Standard S7L4 Students will examine the dependence of organisms on one another and their environment.

I can explain interdependence within an ecosystem? Learning Target I can explain interdependence within an ecosystem?

Food Chains and Webs

A food chain shows how each living thing gets its food. A food chain always starts with producers and ends with consumers.

How to ….. The diagram depicts a food web. The arrows are drawn from food source to consumer. The arrows mean “eaten by.” or “Energy Transferred”

Producers and Consumers                                                                                                                   Producers and Consumers Plants, Algae and Cyanobacteria are producers. Consumers: Herbivore----eats plants Carnivore----eats meat Omnivore----eats meat & plants Decomposer/Saprophyte----recycles by enzymes Scavangers—eat dead organisms Detritivores---Insects, eat detritus

consumers The herbivores are called primary consumers. Carnivores that eat herbivores are called secondary consumers. Next Level: Carnivores that eat other carnivores are called tertiary consumers. Example: Phytoplankton Small Fishes Seal Killer Whale The top of the food chain has the top predator or apex.

Some Food chains… may have a fourth level consumer called a quaternary consumer. Consumers above this level will get very small amounts of energy.

Why are there more herbivores? In a food chain, energy is passed from one link to another. When a herbivore eats, only a fraction of the energy that it gets from producers is stored in the body. The rest is used by the organism to carry out life processes.

Energy for Carnivores When the herbivore is eaten by a carnivore, only a small amount of energy is transferred to the carnivore. The carnivore then has to eat many herbivores to get enough energy. Because of the large amount of energy that is lost at each link, the amount of energy that is transferred gets to be less and less. In other words,…….

The energy pyramid shows many trees & shrubs providing food and energy to giraffes. Note that as the energy moves farther up the food chain, there are fewer & fewer consumers. A large base is required to support a few at the top.

                                                                                                                                 Interdependence The interdependence of the populations within a food chain helps to maintain the balance of plant and animal populations within a community.

Food Chain http://www.sheppardsoftware.com/content/animals/kidscorner/games/foodchaingame.htm

For Example: When there are too many giraffes, there will be insufficient trees and shrubs for all of them to eat. Many giraffes will starve and die. Fewer giraffes means more time for the trees and shrubs to grow to maturity and multiply. Fewer giraffes also means less food is available for the lions to eat and some lions will starve to death. When there are fewer lions, the giraffe population will increase. It all works toward a level of balance.

Most food chains have no more than four or five links. There cannot be too many links in a single food chain because the animals at the end of the chain would not get enough food/energy to stay alive. Most animals are part of more than one food chain and eat more than one kind of food. Diversity ensures survival. The interconnected food chains form a food web.

Food Web http://teacher.scholastic.com/activities/explorer/ecosystems/be_an_explorer/map/form_wildcats.htm# http://www.harcourtschool.com/activity/food/meadow_activity.html