Chapter 3 Topic 4: Trophic levels
and Ecological Pyramids
By: Yuhui Lee
Anne Chien
Sabrina Chang
Trophic Level
• Each step in a food chain or food web.
Ecological Pyramids
• Pyramids that show
the relative amount of
energy or matter
contained within each
trophic level in a
given food chain or
food web.
Biomass
• The total amount of living tissue within a
given trophic level.
Pyramid of Energy
• Phytoplankton :
Ex: Algae, bacteria,
seaweed
• Zooplankton:
Ex: jellyfish, krill,
mollusks
Pyramid of Energy
• As pyramid gets
narrower  less
amount of energy
• Why?
energy used to grow
and develop. Others
change into kinetic
energy and heat
energy
Pyramid of biomass
• Shows the relative
amount of living
tissue at each trophic
level.
• Higher trophic level
lower biomass
Pyramid of Numbers
• Number of individual
animals at each
trophic levels
• Higher level  fewer
organisms
Sources
• http://www.ehow.com/info_8361655_biomass-pyramidsorganisms-ocean.html
• http://kingfish.coastal.edu/biology/sgilman/770Food%20
WebsChallenges.htm
• http://www.buzzle.com/articles/biomass-pyramid-ofbiomass.html
• http://www.encyclopedia.com/topic/pyramid_of_numbers.
aspx#1-1O6:pyramidofnumbers-full#11O6:pyramidofnumbers-full
• Science textbook
Picture Sources
• http://www.bcb.uwc.ac.za/sci_ed/grade10/ecology/trophi
cs/troph.htm
• http://library.thinkquest.org/J0113170/forest/images/food
web.jpg
• http://kingfish.coastal.edu/biology/sgilman/770Food%20
WebsChallenges.htm
• http://www.eoearth.org/files/114301_114400/114359/320
px-Ecological_pyramid.gif
• Microsoft office powerpoint clipart