1. It all start with Plants!
Producers & Consumers,
It all start with Plants!

2. Prairie food web: Producers: grasses, clover & purple cone flowers.
1st level consumers ( herbivores): insects, mice, squirrels & bison
2nd or 3rd level consumer: spiders, snakes & hawks.
Decomposers: mushrooms, what else??

3. How do carnivores limit the number of animals below them in the food web??
Without snakes, the number of mice in the prairie ecosystem would keep increasing. In time, the mice would eat all the available food. Then the mice would starve, & so would the hawks, which eat mice.
Organisms in an ecosystem depend on one another for survival. A change in the number of 1 kind of organism can affect the entire ecosystem.

4. Pond food web: Producers: water plants & algae.
1st level consumers ( herbivores): insects, & tadpoles.
2nd or 3rd level consumer: fish, some birds ,such as, ducks( herbivores) while others are carnivores( turtle).
Decomposers:
Snails, worms & protist.

5. Energy Pyramid:
It’s a diagram that shows how much food energy is passed from each level in a food chain to the next level.

6. Energy Pyramid:
Producers use about 90% of the food energy they produce for their own life processes, they store the other 10% in their roots, stems, leaves, seeds & fruits.
So, not all the food energy of plants is passed on to the herbivores that eat them( only 10%).
Herbivores then use for their life processes 90% of the energy they got from the producer. They store the other 10% in their bodies.
So, an energy pyramid shows that each level of a food chain passes on less food energy than the level before it.

7. Predator – Prey relationship:
Prey: is an animal that is eaten by a predator .
Examples: mice & rabbits.
Predator: is an animal that kills & eats other animals.
Examples: Wolves & hawks.

8. Predator – Prey relationship:
The number of Prey & Predators are closely related??: any change in one leads to a change in the other.
Examples:
1- What happens if a prey’s animal food supply increase??
2- What happens if a drought kill much of the grass & other plants in an ecosystem??
It’s easy to see why predators need prey. However, prey need predators, too??
Otherwise, prey populations would grow very large. Then the prey would have to compete with each other to meet their basic needs. Many would end up starving.