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MRS. SANDY GÓMEZ
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Are the feeding relationships between organisms.
A Food Chain is: transfer of food energy from its source (plants and
other autotrophs) through herbivores (primary consumers) to carnivores (secondary and tertiary consumers)
Energy Flow in Ecosystems
Energy flows through an ecosystem in one direction (sun → producers → consumers)
Food chain – a series of steps in which organisms transfer energy by eating and being eaten
Energy Flow in Ecosystems
Food chains are never isolated, they hook together to make food webs.
Energy Flow in Ecosystems
Food web – a network of complex feeding interactions
Trophic levels – each step in a food chain or food web 1st – producers 2nd – primary
consumers 3rd – secondary
consumers 4th – tertiary
consumers
Energy Flow in Ecosystems
What transforms a food chain into a food web? A species appears into
the web in more than one trophic level
Most consumers are not exclusive May appear as
carnivores, omnivores, etc
Energy Flow in Ecosystems
Trophic Levels in
Food Chains
Energy Flow in Ecosystems
Trophic levels are the levels in a food chain.
Food chains are limited to 4-5 trophic levels.
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Types of ecological pyramids:
Energy Pyramid – shows the amount of energy available
at each trophic level
Only about 10% of the energy is transferred to the next
level
Biomass Pyramid – shows the amount of living tissue
within each trophic level
Pyramid of numbers – shows the number of organisms
at each trophic level
Energy Flow in Ecosystems
Energy Pyramid: Shows the lost of energy from one level to the next. Trophic levels are stacked in blocks.
Energy Flow in EcosystemsBiomass Pyramid Shows the
total dry weight of all organisms in a trophic level
Most of this narrow sharply from base to top
In some aquatic ecosystems pyramids are inverted
Energy Flow in Ecosystems
Number Pyramid Shows the exact amount of organisms at each trophic
level in the ecosystem
Energy Flow in Ecosystems
CLASSWORK
Make a diagram showing the main trophic levels
Give 2 examples of terrestrial food chains
