Post on 21-Dec-2015
What is the main source of energy in all ecosystems?
The Sun!
Interactions & interdependence in an ecosystem are all about energy transfer!
Meaning, when studying how/why organisms interact & the roles they play in their environment, we have to understand how energy
is flowing through the environment!
Feeding Relationships
Autotrophs/Producers
• Organisms that can make their own food from the sun or chemicals
Some bacteria can make their own food from chemicals, called
chemosynthesis.
Plants make their own food using energy from the sun via
photosynthesis.
Heterotrophs/ Consumers
Organisms that eat or absorb food to obtain energy
Different Types of Heterotrophs
• Herbivores: eat only plants (aphids)
• Carnivores: feed on other consumers (tigers)
• Omnivores: eat producers & consumers (bears)
Different Types of Heterotrophs
• Detritivores & Scavengers: feed on dead materials (vulture)
• Decomposers: break down organic matter and return it to the environment to be recycled (fungi)
Scavengers vs. Decomposers
• Scavengers feed off dead animal materials, consuming the organic matter.
• Decomposers break down organic matter & create inorganic matter that will be returned to the soil.– In other words, they break down decaying plants or animals
into simpler chemicals that can be recycled through the environment.
Heterotroph & Omnivore!
A. Heterotroph & CarnivoreB. Autotroph & HerbivoreC. Heterotroph & DecomposerD. Autotroph & DecomposerE. Heterotroph & OmnivoreF. Autotroph & Producer
Heterotroph & Decomposer!
A. Heterotroph & CarnivoreB. Autotroph & HerbivoreC. Heterotroph & DecomposerD. Autotroph & DecomposerE. Heterotroph & OmnivoreF. Autotroph & Producer
Autotroph & Producer!
A. Heterotroph & CarnivoreB. Autotroph & HerbivoreC. Heterotroph & DecomposerD. Autotroph & DecomposerE. Heterotroph & OmnivoreF. Autotroph & Producer
Heterotroph & Carnivore!
A. Heterotroph & CarnivoreB. Autotroph & HerbivoreC. Heterotroph & DecomposerD. Autotroph & DecomposerE. Heterotroph & OmnivoreF. Autotroph & Producer
Food Webs & Food Chains
• Show how energy flows through an ecosystem• Energy Flow: energy flows in 1 direction through an
ecosystem
Sun Producers Consumers Decomposers
At each level, some energy is used by the organism for life processes & is “lost” as heat.
Food Chains
• Single display of energy transfer in an ecosystem – arrows point in the direction of energy flow
The snake gets energy from eating frogs, so the arrow points toward the
snake.
Food Webs
• Link together several food chains within the same ecosystem
Trophic Levels
Steps or levels in a food web, chain, or food pyramid
Producers
Primary consumers
Secondary consumers
Tertiary consumers
Trophic Levels
Each consumer depends on the trophic level below
it for energy.
The 1st trophic level always includes producers; the 2nd
includes primary consumers, etc.
Primary consumer
Secondary consumer
Tertiary consumer
Trophic Levels
What trophic level do weasels belong to?
A. ProducerB. Primary
ConsumerC. Secondary
ConsumerD. Tertiary
Consumer
Secondary Consumer
What trophic level do raccoons belong to?
A. ProducerB. Primary
ConsumerC. Secondary
ConsumerD. Tertiary
Consumer
Primary AND Secondary Consumer!
• To show relative amounts of matter & energy per trophic level, we can use a pyramid.– Energy Pyramid– Biomass Pyramid
Ecological Pyramids
Energy PyramidsProducers at the bottom with the total amount of solar
energy captured
Notice how the amount of energy changes with every
trophic level.
Energy from the sun is captured in plants.
Food chains usually go up only 4-5 levels.
WHY?
Energy transfer is inefficient!
10% Rule
• Only 10% of the energy is passed on to the next trophic level.
Why?
The other 90% is used by the organism for life processes or lost as heat.
Inefficiency of Energy Transfer
• What do we mean by “lost” as heat?To where is this energy lost?
10-15% Growth
35-40% Cellular
Respiration
50% Waste (feces)
Only this energy moves on to the next level in
the food chain!
Energy lost to daily living.
If 5600 kCal were available at the producer level, how much would be available at each of the other trophic levels?
5600 kCal
560 kCal
56 kCal
5.6 kCal
Biomass Pyramids
Show the amount of food or energy available at each trophic
level as a weighted mass