Food Webs and Food Chains

Ecology

Objectives

• Identify different types of feeding relationships
• Define food chain and food web
• Identify organisms at different feeding levels
• Construct a food chain
• Identify food chains with at least 4 trophic levels from food webs

Feeding Relationships

• Producers:

  • Make their own food (autotrophs).
  • Trap energy from the sun.
  • Make food through photosynthesis.

• Examples of Producers:

  • Seaweed
  • Cyanobacteria
  • Phytoplankton
  • Plants

Feeding Relationships

• Consumers:
  • Obtain food from other organisms (heterotrophs).
  • Categories:
    • Herbivores
    • Carnivores
    • Omnivores
  • Decomposers

Feeding Relationships

• Herbivores:
  • Eat plants.

Feeding Relationships

• Carnivores:
  • Eat meat.
    • Predators are a type of carnivore; they hunt prey animals for food.
  • Scavengers feed on carrion (dead animals).

Feeding Relationships

• Omnivores:
  • Eat both plants and animals.

Feeding Relationships

• Decomposers:
  • Break down complex compounds of dead and decaying plants and animals into simpler molecules that can be absorbed.

Food Chain

• A simple diagram that shows how nutrients and energy flow from one organism to another.
• Example:
  • Algae and floating plants → Aquatic crustaceans → Fish → Raccoons

Trophic Levels

• Each link in a food chain is known as a trophic level.
• Trophic levels represent a feeding step in the transfer of energy and matter in an ecosystem.

Trophic Levels

Trophic Levels

• Producers: Autotrophs
• Primary consumers: Herbivores
• Secondary consumers: Small carnivores
• Tertiary consumers: Top carnivores

Food Web

• Shows all possible feeding relationships in a community at each trophic level.
• Represents a network of interconnected food chains.

Terrestrial Food Web

• Examples:
  • Grasses, Grains, Carrots → Grasshoppers, Mice, Rabbits → Birds, Owls, Foxes

Aquatic Food Web

• Examples:
  • Marsh Vegetation (sedges, grasses, bull rushes, algae, etc.) → Mosquito, Grasshopper, Rat, Vole, Snails → Herring, Salmon, Snow Geese → Bald Eagle, Harbour Seal, Marsh Hawk, Killer Whale