Ecological Pyramids
Ecological pyramids are graphical representations of the trophic structure of
ecosystems. Ecological pyramids are organized with plants on the bottom,
herbivores above the plants, and carnivores above the herbivores. Top carnivores
will be at the apex of the ecological pyramid.
There are three types of ecological pyramids, energy, numbers and biomass.
When energy is passed along a food chain there are substantial energy losses that
occur during each transfer.
When an organism consumes another organism it will obtain both physical matter
and chemical energy from that organism. Only about 10% of the energy that is
taken in at one trophic level is passed on to the next level.
Species at the bottom of the pyramid will have more energy available to them
than species will have if they are near the top. This therefore results in
populations at the bottom of the pyramid remaining much higher than those at
the top.
Pyramid of Energy:
Shows the amount of energy absorbed at each level
Pyramid of Numbers:
Shows the number of individuals of all populations in each trophic level
Pyramid of Biomass:
Shows the total mass of organisms at each trophic level. Biomass: Is the mass of living
Human Impact on Food Chains and Webs
biological organisms in a
given area or ecosystem at a
given time.
Humans have the ability to have a great impact on ecosystems. Living organisms
are a significant portion of any ecosystem, therefore any activity that affects an
ecosystem is also likely to affect the organisms within that ecosystem. If
organisms are affected the food chains webs that the organisms are a part of will
also feel the effects.
Pyramid of Energy
Pyramid of Numbers
Pyramid of Biomass
Homework Quiz
1. What is the title of the article?
2. Describe the seasonal habitats and the ecological niche of the polar bear.
3. According to the article, what is the number one treat to the survival of the mammal?
4. What is the estimated world population of polar bears? What percentages live in Canada?
5. Why are the bears getting thinner? What abiotic factors are causing this phenomenon?
6. What is the value in doing my homework?