Food Chain & Food Web

• A food chain shows HOW each living thing gets its food.

• A food web consists of several food chains

• A food web = multiple food chains

PRODUCERS: plants at the bottom of the food chainPRIMARY CONSUMER: eats the producersSECONDARY CONSUMER: eats primary consumerTERTIARY CONSUMER: eats secondary consumer

DECOMPOSERS: fungi, bacteria speed up the decaying process of dead animals and plants

Sun=The source of energy

Test your understanding

• What does stability of an ecosystem depends on? (Only address the food chain and food web aspect):

• Ans: the stability of its producers and decomposers

• Explain why stability of producers and decomposers are important:

Illustrate an aquatic food chain and identify producers, various consumer

shark

algaefish shark whale

phytoplankton Zoo plankton

Zoo plankton

fish shark

Phytoplankton/Zooplankton (Plankton), Clams,

Whelks, Turtles, and Sharks

• Phytoplankton/Zooplankton (Plankton), Clams, Whelks, Turtles, and Sharks. 

• See the next slides for each part of the food chain.   • Food Chain: Plankton • Plankton include microscopic plant and animal organisms that float

or drift in great numbers in the ocean. Plankton are the start of most oceanic food chains.

• There are many species of plankton and each has a characteristic shape. Plankton may be phytoplankton (plant-like organisms - producers) or zooplankton (animal-like organisms - consumers).

• Loggerhead turtles eat plankton when they are very young and small juveniles. Clams also eat plankton

FOOD CHAIN ORDER

PRODUCERS

PRIMARY CONSUMERS

SECONDARY CONSUMERS

TERTIARY CONSUMERS

PLANTS

HERBIVOREDEER, BUNNY

CARNIVORESWOLVES, SNAKES

CARNIVORESLIONS, EAGLES

Categories in food chain

What do decomposers eat?• Typically, food webs go like this:

PRODUCER

CONSUMER(HERBIVORE)

CONSUMER(CARNIVORE)

CONSUMER(OMNIVORE)

DECOMPOSER

remember: decomposers receive energy from all other organisms in an ecosystem

ENERGY IN AN ECOSYSTEM

•What is an energy pyramid?

•What is a trophic level?

ENERGY PYRAMIDS• Energy pyramids show the transfer of energy

through a food chain– the pyramid is made of levels

GRASS

SNAIL

FISH

                                                         

                        

1. The further along the food chain you go, the less food (and hence energy) remains available.

Where do producers get their energy from?

Which of the above categories has the highest food energy?

TROPHIC LEVEL = PYRAMID OF ENERGY

Why is there less food energy available at the top of the pyramid?• Because most of the energy gets lost into

the environment at each link.

• 90 % of the energy is lost to the environment as HEAT

• 10% of the energy is transferred

Energy pyramid

A producer receives all the energy in an ecosystem

•

100% Producers

Primary consumers

Secondary consumers

10%

1%

TROPHIC LEVELS• A trophic level is:

– a step in the transfer of energy through an ecosystem

– a level in an energy pyramid

Producers

Primary Consumers

Secondary Consumers

• Different trophic levels:– producer– consumer

• primary, secondary, tertiary, quaternary

100 %

10 %

1 %

ENERGY PYRAMIDS• Energy is lost with each transfer in a food chain

– 90% of the energy available at a level is released to the environment as heat

– 10% of the energy is incorporated or used

Only about Only about 10% of the 10% of the

energy from energy from a previous a previous

level is level is passed on passed on

to the to the consumerconsumer

FOOD WEBS• A food web shows all feeding relationships in

an ecosystem (made of many food chains)

Which one will be impacted most by removing coyote

grass

rabbit

coyote

lion

hawk

Check for understanding

• what is the source of energy for producers?• what is the source of energy for primary

consumers?• what is the source of energy for decomposers?• omnivores eat both _______ and _______• herbivores eat ________• carnivores eat _______________• bacteria, fungi are examples of __________

• percent of energy for primary consumers is _______ %

• percent of energy for secondary consumers is ________ %

• from one link to the other link in a food chain only 10% of the energy is transferred the rest of the energy (the other 90%) is lost as _________. This results in _________ organism at the lower levels and __________ organisms at the higher level

population

• Population is a group of same species occupying the same area (location)

• Or:

• A population is all the organisms that both belong to the same species and live in the same geographical area.

community

• A community is a group of different species (organisms) interacting with each other and sharing (populating) the same location (area)

• a community is a group of interacting species sharing a populated environment

Ecosystem

• A community and its environment

• Ecosystem = biotic + abiotic

• Ecosystem = community + environment

1. An organism’s 1. An organism’s nicheniche is what it does is what it does (job or role) in its ecosystem(job or role) in its ecosystem2.2.NicheNiche is how an is how an organism uses itsorganism uses its environmentenvironment3.3.Organisms with Organisms with different nichesdifferent niches

can can divide up the environmentdivide up the environment that that they are inthey are in

HABITAT & NICHE• An organism’s habitat is where it lives

(home or natural environment)– examples?

• When an organism’s habitat or niche are

changed, it can lead to extinction (the local or global disappearance of a species)– niche or habitat competition

biodiversity

• Watch the biodiversity video

Which ecosystem is more biodiverse? Explain your answer

• Ecosystem A: has three types of plants and 10 types of consumers

• Ecosystem B: has two types of plants and 6 types of consumers

• Biodiversity = variety of species + quantity• Ecosystem C: has 20 grass, 10 rabbits, 4

snakes• Ecosystem D: has 50 grass, 20 rabbits, 10

snakes

• Biodiversity is:– the sum total of different kinds of organisms– the variety of living organisms in an ecosystem

• ∆s (changes) in habitat affect biodiversity– ∆ = effect on biodiversity– e.g. natural disaster = decrease in biodiversity

• When an ecosystem has more biodiversity:– it is more stable – It is more resilient

BIODIVERSITY IN ECOSYSTEMS

BIODIVERSITY IN ECOSYSTEMS• Two types of organisms based on how they obtain

energy:

– autotrophs – using the sun energy, make their

own food

• Producers

• Do photosynthesis

– heterotrophs - get energy from other organisms

• decomposers (recyclers of plant/animal

waste)

• consumers are heterotrophs and are part of

the cycle• The stability of an ecosystem depends

on the stability of its producers and

decomposers. It is very important b/c

they produce and recycle organic material

P

D

DECOMPOSERS

• Decomposers recycle organic material through an ecosystem

Which ecosystem is more biodiverse? Explain your answer

• Ecosystem A: has three types of plants and 10 types of consumers

• Ecosystem B: has two types of plants and 6 types of consumers

• Biodiversity = variety of species + quantity• Ecosystem C: has 20 grass, 10 rabbits, 4

snakes• Ecosystem D: has 50 grass, 20 rabbits, 10

snakes

Consumers

• Primary consumers =

• Secondary & Tertiary consumers =

Mini quiz

• what is the benefit of decomposers

• how do decomposers benefit the quality of the soil?

• the job or role of an organism in the environment is called ________

• how organisms use their environment is called ________

• organism with different niches can _______ ___ an environment that they are living in. So they can live in the same environment

• population is made of _______• communities are made of different _________• species, _________, community, ecosystem

(environment and the community)• ________, population, community,

ecosystem

• bacteria, fungai are examples of __________

• __________ get their energy directly from the environment and make their food examples are: trees, flowers, algae.

• _______ can not make their own food. examples: lions, decomposers, human

• sun is the source of _________• total sum of all kinds of different

organisms living in an ecosystem is called ______

TYPES OF CONSUMERSYou are what you eat!You are what you eat! Eat herbs (plants)? You’re an Eat herbs (plants)? You’re an herbivoreherbivore..

Herbivores are consumers that eat only producers Herbivores are consumers that eat only producers

Eat carne (meat)? Eat carne (meat)? You’re a You’re a carnivorecarnivore.. Carnivores are consumers Carnivores are consumers

that eat only consumersthat eat only consumers Eat everything (plants + meat)? Eat everything (plants + meat)?

You’re an You’re an omnivoreomnivore.. Omnivores are consumers that eat Omnivores are consumers that eat

producers and consumersproducers and consumers

FOOD CHAINS & WEBS

What are food chains and food webs?

How does energy move through an ecosystem?

What is an organism’s habitat and niche?

FOOD CHAINS• A food chain is a

sequence of energy transfer from one organism to another

– energy flows from

producers to

consumers

– arrows follow the

energy (from what is

eaten to what is

eating)

FOOD WEBS A food web shows all feeding relationships in A food web shows all feeding relationships in

an ecosystem (made of many food chains)an ecosystem (made of many food chains)

FOOD WEBS• Typically, food webs go like this:

PRODUCER

CONSUMER(HERBIVORE)

CONSUMER(CARNIVORE)

CONSUMER(OMNIVORE)

DECOMPOSER

remember: remember: decomposersdecomposers receive energy receive energy from all other from all other organisms in organisms in an ecosysteman ecosystem

FOOD CHAINS AND WEBS Practice! Draw a food Practice! Draw a food

chain that includes the chain that includes the following organisms:following organisms: grasshoppergrasshopper mousemouse grassgrass owlowl

Now label the organisms Now label the organisms as producers, consumers as producers, consumers (which type?), or (which type?), or decomposersdecomposers PRODUCER

CONSUMER(HERBIVORE)

CONSUMER(CARNIVORE)

CONSUMER(CARNIVORE)

ENERGY IN AN ECOSYSTEM

What is an energy pyramid?

What is a trophic level?

ENERGY PYRAMIDS• Energy pyramids show the transfer of energy

through a food chain– the pyramid is made of levels

GRASS

SNAIL

FISH

ENERGY PYRAMIDS• Energy is lost with each transfer in a food chain

– ~90% of the energy available at a level is released to the environment as heat

– ~10% of the energy is incorporated or used

Only about Only about 10% of the 10% of the

energy from energy from a previous a previous

level is level is passed on passed on

to the to the consumerconsumer

100,000 J

ENERGY PYRAMIDS• The energy pyramid is

shaped that way to show:– producers form the

base of the pyramid– there are fewer

organisms at the top and there is less energy at the top

– there are more organisms and energy at the bottom

100 %

10 %

1 %

0.1 %

TROPHIC LEVELS• A trophic level is:

– a step in the transfer of energy through an ecosystem

– a level in an energy pyramid

Producers

Primary Consumers

Secondary Consumers

Different trophic levels:Different trophic levels: producerproducer consumerconsumer

• primary, secondary, primary, secondary, tertiary, quaternarytertiary, quaternary

100 %

10 %

1 %

ENERGY PYRAMIDS• Practice!

If 100% of the energy is available at the first trophic level, what percentages of the energy are available at the second and third trophic levels?

100%

10%

1%

ENERGY IN AN ECOSYSTEM MINI - QUIZ!

All organisms in an ecosystem need _______ from food to live. An energy ________ shows how much food energy is passed from one ________ to another through food chains. __________ have the largest spot at the base of the pyramid. Altogether, only about _____ of the food energy at each level gets passed up to the next level.

energyenergypyramidpyramid

ProducersProducers10%10%

organismorganism