Energy in an Ecosystem Objectives: Students will describe the flow of energy through an ecosystem.

Review from Characteristics of Life: What is an Autotroph? What is a Heterotroph?

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 1 st Step Producers 2 nd Step Primary Consumers that eat producers 3 rd Step Secondary Consumers that eat other consumers 4 th Step Tertiary Consumers that eat secondary consumers

Figure 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.