What do the solid arrows represent? What do the dashed arrows represent? Can you trace a food chain from one of the producers to the bobcat? Why is a food web a more accurate representation of feeding relationships in an ecosystem than a food chain? Even though only one organism is shown in the food web, it represents all the individuals of the species.

Ecological Pyramids Shows the relative amount of energy contained within each trophic level in a food chain

Trophic Levels Trophic – Greek “trophe” Producers= 1st trophic level Food or nourishment Producers= 1st trophic level Consumers= 2nd level and higher

Trophic Levels Read from the bottom to the top of pyramid 1st trophic level- producers/autotrophs Ex: Plants 2nd trophic level- primary consumers Ex: Herbivores or omnivores 3rd trophic level- secondary consumers Carnivores or omnivores 4th + trophic levels- tertiary or quad consumers Ex: top predators- carnivores

Types of Pyramids “The 10% Rule” 1. Energy Pyramids 10% energy transferred up to next level as organisms feed on one another. The rest is lost as HEAT. “The 10% Rule”

Types of Pyramids 2. Biomass Pyramids Biomass – total amount of organic matter present in a trophic level

Number of organisms at each trophic level. Higher # at LOWER levels. Types of Pyramids 3. Pyramid of numbers Number of organisms at each trophic level. Higher # at LOWER levels. http://www.harcourtschool.com/activity/science_up_close/314/deploy/interface.html