How organisms get energy
Ecosystem Energy
• The ultimate source of energy on Earth is the
Sun
• Autotrophs-get energy from the sun to make
food
• Heterotrophs-must eat other organisms to get
energy
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Trophic Levels (feeding steps)
• Producers-Autotrophs
– Mostly Plants
• Primary Consumers-1st order heterotrophs
– Eat Producers (herbivores)
• Secondary Consumers-2nd order
heterotrophs
Carnivores
Omnivores
Herbivores
Decomposers
(Detrivore)
Food Chain
• Shows how matter and energy move
through an ecosystem
• Each organism in a food chain represents
a trophic level
– Eat Primary Consumers
• Tertiary Consumers-3rd order heterotrophs
– Eat Secondary Consumers (top predators)
Food Web
• Models that show all possible feeding
relationships at each trophic level in a
community
RULE OF 10
• Only 10% of energy is transferred from
one trophic level to the next.
• Example:
– It takes 100 kgs of plant materials (producers)
to support 10 kgs of herbivores
– It takes 10 kgs of herbivores to support 1 kg of
1st level predator
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