Food Chains and Food Webs Notes

Food Chains and Food Webs

Food Chains

• A food chain is a model that illustrates a sequence of feeding relationships within an ecosystem.
• It links species together based on what they eat.
• A food chain specifically follows the connection between a single producer and a single chain of consumers.
• Example: Grama Grass → Desert Cottontail → Harris’s Hawk

Types of Consumers

• Herbivores: Consume only plants (e.g., rabbit).
• Carnivores: Consume only animals (e.g., lion).
• Omnivores: Consume both plants and animals (e.g., bear).
• Detritivores: Consume dead organic matter (e.g., earthworm).
• Decomposers: Detritivores that break down organic matter into simpler compounds (e.g., bacteria, fungi).

Specialists vs. Generalists

• Specialists: Consumers that primarily eat one specific organism or a very small number of organisms.
  • Example: Florida snail kites, which mainly feed on apple snails.
  • Changes in food web can cause extinctions.
• Generalists: Consumers that have a varying diet.
  • They can handle environmental changes more easily because they have alternative food sources.

Trophic Levels

• Trophic levels represent the nourishment levels in a food chain.

  • Producers (plants)
  • Primary Consumers: Herbivores that eat producers.
  • Secondary Consumers: Carnivores that eat herbivores.
  • Tertiary Consumers: Carnivores that eat secondary consumers.
  • Quaternary Consumers: Eat tertiary consumers.

• Heterotrophs

• Autotrophs

• Omnivores, such as humans, can occupy different trophic levels depending on the food chain.

Food Webs

• A food web is a complex network showing multiple feeding relationships within an ecosystem.
• Organisms can have multiple feeding relationships.
• Food webs emphasize the complicated relationships and energy flow within an ecosystem.