1. Energy Flow in Ecosystems
Lesson Overview
Energy Flow in Ecosystems
Food Web / Food Chains
Producers, Consumers, and Decomposers

2. 1. How Organisms Get Matter and Energy
-The ultimate source of the energy for life on earth is the sun. -Energy is the ability to cause change.
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3. -Matter and energy flow (move) through the environment in cycles.
-Animals and plants depend on these cycles to get the food and nutrients they need to survive.
-There are 2 main categories of organisms in the environment; autotrophs and heterotrophs.
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4. Autotrophs are primary producers; they make their own food through a process called photosynthesis.
Ex: Trees, plants, algae.
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5. Heterotrophs are consumers; they must eat to get food.
Ex: Lions, Humans, Rabbits.
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6. Consumers Types of Consumers
Organisms that must acquire energy from other organisms by ingesting in some way are known as heterotrophs.
Heterotrophs are also called consumers.
Types of Consumers
Carnivores – organisms that obtain their energy by eating meat or animals
Example: snakes, dogs, cats, and this giant river otter.
Herbivores – organisms that obtain their energy by eating plants Example: cows, caterpillars, and deer
Omnivores - an organism that obtains organic food molecules by eating other organisms or their products (they eat plants and animals).
Example: Humans, bears, and pigs

7. Types of Consumers
Decomposers - feed by chemically breaking down organic matter. The decay caused by decomposers is part of the process that produces detritus—small pieces of dead and decaying plant and animal remains.
Example: bacteria and fungi
Detritivores - feed on detritus particles, often chewing or grinding them into smaller pieces. Detritivores commonly digest decomposers that live on, and in, detritus particles.
Example: giant earthworms

8. Energy Pyramids
An energy pyramid is a graphical model of energy flow in a community.
The different levels represent different groups of organisms that might compose a food chain.
Food chain: shows who’s eating who in the community.

9. Trophic Levels
When one organism eats another, molecules are metabolized and energy is transferred.
As a result, energy flows through an ecosystem from producers to consumers.
A trophic level is an organism’s position in a sequence of energy transfers in a food chain or food pyramid.
Examples include producers and primary, secondary and tertiary consumers.

10. The Triangle Shape Why are energy pyramids shaped the way they are?
It shows the amount of useful energy that enters each level.

11. 90% of the energy is consumed (at each level) only 10% is passed to the next level.

12. 10% Rule
When one animal feeds off another, only about 10% of the available energy is transferred.
There is a loss of energy in the form of heat in the process.
Additional loss of energy occurs during respiration and movement of the organisms before they are eaten.
More and more energy is lost as one moves up through trophic levels.

13. Trophic Levels
Organisms that get their energy from nonliving sources (sun, organic matter) are called autotrophs (or producers) and make up the 1st trophic level.
Primary consumers make up the 2nd trophic level. These are usually herbivores that eat plants.
The 3rd trophic level consists of secondary consumers that eat primary consumers, and are primary carnivores.
The 4th trophic level consists of tertiary consumers (or secondary carnivores).

14. Food Chain
A food chain is the series of organisms showing feeding relationships. A food chain usually begins with a green plant (producer) which is eaten by an animal (consumer). The arrow means 'is eaten by', and shows the flow of energy along the food chain.
Producer -> Consumer 1 -> Consumer 2 -> Consumer 3 ->
Herbivore Carnivore Carnivore
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15. A network of interrelated food chains in a given area
Food Web
A network of interrelated food chains in a given area
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16. Food Web Homework Project
Cut and color the organisms
Glue them onto the blank side
Using the chart on what each organism eats, draw arrows showing where each organism is getting its energy from.