1. Chapter 2.5
Food Webs and Ecological Pyramids

2. Ecological Niche
Ecological Niche – the role a species serves in its ecosystem
including what it eats, what eats it, and how it behaves
No 2 species have the same ecological niche

3. Example: Black Bear
Example: a black bear’s ecological niche – it eats plants/berries/nuts/small animals, hibernate in the winter, have few predators, insects feed on them
What’s your ecological niche?

4. Feeding Roles Herbivore – animal that eats plants/producers
Carnivore – animal that eats other animals
Omnivore – animals that eats plants and animals
Scavenger – animal that feeds on the remains of another organism

5. Food Chains
The most common interactions between species is their feeding relationship
Food Chain – a sequence of organisms, feeding on the next, transferring energy

6. Trophic Levels
Trophic Level – a way to describe the level of an organism, depending on where it is in the food chain
Producers are always the 1st trophic level (the lowest)
Herbivores are always the 2nd trophic level (they eat the producer)
Carnivores occupy 3rd, 4th, 5th, etc

8. Food Webs Food chains don’t exist in nature…food webs do
Food Web - the feeding relationships within a community
Very complex
An interconnecting set of food chains
Stable
Arrows always point to what eats it

9. Practice Write down as man food chains as you see in this food web
Now, label their tropic levels

10. Food webs help us figure out what happens if a species is removed or added to an ecosystem

11. Ecological Pyramids
Ecological Pyramids – a way to display the relationship between trophic levels
There are 3 types of pyramids: energy pyramids, numbers pyramids, and biomass pyramids

12. 1. Energy Pyramid
Illustrates the energy loss and transfer between levels
A very small amount of energy gets passed on to the next trophic level (only 10%)
This energy is used/wasted on growing, breathing, reproduction, heat loss, etc

13. 2. Numbers Pyramid
A representation of how many (#) of a certain species are present
Usually, the 2nd level is the biggest

14. 3. Biomass Pyramid
Because less energy gets passed on to the top of the food chain, there are so many less predators at the top of the food chain
Example: what is there more of…grass or hawks?
Biomass - the total mass (kg) of all organisms in the trophic level in a given area
Species at lower parts of the food chain have more energy

15. Homework
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