Food Web and Chain Notes

Definitions:
- Food Chain: Linear sequence of organisms where each is eaten by the next.
- Food Web: Interconnected network of multiple food chains, showing how energy and nutrients flow.
Main Differences:
- Food webs provide a more realistic representation of ecosystem relationships as they depict all possible feeding connections.

Levels:
- 1st Level: Primary Producers (e.g., grass, flowering plants)
- 2nd Level: Primary Consumers (e.g., grasshopper, rabbit)
- 3rd Level: Secondary Consumers (e.g., snakes, marten, humans)
- 4th Level: Tertiary Consumers (e.g., hawks, owls, eagles)
- 5th Level: Quaternary Consumers - often apex predators
Energy Pyramid:
- Energy decreases as it moves from producers to top predators.
- Generally limited to 4-5 trophic levels due to energy loss (approx. 90% lost as heat).

10% Rule: Approximately 10% of energy is transferred from one trophic level to the next.
Conservation of Energy: Energy is transformed or transferred, not created or destroyed.

Producers: Autotrophs (e.g., grass, flowers) that produce energy through photosynthesis.
Primary Consumers: Herbivores that consume producers (e.g., rabbits, grasshoppers).
Secondary Consumers: Carnivores/omnivores that consume primary consumers (e.g., snakes, wolves).

Organisms like fungi and bacteria that break down dead matter; often omitted from simple food webs, they play crucial energy recycling roles.

Removing species from food webs (e.g. red squirrels) affects the entire web, causing population changes in predators and other consumers.
Food webs are better models for energy flow than food chains due to their complexity.

To calculate available energy for secondary consumers:
- If producers have 2500 kcal, then secondary consumers receive:
- 2500 kcal * 0.10 (10%) = 250 kcal.
The apex predators like eagles have the least energy due to high energy loss at each trophic level.