Download Energy Flow in Ecosystems

Energy Flow in
Ecosystems
Food Chains & Food Webs
Energy
• Energy flows in a one-way stream from primary producers to
various consumers through the food chain
Food Chains
• Food chains are series of steps in which organisms
transfer energy by eating and being eaten
• Producer  Herbivore  Carnivore
Food Webs
• Feeding relationships are usually
more complex than just a simple
chain
• Many animals eat more than
one kind of food
• Complex networks of feeding
relationships are called food
webs.
Everglades food web
- Describe three food
chains that are part of
this web?
- What role do
decomposers play in a
food web?
- Why is a food web a
more accurate
representation of feeding
relationships than a food
chain?
Trophic Levels
• Each step in a food chain or
food web is called a trophic
level
• “nourishment level” Carnivores/
omnivores
herbivores
autotrophs
Carnivores/omnivores
Food Webs & Disturbances
• Keystone species: a
species that has an unusually
large effect on its ecosystem
• Ex: sea otters
Ecological Pyramid Models
• Pyramids model the distribution
of energy and matter in an
ecosystem.
• Three types you need to know:
• Energy Pyramid
• Biomass Pyramid
• Pyramid of Numbers
Energy Pyramid
• Shows the amount of energy
available at each trophic level of
a food chain or food web.
• Only a small portion of energy in
each trophic level makes it to
the next level
• 10% rule
Between each trophic level 90% of energy is lost to the
atmosphere as heat. Only 10% of energy is transferred
from one level to the next.
Ecological Pyramids
Pyramid of Numbers
Shows the individual number of organisms
at each trophic level.
Biomass Pyramid
Measures the total dry mass of organisms at
each trophic level.