Food webs: real ecosystems

Real ecosystems are more complex than simple food chains.

A food web shows how organisms are linked through multiple feeding relationships.

• Most organisms eat more than one species
• Energy can move through several pathways
• Food webs increase ecosystem stability

More connections = greater resilience if one species disappears.

Why food chains are short

Food chains rarely have more than four or five trophic levels.

This is because energy decreases at each step up the food chain.

• Less energy available at higher levels
• Top predators need large territories
• Ecosystems cannot support many high-level consumers

Short food chains are a direct result of energy loss at each transfer.