Trophic Levels

Definition

• Trophic levels: Different levels in a food chain.
  • Example food chain:
    • Grass: Trophic level 1
    • Rabbit: Trophic level 2
    • Snake: Trophic level 3
    • Hawk: Trophic level 4

Trophic Level Breakdown

1. Producers (Trophic Level 1)

   • Typically plants or algae.
   • Use photosynthesis to produce food using sunlight.
   • Source of all energy in the food chain.

2. Primary Consumers (Trophic Level 2)

   • First consumers in the food chain.
   • Also called herbivores, they consume plants and algae.

3. Secondary Consumers (Trophic Level 3)

   • Second level of consumers.
   • Known as carnivores, they consume other animals.

4. Tertiary Consumers (Trophic Level 4)

   • Third level of consumers.
   • Also carnivores.

Energy Transfer Between Trophic Levels

• Usually, food chains have no more than 4 or 5 trophic levels.
• Energy loss occurs as one moves up each level.
• Only ~10% of energy transfers to the next trophic level.
  • Example Energy Flow:
    • 1,000 joules at level 1 → 100 joules at level 2 → 10 joules at level 3 → 1 joule at level 4.

Apex Predators

• Carnivores at the top of the food chain.
• Have no predators.

Omnivores

• Eat both producers and animals.
• Typically placed in trophic level 3.

Decomposers and Detritivores

• Include organisms like bacteria, fungi, and worms.
• Decompose dead matter to recycle nutrients back to the ground for use by producers.

Conclusion

• Understanding trophic levels helps explain energy flow and ecosystem dynamics.
• Omnivores and decomposers are special cases in the trophic system.