Food Chains Food Chains &&

Food WebsFood Webs

Food chainFood chain

Food chainFood chain: A model that shows how : A model that shows how energyenergy and and mattermatter move through an move through an ecosystemecosystem

AcornAcorn SquirrelSquirrel Red-tailed Red-tailed hawkhawk Arrows point to the Arrows point to the CONSUMERCONSUMER Need to start with a Need to start with a PRODUCERPRODUCER Only up to 5 organisms in a food chain (only Only up to 5 organisms in a food chain (only

shows 1 feeding relationship at a time)shows 1 feeding relationship at a time)

EnergyEnergy

Energy (E)Energy (E): the ability to do work: the ability to do work In food chains/webs, all energy (E) comes from In food chains/webs, all energy (E) comes from

the Sunthe Sun Sun’s E trapped by producers & convert to Sun’s E trapped by producers & convert to

chemical E (in photosynthesis) <chemical E (in photosynthesis) <11stst law of law of thermodynamicsthermodynamics>>

The E moves from producers to consumers The E moves from producers to consumers along the food chain (only moves in 1 direction)along the food chain (only moves in 1 direction)

Some energy is “lost” along the way in the form Some energy is “lost” along the way in the form of heat <2of heat <2ndnd law of thermodynamics> law of thermodynamics>

Rule of 10%Rule of 10%

Only 10% of the energy gets passed on to Only 10% of the energy gets passed on to the next level of the food chain. 90% of the the next level of the food chain. 90% of the energy is lost as heat or used by the energy is lost as heat or used by the organismorganism In our example of the food chain, if the In our example of the food chain, if the

acorns were 100 calories…how many of acorns were 100 calories…how many of those 100 calories would the red-tailed those 100 calories would the red-tailed hawk get?hawk get?1 calorie!1 calorie!

MatterMatter

MatterMatter: is anything that has mass and : is anything that has mass and takes up spacetakes up space Atoms are the “building blocks” of matterAtoms are the “building blocks” of matter 4 most important elements in living 4 most important elements in living

organisms: hydrogen (H), oxygen (O), organisms: hydrogen (H), oxygen (O), nitrogen (N), and carbon (C)nitrogen (N), and carbon (C)

The Earth has a limited amount of The Earth has a limited amount of matter, so matter must be matter, so matter must be RECYCLEDRECYCLED!!!!

Carbon CycleCarbon Cycle

Nitrogen CycleNitrogen Cycle

Water CycleWater Cycle

Remember…Remember… Energy FLOWS through the Energy FLOWS through the

ecosystemecosystem Matter RECYCLES in the ecosystemMatter RECYCLES in the ecosystem

Trophic LevelsTrophic Levels

Trophic level: the feeding level in the Trophic level: the feeding level in the ecosystemecosystem PP = Producer = Producer 11 = 1 = 1stst level consumer (feeds on producers) level consumer (feeds on producers) 22 = 2 = 2ndnd level consumer (feeds on 1 level consumer (feeds on 1stst level con.) level con.) 33 = 3 = 3rdrd level consumer (feeds on 2 level consumer (feeds on 2ndnd level con.) level con.) Levels can go higher (not usually above 5)Levels can go higher (not usually above 5) Possible for an organism to be on more than 1 Possible for an organism to be on more than 1

trophic level (in other food chains or food webs)trophic level (in other food chains or food webs)

ExampleExample

Wetland Food ChainWetland Food Chain

Phytoplankton

Blue gill

Heron

Alligator

(P)

(1)

(2)

(3)

Food WebsFood Webs

Food webFood web: a pattern of feeding in an : a pattern of feeding in an ecosystem consisting of ecosystem consisting of interconnected and branching food interconnected and branching food chainschains All the same rules apply (arrows, All the same rules apply (arrows,

trophic levels, etc)trophic levels, etc)