Energy Flow Through an Ecosystem Food Chains, Food Webs, Energy Pyramids

What is the ultimate source of energy on Earth? The Sun

How does the energy from the sun reaches Earth? What happens to sunlight wave when it gets to Earth? It is captured by some organisms (mostly plants, but some bacteria and algae too) Photosynthesis

The chemical reaction by which green plants use water and carbon dioxide and light from the sun to make glucose. ENERGY is stored in glucose; glucose is stored as starch.

Organisms that can make glucose during photosynthesis are called AUTOTROPHS or PRODUCERS.

Troph = to feed Auto= self Autotroph = feeds itself

Autotrophs/Producers use most of the energy they make for themselves.

The energy that is not used by producers can be passed on to organisms that cannot make their own energy.

Organisms that cannot make their own energy are called HETEROTROPHS or CONSUMERS.

Consumers that eat producers to get energy: Are first order or primary consumers Are herbivores (plant-eaters)

Most of the energy the primary consumer gets from the producer is used by the consumer.

Some of the energy moves into the atmosphere as heat.

Some energy in the primary consumer is not lost to the atmosphere or used by the consumer itself. This energy is available for another consumer.

A consumer that eats another consumer for energy: Is called a secondary or second order consumer May be a carnivore May be a predator May be a scavenger

Most of the energy the secondary consumer gets from the primary consumer is used by the secondary consumer.

Some of the energy is lost as heat, but some energy is stored and can passed on to another consumer.

A consumer that eats a consumer that already ate a consumer: Is called a third order or tertiary consumer May be a carnivore May be a predator May be a scavenger

Consumers that eat producers & other consumers Are called omnivores Omnivores eat plants and animals

Consumers that eat other consumers that have already died are called scavengers.

Decomposers: break down waste and dead organisms and return the raw materials to the environment. Ex. Bacteria, fungi

The transfer of energy from sun to producer to primary consumer to secondary consumer to tertiary consumer can be shown in a FOOD CHAIN.

Trophic Level Each step in a food chain is called a trophic level. Think of it as a feeding level. 1st trophic level: autotrophs/producers 2nd trophic level: primary consumers 3rd trophic level: secondary consumers 4th trophic level: tertiary consumers 5th trophic level: quaternary consumers

On your own Draw an example of a food chain Label the trophic levels Label producers and consumers

Another way of showing the transfer of energy in an ecosystem is the ENERGY PYRAMID.

Energy pyramids show That the amount of available energy decreases up the food chain It takes a large number of producers to support a small number of primary consumers It takes a large number of primary consumers to support a small number of secondary consumers

3 types of pyramids Energy Pyramid Biomass Pyramid Biomass: total mass of living matter at each trophic level.

Pyramid of Numbers: each level represents the number of individual organisms consumed by the level above it

10% law Only about 10% of energy is transferred from one level to the next The other 90% is used by the organism to carry out its life processes or it is lost to the environment

Food Webs: Are interconnected food chains They show the feeding relationships in an ecosystem

Acknowledgement Adapted from www.science-class.net/PowerPoints/Energy_Flow.ppt