3.3 Energy Flow in Ecosystems
POINT > Identify ways we conceptualize energy flow through ecosystems POINT > Describe food chains POINT > Describe food webs POINT > Describe ecological pyrami ds
A food chain is a series of steps in which organisms transfer energy by eating and being eaten
Each step in a food chain is called a trophic level The first level is always a producer
Each step is called a trophic level Consumers make up all the other levels Primary consumer (First Level) Secondary consumer (Second) Tertiary consumer (Third) Quaternary consumer (Fourth)
Arrows always point to where the energy is going
Phytoplankton: A mix of algae, the primary producers Zooplankton: A diverse mix of protists and tiny animals consuming the phytoplankton PhytoplanktonZooplanktonSmall Fish Large Fish Whale Ex. A marine food chain:
What trophic level are the “small fish”? Which organisms are the tertiary consumers? PhytoplanktonZooplanktonSmall Fish Large Fish Whale Ex. A marine food chain:
Food webs are more complicated networks of feeding interactions composed of many food chains
Ex. Antarctic Ecosystem
Everglades Marshland Ecosystem
Ecological pyramids show the relative amount of energy or matter contained at each trophic level in a food chain or web
Energy Pyramid: Shows relative amount of energy available at each trophic level Light Chemical Producer Primary Consumer Secondary Consumer Tertiary Consumer
Energy Pyramid: On average, only about 10% of energy available to a level is passed on Light Chemical Producer Primary Consumer Secondary Consumer Tertiary Consumer 100% 10% 1% 0.1%
Energy Pyramid: About 90% gets used up by the organism for various functions or is lost as heat Light Chemical Produce r Primary Consumer Secondary Consumer Tertiary Consumer Heat 100% 10% 1% 0.1% Maintaining Homeostasis
WB CHECK: How much energy is lost between two trophic levels? What are the primary producers in a marine food web?
Biomass Pyramid: Shows relative amount of living organic matter at each level Usually given as a mass per area
Numbers Pyramid: Shows relative number of individuals at each level
WB CHECK: In a biomass pyramid, where is the greatest amount of biomass, the top or bottom? True or False: A population of large predators has more total biomass than a population of smaller prey animals.
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