MRS. SANDY GÓMEZ 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 Ecosystems Food web – a network of complex feeding interactions Trophic levels – each step in a food chain or food web  1 st – producers  2 nd – primary consumers  3 rd – secondary consumers  4 th – 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

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 Ecosystems Energy Pyramid:  Shows the lost of energy from one level to the next.  Trophic levels are stacked in blocks.

Energy Flow in Ecosystems Biomass Pyramid Biomass 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 Ecosystems Number 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