Food Webs and Pyramids

Feeding Interactions Terms Autotroph(Producers) - Plants, produce energy from the sun. How? Heterotroph(Consumers) - obtain energy from consuming (eating) Herbivores - consumers that only eat plants Predators - eat other animals Carnivores - meat only Omnivores - meat and plants Decomposers – organisms that obtain energy from dead organic material, return organic material to the abiotic ecosystem Bacteria Fungi, slime molds Photosynthesis

Food Chain Shows energy movement through a single feeding interaction in an Ecosystem. Arrows represent energy movement Grass Grasshopper Frog Snake Red tailed Hawk Primary Consumer Top-level Consumer Producer Secondary Consumer Tertiary Consumer Herbivore Predator Predator Predator

Food Web Shows all the feeding relationships in an community. Arrows show the movement of energy

Trophic Levels Trophic levels in a food chain Grass Grasshopper Frog Snake Red tailed Hawk Primary Consumer Top-level Consumer Producer Secondary Consumer Tertiary Consumer Trophic levels in a food chain Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer, Top-level Consumer -or- Producer, 1st level consumer, 2nd level consumer, 3rd level consumer, top-level consumer

Trophic Levels – Food Web Organisms can play multiple roles in an ecosystem Ex. The Bat is both a primary consumer and a secondary consumer

What is Biomass? Total dry mass of all the living material in an ecosystem. Used to quantify the biotic components of an ecosystem

Ecological Pyramids Diagrams that display a feeding relationship in an ecosystem and another aspect of that feeding relationship, such as… Energy at each trophic level Biomass at each trophic level Population at each trophic level

Energy Pyramid Diagram showing a feeding relationship and the total energy at each trophic level. Energy measured in kJ, J, or cal. 10% rule – approximately 10% of energy contained in a trophic level is available to the next trophic level (90% is “used”)

Biomass Pyramid Shows the consumable Biomass for each trophic level.

Pyramid of numbers Shows the population of each trophic level

Lab 2-3: Owl Pellets Calculate a pyramid of numbers and biomass pyramid for the barred owl based on observations from its pellets

Owl-Pellet Pyramid of Numbers Consumption for 1 owl for 1 year Predator Top-level consumer 1 Owl Prey Herbivores (mostly) Primary Consumers 2000-4000 Prey (mice, shrew, moles, birds) #? Producers (Plants)

Owl-Pellet Biomass Pyramid Consumption for 1 owl for 1 year Top-level Consumer .8 Kg Owl Primary Consumers 80 kg Mice, Shrews, Moles, Birds Producers 3,648 kg Plants, seeds, nuts, grains…