1. Activity #16: Energy in a Ecosystem

2. EQ How do different organisms get the energy they need to survive?
How does energy move through an ecosystem?
What are some of the roles of the organisms in ecosystems?

3. Challenge Question
Describe how energy moves through an ecosystem.

4. Vocabulary Autotroph Food chain Chemosynthesis Food web Heterotroph
Consumer
Carnivores
Herbivores
Omnivores
Scavengers
Decomposers
Detritivores

5. Energy, Producers, and Consumers

6. Energy Organisms must get energy in order to function
Different organisms get their energy in different ways
Almost all energy on Earth starts from the sun!

7. 1. Autotrophs
Organisms that capture energy from sunlight or chemicals and turn it into food
Also called primary producers

8. Primary Producers
Most commonly use energy from the sun to create sugars and starches (photosynthesis)
Important examples: plants, algae, photosynthetic bacteria

9. Chemosynthesis
When primary producers turn the energy in chemicals (like hydrogen sulfide) into carbohydrates.
Mostly bacteria
Found in extreme environments (deep ocean, hot springs, volcanoes)

10. 2. Heterotrophs
Eat other organisms for food.
Also called consumers

11. Types of Consumers Classified by the way they acquire energy
* Put these definitions in the correct bubbles on pg. 5 in the notes.
Classified by the way they acquire energy
Carnivores- kill and eat other animals
Herbivores- eat plant materials
Omnivores- eat both plant and animal materials
Scavengers- consume carcasses of organisms that have died or that were killed by predators
Decomposers- feed by chemically breaking down organic matter into detritus, debris from decomposing plants and animals (Ex: fungi and bacteria)
Detritivores- feed on detritus particles (Ex: earthworms)

12. Energy Flows One Way Almost all energy on Earth starts from the sun!
Energy flows through an ecosystem in a one way direction from producers to consumers

13. Food Chain
Food Chain- a series of steps in which organisms transfer chemical energy by eating and being eaten.
food molecules are chemicals
Phytoplankton = algae that is floating and not attached to something
**Read an arrow as “is eaten by”

14. Food Webs
Algae
Plants
Food web- a network of complex interactions formed by the feeding relationships among the organisms of an ecosystem

15. Decomposers and Detritivores are Important in Food Webs
Dead plant and animal material must be broken down so the molecules can be reused for new life
Decomposers (bacteria and fungi) are heterotrophs that break down this dead plant and animal material into detritus
Releases nutrients into the soil for new primary producers to grow (“recycles nutrients”)
Detritus is eaten by detritivores (like crayfish, grass shrimp, and worms), further releasing nutrients into the soil

16. Food Web Disturbances
Environmental changes can cause changes in a food web
Krill

17. Think About It…
How would a decrease in the krill population affect the Antarctic food web?
What do ecologists mean when they say that killer whales indirectly depend on krill for survival?

18. Trophic Levels
Each step of a food chain or food web is called a trophic level
First trophic level- always primary producers
All other trophic levels are occupied by different types of consumers

19. Ecological Pyramids
Illustrations used to show the amounts of energy or matter in each trophic level of a food web
Three types of pyramids: energy, biomass, and numbers

20. Pyramids of Energy
Show the amount of energy available at each trophic level
Only 10% of the energy in one trophic level is passed to the next level up.
The rest of the energy is either used by the organisms to do life processes (like growth, reproduction, respiration, etc.), or released as heat
How much of the energy available to the producers is available to the third-level consumers?

21. Pyramids of Biomass
Biomass is the total amount of living tissue in a trophic level
Primary Producers will have the greatest biomass
There must be enough producers to provide energy for all of the consumers

22. Pyramids of Numbers
Show the number of individuals at each trophic level
If the main producer is a large organism, the base of the numbers pyramid will be small
Pyramid of Numbers
Grass
Pyramid of Numbers

23. Example **Read an arrow as “is eaten by”
Phytoplankton = algae that is floating and not attached to something
**Read an arrow as “is eaten by”

24. Example
Algae
Plants