Energy and Ecology

Ecosystem Components• Producers

– Basis of an ecosystem’s energy

– Autotrophs: perform photosynthesis to make sugars

– Chemotrophs: Bacteria which use minerals from deep-sea vents to make energy

• Consumers– Heterotrophs: Consumes

others for energy– Omnivores, herbivores,

carnivores, decomposers, detritivores

• Defined: Feeding level of an ecosystem

• Trophic levels consist of producers, consumers, and decomposers

• ~10% of energy is passed to the next level– ~90% used by the organism or lost

as heat– Food chains contain few trophic

levels

• 1st trophic level = Producers• Autotrophs (perform photosynthesis)• Bottom of food chain• Ex: Plants, algae, cyanobacteria

• 2nd trophic level = Primary consumers• Feed on producers• Herbivores (plant eaters)

• 3rd trophic level = Secondary consumers• Feed on primary consumers• Omnivores and carnivores

• 4th trophic level = Tertiary consumers• Feed on secondary consumers• Omnivores and carnivores

• 5th trophic level = Quaternary consumers• Feed on Tertiary consumers• Omnivores and carnivores

• Rarely shown on food chains

• Feed on any food chain level when it dies

• Detritivores: Feed/ingest dead matter

• Decomposers: secrete enzymes to break down dead matter and then absorb the nutrients

What’s wrong with this food chain?The arrows are pointing the wrong direction.

This implies that the plant eats the grasshopper.

What’s wrong with this food chain?The arrows are pointing the wrong direction.

This implies that the grasshopper eats the mouse.

What’s wrong with this food chain?The arrows are pointing the wrong direction.

This implies that the mouse eats the snake.

What’s wrong with this food chain?The arrows are pointing the wrong direction.

This implies that the snake eats the hawk.

Much better…

The arrows show the direction that energy is passed up the food chain.

Label the tropic levels in this energy pyramid

• Defined: Group of interrelated food chains

• Arrows show direction energy (nutrients) travel

Analysis• Trace 2 food chains from

this food web.

producer

Primary consumer

Secondary consumer

Tertiary consumer

Highlight a food chain from this food web. Then label each trophic level.

producer

Primary consumer

Secondary consumer

Tertiary consumer

Quaternary consumer

Highlight a food chain from this food web. Then label each trophic level.

• Defined: Group of interrelated food chains

• Arrows show direction energy (nutrients) travel

Analysis• Trace 2 food chains from this

food web.• What could happen if the

grasshoppers die out due to pesticide use?

Spider death (no more

grasshoppers to eat)

Blue jay death (less spiders to eat)

Squirrel increase (less owls hunting them)

Owl death (less blue jays to eat)

YouTube Food Chain Video

Kobe Kuiz1. How many trophic levels are in the following food chain?

Apple tree Worms Blue Jay Owl

2. If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level?

3. In the food chain above, which is the producer?4. In the food chain above, which is the primary consumer?5. In the food chain above, which is the tertiary consumer?6. Which level consumer are herbivores known as?7. What is the lowest consumer level possible for a carnivore?8. Examine the food web on slide #10. Find a complete food chain that

is 6 trophic levels from start to finish.