Download Exploring the Nature of Energy Flow

Tuesday, Sept. 15th
Learning Goals
• Characterize feeding relationships and energy
flow, using them to construct trophic levels
and food webs
• Distinguish characteristics of a keystone
species
Agenda
Exploring the Nature of
Energy Flow
Chapter 6
• Ch. 5 Quiz
• Notes
Energy Flows through
Ecosystems
• Energy can’t be created or destroyed but can
change from one form into another
• Energy cannot be recycled, it flows only in ONE
direction
• Everything an organism does requires energy
– Life functions of organisms such as maintaining body
temperature, escaping predators, growing new cells or
pumping blood through the body
• Energy flow is the transfer of energy from one
organism to another
Energy Passes Through
Trophic Levels
• Trophic levels:
rank in the
feeding
hierarchy
– Producers
– Consumers
– Detritivores and
Decomposers
1
Producers: the first trophic level
• Autotrophs (“selffeeders”): organisms that
capture solar energy for
photosynthesis to produce
sugars
• EX: Green Plants,
Cyanobacteria, Algae
Consumers at Higher Trophic
Levels
• Tertiary Consumers: fourth trophic level
–
–
–
–
Predators at the highest trophic level
Consume secondary consumers
Can be carnivores or omnivores
Hawks, owls
Consumers
• Organisms that consume others for energy using
cellular respiration (heterotrophs)
• Primary consumers: second trophic level
– Organisms that consume producers
– Herbivores consume plants
– Deer, grasshoppers
• Secondary consumers: third trophic level
– Organisms that prey on primary consumers
– Carnivores consume meat
– Wolves, rodents
Detritivores & Decomposers
• Organisms that consume nonliving
organic matter
– Enrich soils and/or recycle nutrients found
in dead organisms
• Detritivores: scavenge waste products
or dead bodies called detritus
– Millipedes, worms, raven, coyote
• Omnivores: consumers that eat both plants
and animals
• Decomposers: break down leaf litter
and other non-living material
– Fungi, bacteria
– Enhance topsoil and recycle nutrients
2
Food Webs show Relationships &
Energy Flow
Connections within a Food Web
• Food chain: the
relationship of how energy
is transferred up the
trophic levels
• Food web: a visual map of
feeding relationships and
energy flow
– Includes many different
organisms at all the
various levels
– Greatly simplified; leaves
out the majority of species
Some Organisms Play Big Roles in
Food Webs
• Keystone Species have
a strong, wide-reaching
impact far out of
proportion to its
abundance
• Removal of a keystone
species has substantial
ripple effects
– Alters the food chain
– EX: wolves, otters,
elephants
Energy through Biomes
• Most energy organisms use
is lost as waste heat through
respiration
– Less and less energy is
available in each successive
trophic level
– Each level contains only 10%
of the energy of the trophic
level below it
• There are far fewer
organisms at the highest
trophic levels, with less
energy available
3
Energy Transfer
Energy Pyramids
• Show how much every is available at each
trophic level
4