1. Food Web notes

2. Autotrophs
Organisms that can use the energy in sunlight to convert water & CO2 into food via photosynthesis.
Also called Producers b/c they produce all of the food that heterotrophs use.
Ex. Plants, Algae, & some bacteria

3. Autotrophs

4. Autotrophs Chemotrophs
Autotrophs that convert chemicals into energy via chemosynthesis.
Ex. Bacteria

5. Heterotrophs Organisms that do not make their own food
Also called Consumers b/c they consume other organisms in order to live.
Ex. All animals, Mushrooms

6. Heterotrophs

7. Heterotrophs Consumers 1. Detrivores (Scavengers) – feed on the
tissue of dead organisms
Ex. – Crabs, Shrimp, etc.

8. Heterotrophs Consumers 2. Herbivores – eat only plants
Ex. – Krill, Parrotfish
3. Carnivores – eat
only meat
Ex. – Sharks, Seals

9. Heterotrophs Consumers plants & animals Ex. – Sea Otters, Humans
4. Omnivores – eat both
plants & animals
Ex. – Sea Otters, Humans
5. Decomposers – absorb
dead material &
break it down into
nutrients
Ex. – Bacteria

10. Trophic levels
Energy moves from one organism to another when it’s eaten.
Each step in this transfer of energy is a trophic level.

11. Transfer of energy
Energy is neither created nor destroyed, it just changes forms.
Only 10% of the energy from each level is transferred to the biomass of the next level. The rest is used up in daily living.
Biomass - the total mass of the organic matter

12. The 10% rule

13. Food chains Energy flow from one trophic level to the next.
Involves only one organism at each trophic level.
Primary Consumers – eat autotrophs (producers)
Secondary Consumers – eat primary consumers
Tertiary Consumers – eat secondary consumers
Decomposers – break down dead organisms

14. Food chains Notice that the arrow points in the direction of
the energy
transfer, NOT
“what ate
what”

15. Food webs Most organisms eat more than JUST one organism.
Food webs are more complex & show many organisms.

16. Trophic pyramids Shows the relationship between organisms in an
ecosystem &
which level has
the most energy
& the highest
# of organisms.

17. Trophic pyramids Which level has the most energy? the bottom level
Which level has the most organisms?
Which level has the least organisms?
Which level has the least energy?
the bottom level
the bottom level
the top level
the top level