Energy Flow 1 Food Chains and Food Webs

Energy Flow 1

Food Chains and Food Webs Block 1 Energy Flow within Ecosystems Block 2 Biogeochemical Cycles Block 3 2

Food Chains and Food Webs 3 BLOCK 1 Food Chains & Food Webs

Essential question • The transfer of energy in an ecosystem is referred to as “energy flow”, and not “energy cycling”. Explain. 4

“troph” – to nourish • Autotroph are producers that make their own food. • Heterotrophs are consumers that must eat food to obtain energy. 5

“Vore” - to eat • Herbivore - a plant eater • Carnivore - an organism that obtains nutrients from the blood or flesh of an animal • Omnivore - an organism which eats both plant and animal matter 6

Decomposer and Detritivore • Detritivore - a consumer that obtains its nutrients from detritus (dead organic matter) – Ex: Scavengers, worms, vultures • Decomposer – break down and absorb nutrients from dead organisms. – Also release nutrients – Ex: Bacteria, fungi (mushrooms) 7

Food Chain • A food chain is the series of organisms showing feeding relationships. A food chain usually begins with a green plant (producer) which is eaten by an animal (consumer). The arrow means 'is eaten by', and shows the flow of energy along the food chain. Producer -> Consumer 1 -> Consumer 2 -> Consumer 3 -> Herbivore Carnivore 8 Carnivore

Food Web A network of interrelated food chains in a given area 9

Producers & Consumers • Producer – Usually plants that produce their own food by photosynthesis. • Primary Consumer – Herbivores that eat plants. • Secondary Consumer Carnivores that eat herbivores. • Tertiary Consumer Carnivores which eat other carnivores. • Apex Predator which have no predators are at the top of the food chain. 10

Consumers • Secondary consumers (eat herbivores) • Tertiary consumers (carnivores that eat other carnivores) Primary consumers (Herbivores) • Examples • Giraffe • Catapillar • Zooplankton • Omnivores(herbivore+carnivore) Fig. 3 -8 a, p. 60

Trophic Level • A trophic level is each level in a food chain. 12

Trophic Levels 1 st trophic level = producers 2 nd trophic level = primary consumer 3 rd trophic level = secondary consumer 4 th trophic level = tertiary consumer 13

Check for understanding: Let’s Guess The Order of the Trophic levels together… Trophic Level 2 Trophic Level 4 Trophic Level 3 Trophic Level 1 14

Number Pyramid Three Types of Pyramids Energy Pyramid 15 Biomass Pyramid

10% Rule • When one animal feeds off another, only about 10% of the available energy is transferred. – There is a loss of energy in the form of heat in the process. – Additional loss of energy occurs during respiration and movement of the organisms before they are eaten. • More and more energy is lost as one moves up through trophic levels. 16

Usable energy available at each trophic level (in kilocalories) Tertiary consumers (human) 10 Secondary consumers (perch) 100 Primary consumers (zooplankton) Heat Decomposers Heat 1, 000 Heat 10, 000 Producers (phytoplankton) Fig. 3 -14, p. 65

ENERGY FLOWS and is Transformed Law of Conservation of Energy: �Energy can NOT be created nor destroyed �Energy CAN be degraded �Always goes in the direction of HIGH quality energy ----> LOW quality energy 18

Do Now: Construct a Food Web 19