Activity #16: Activity #16: Energy in a Energy in a EcosystemEcosystem

EQEQ• 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?

Challenge QuestionChallenge Question• Describe how energy moves through an

ecosystem.

VocabularyVocabulary

Energy, Producers, and Energy, Producers, and ConsumersConsumers

EnergyEnergy• 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!

1. Autotrophs1. Autotrophs• Organisms that capture energy from

sunlight or chemicals and turn it into food

• Also called primary producers

Primary ProducersPrimary Producers• Most commonly use energy from the sun

to create sugars and starches (photosynthesis)

• Important examples: plants, algae, photosynthetic bacteria

ChemosynthesisChemosynthesis• When primary producers turn the

energy in chemicals (like hydrogen sulfide) into carbohydrates.o Mostly bacteriao Found in extreme environments (deep ocean, hot

springs, volcanoes)

2. Heterotrophs2. Heterotrophs• Eat other organisms for food.• Also called consumers

Types of ConsumersTypes of ConsumersClassified 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)

* Put these definitions in the correct bubbles on pg. 5 in the notes.

Energy Flows One Energy Flows One WayWay

• Almost all energy on Earth starts from the sun!

• Energy flows through an ecosystem in a one way direction from producers to consumers

Food ChainFood 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”

Food WebsFood Webs

• Food web- a network of complex interactions formed by the feeding relationships among the organisms of an ecosystem

Algae Plants

Decomposers and Decomposers and Detritivores are Important Detritivores are Important

in Food Websin 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 detrituso 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

Food Web Food Web DisturbancesDisturbances

• Environmental changes can cause changes in a food web

Krill

Think About It…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?

Trophic LevelsTrophic 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

Ecological PyramidsEcological 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

Pyramids of EnergyPyramids 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 heatHow much of the energy available to

the producers is available to the third-level consumers?

Pyramids of BiomassPyramids of Biomass• Biomass is the total amount of living tissue

in a trophic level• Primary Producers will have the greatest

biomass o There must be enough producers to provide

energy for all of the consumers

Pyramids of NumbersPyramids 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

Pyramid of Numbers

Grass

ExampleExample

Phytoplankton = algae that is floating and not attached to something

**Read an arrow as “is eaten by”

ExampleExample

Algae Plants