scarcity.
Removing apex predators (e.g., snakes) can lead to overpopulation of secondary consumers (e.g., frogs).

Definition: Multiple interconnected food chains.
Benefits:
- Demonstrates biodiversity by showing interactions among various organisms.
- Provides resilience to ecosystems due to multiple feeding options for consumers.

Definition: Variety of organisms in an area.
Importance:
- Contributes to ecosystem sustainability.
- Allows ecosystems to recover from changes and disturbances.
- High biodiversity supports economic and ecological benefits.

Essential organisms, not typically shown in simple food chains/webs.
Include bacteria and fungi, which break down dead organisms.
All energy eventually cycles to decomposers, completing the ecosystem's energy flow.

Food webs, with their complexity, better represent real ecosystems compared to simple food chains.
Emphasizes the importance of biodiversity for resilient ecosystems.
Reminder: Continue being curious about nature and ecosystems.

Follow the Amoeba Sisters for more educational content on Twitter and Facebook!