MRS. SANDY GÓMEZ

Energy Flow in Ecosystems

Energy Flow in Ecosystems

Are the feeding relationships between organisms.

A Food Chain is: transfer of food energy from its source (plants and

other autotrophs) through herbivores (primary consumers) to carnivores (secondary and tertiary consumers)

Energy Flow in Ecosystems

Energy flows through an ecosystem in one direction (sun → producers → consumers)

Food chain – a series of steps in which organisms transfer energy by eating and being eaten

Energy Flow in Ecosystems

Food chains are never isolated, they hook together to make food webs.

Energy Flow in EcosystemsFood web – a network

of complex feeding interactions

Trophic levels – each step in a food chain or food web 1st – producers 2nd – primary

consumers 3rd – secondary

consumers 4th – tertiary consumers

Energy Flow in Ecosystems

What transforms a food chain into a food web? A species appears into

the web in more than one trophic level

Most consumers are not exclusive May appear as

carnivores, omnivores, etc

Energy Flow in Ecosystems

Trophic Levels in

Food Chains

Energy Flow in Ecosystems

Trophic levels are the levels in a food chain.

Food chains are limited to 4-5 trophic levels.

Energy Flow in Ecosystems

Energy Flow in Ecosystems

Types of ecological pyramids: Energy Pyramid – shows the amount of energy available

at each trophic level Only about 10% of the energy is transferred to the next level

Biomass Pyramid – shows the amount of living tissue within each trophic level

Pyramid of numbers – shows the number of organisms at each trophic level

Energy Flow in EcosystemsEnergy Pyramid:

Shows the lost of energy from one level to the next. Trophic levels are stacked in blocks.

Energy Flow in EcosystemsBiomass Pyramid Shows the

total dry weight of all organisms in a trophic level

Most of this narrow sharply from base to top

In some aquatic ecosystems pyramids are inverted

Energy Flow in EcosystemsNumber Pyramid

Shows the exact amount of organisms at each trophic level in the ecosystem

Energy Flow in Ecosystems

CLASSWORK

Make a diagram showing the main trophic levels

Give 2 examples of terrestrial food chains