Energy Flow in an Ecosystem

• Autotrophs: organisms that manufacture their own nutrients using stored energy or energy from the sun– Examples?

• Heterotrophs: cannot make their own food, they feed on autotrophs or other heterotrophs– Examples?

Energy Flow in an Ecosystem

Energy Flow in an Ecosystem• The sun is the ultimate source of energy for all

organisms

• Producers change light energy into energy they can use to grow.– Plants and other photosynthetic organisms

• Consumers eat other organisms instead of producing their own food

• Decomposers are organisms that break down the remains of organisms– Fungi, bacteria, some insects

Types of Consumers

• Herbivores: feed on plants– Rabbits, grasshoppers, squirrels, etc

• Carnivores: feed on other animals– Lions, snakes, wolves, etc

• Scavengers: feed on dead animals– Vultures, crows, etc

• Decomposers: break down and absorb nutrients from dead organisms– Fungi, bacteria, some insects

Energy Flow in an Ecosystem

• Energy flows through an ecosystem as one organism eats another. The way in which energy flows can determine how many species can live in an ecosystem.

• Each step in the transfer of energy through an ecosystem is called a

trophic level– In an ecosystem, energy flows from the sun

to producers to consumers to decomposers

Trophic Levels in an Ecosystem

Energy Flow in an Ecosystem• Food Chains

– In an ecosystem, energy flows from one trophic level to the next, forming a food chain

– Simple way to show flow of energy from one trophic level to the next

– Arrows point in the direction of energy flow

Energy Flow in an Ecosystem

• Food Webs– Energy does not follow

a simple pattern!– Many organisms eat

more than one kind of food

– A group of interconnected food chains form a food web

Energy Flow in an Ecosystem

• Energy is stored at each level of a food web and moves throughout trophic levels as organisms feed on each other. But not all of it is used; some of it dissipates as heat back into the environment and does not move on to the next trophic level….

Energy Flow in an Ecosystem

• Rule of 10 – Also called “The 10% Rule”

– Only TEN (10) PERCENT of the energy available in a trophic level will move on to the next!

– The other NINETY (90) percent is changed into heat energy!

Energy Flow in an Ecosystem

• Energy Pyramid– Triangular diagram that

shows an ecosystem’s loss of energy as it moves through a food chain

– Each layer represents one trophic level

• Producers are always at the base. They have the MOST energy!

• Consumers make up higher levels