Energy in an Ecosystem

Objectives: •Students will describe the flow of energy through an ecosystem.

Review from our Reading:

• What is a Producer or Autotroph?• What is a Consumer or Heterotroph?• Where does all of the energy in an

ecosystem originally come from?

Energy Transfer

• All organisms need energy to grow, move and reproduce

• In an ecosystem, the ultimate source of energy comes from the sun

• Plants use that energy to make it’s own food, and then other organisms eat those plants to get energy.

Producers

• Organisms that make their own food are called autotrophs.

• Photosynthetic – using the sun to power food production

• Examples: Plants, some kinds of bacteria, protists (plant-like algae), seaweeds, phytoplankton?

Consumers

• Heterotrophs – organisms that cannot make their own food

• How do they get their energy? By eating other organisms.

• They are grouped by what they eat.

Primary consumers = Herbivores

• Eat producers (plants)• Zebra that eat grass

is an herbivore• Other examples:

grasshoppers, caterpillars

Consumers: Carnivores

• Eat other consumers • Lions eat zebra• Praying mantis eats

grasshoppers

Consumers: Omnivores

• Eat both producers and other consumers

• Bears eat berries from a plant (producer) and also fish

Consumers: Scavengers

• Feed on the “Garbage” of the ecosystem

• Ex. Fallen leaves and branches, dead organisms

• Vultures

Decomposers

• Break down dead tissues (decay)

• Decay “recycles” nutrients

How is a food web different from a food chain?

What does the direction of the arrow tell you?

Remember that energy is replenished by the sun and that energy flows in the ecosystem from one level to the next.

How Energy flows through an ecosystem

• 1st Step Producers• 2nd Step Primary

Consumers that eat producers

• 3rd Step Secondary Consumers that eat other consumers

• 4th Step Tertiary Consumers that eat secondary consumers

Figure 19.26

Tertiary consumers

Secondary consumers

Primary consumers

Producers

10 kcal

100 kcal

1,000 kcal

10,000 kcal

What happens to energy as you go up trophic levels? Where does the rest of the energy go?

Biomass

• When plants photosynthesize, they use the energy from the sun to make sugar. The sugar is used for plant growth, reproduction

• When plants grow and reproduce they add organic (living) material to the ecosystem

• Biomass=the total weight of living matter in an ecosystem.