Food Chains

Producers and consumers are roles in a food chain, which shows how energy flows through an ecosystem.

Producers:

• Definition: Organisms that make their own food using energy from the sun (photosynthesis) or chemicals (chemosynthesis).

• Type: Almost always plants, algae, or photosynthetic bacteria.

• Role: Start the food chain by producing biomass (stored energy).

• Example: Grass, phytoplankton.

Consumers:

• Definition: Organisms that cannot make their own food — they get energy by eating other organisms.

• Types:

  • Primary consumers – eat producers (e.g. rabbit eats grass).

  • Secondary consumers – eat primary consumers (e.g. snake eats rabbit).

  • Tertiary consumers – eat secondary consumers (e.g. eagle eats snake).

  • Apex predators – top of the chain, no natural predators (e.g. lion, killer whale).

Summary Table:

Key idea: Energy starts with producers and flows up through consumers.

• “top-down" control, where consumers in higher trophic levels affect organism abundance at lower trophic levels, or

• “bottom-up” control, where organism abundance at higher trophic levels is limited by nutrients or food availability at lower trophic levels.