Food chains, food webs and the transfer of energy

Producers aka Autotrophs A group of organisms that can use the energy in sunlight to convert water and carbon dioxide into Glucose. Energy for all ecological systems begin with producers Example: plants and algae

Producers can be... Phototrophic or chemotrophic VS

Consumers aka Heterotrophs Organisms that do not make their own food They must consume other organisms in order to live Example: rabbits, deer, mushrooms

Scavengers Feed on the tissue of dead organisms (plants and animals) Examples: vultures, crows, shrimp

Herbivores Feed on plants only Examples: cows, elephants, giraffes

Carnivores Feed on only meat Lions, tigers, sharks

Omnivores Feed on both plants and meat Examples: bears and humans

Decomposers Absorb any dead material and break it down to return nutrients to the environment Examples: bacteria and mushrooms

Transfer of Energy When a zebra eats the grass, it does not obtain all of the energy the grass has When a lion eats a zebra, it does not get all of the energy of the zebra

Transfer of Energy The two previous examples of energy transfer show that no organism EVER gets all of the energy from the organism it just ate Only 10% of the energy from one trophic level is transferred, the other 90% is lost Heat, energy to live!

Trophic Levels Energy moves from one organism to another when it is eaten Each step in this transfer of energy is known as a trophic level The main trophic levels are producers, consumers and decomposers

Food Chains The energy flow from one trophic level to the other is known as a food chain It involves: Primary consumers – eat producers Secondary consumers – eat the primary consumers Tertiary consumers – eat the secondary consumers Decomposers – bacteria and fungi that break down dead organisms and recycle the material back into the environment

Food Chain Marine food chain:

Food Web Most organisms eat more than just one organism When more organisms are involved it is called a food web

Food Web The arrows in a food web show the direction of energy flow

Ecological Pyramid Shows the relationship between consumers and producers at different trophic levels in an ecosystem Shows amount of energy at each level

Ecological Pyramid mh