Trophic Levels

Basic Food Chain

Basic Food Pyramid

Producers

• Also called autotrophs (as opposed to heterotrophs)
• Convert inorganic matter into organic molecules
• Plants, algae, and some bacteria

Primary Consumers

• Consume producers
• Herbivores
• Convert plant material into usable substances

Secondary Consumers

• Consume primary consumers
• Carnivores
• Cannot convert plant material

Tertiary Consumers

• Consume secondary consumers (although many may also consume primary consumers)
• Also carnivores
• ``Top predators''
• Cannot convert plant material
• Least efficient in terms of energy flow

Omnivores

• Both primary and secondary/tertiary consumers
• Can convert plant material
• Some can be consumed by tertiary consumers

Detritivores

• Consume detritus (i.e. inert organic matter)
• Can convert both plant and animal material
• Work in conjunction with decomposers

Decomposers

• Saprotrophs (and heterotrophs)
• Break down inert organic matter into forms that can be used again by producers
• Work in conjunction with (and are sometimes the same as) detritivores

Food Web

• Most organisms rely on multiple food choices
• More complex model
• More realistic model
• Energy still constrained to move in one direction
• Energy is dissipated as heat at each juncture

Simplified Temperate Forest Food Web

Arctic Marine Food Web