food webs and trophic levels
TRANSCRIPT
Vocabulary Trophic Levels – is the position an
organism occupies in a food chain. It refers to food or feeding.
Apex predator – top level predators with few or no predators of their own.
Detritavore – feeds on dead organisms, helps with decomposition
Review Vocab – carnivore, omnivore, herbivore, scavenger, decomposer
Food ChainsThe energy flow from one trophic level to the
other is know as a food chainProducers are at the first TROPHIC LEVELPrimary Consumers are the SECOND TROPHIC
LEVELSecondary consumers are at the THIRD
TROPHIC LEVELTertiary consumers are at the FOURTH
TROPHIC LEVEL In some ecosystems you can go out to
Quaternary consumers
Food Web
Most organisms eat more than JUST one organism
When more organisms are involved it is know as a FOOD WEB
Food webs are more complex and involve lots of organisms
Trophic Level Producer, primary consumer, secondary consumer, tertiary consumer
Grass 1st Producer
Mouse 2nd Primary consumer
Grasshopper 2nd Primary consumer
Frog 3rd Secondary consumer
Owl 3rd and 4th Secondary and tertiary consumer
Hawk 3rd Secondary consumer
Transfer Between Ecosystems If an organism that lives in a terrestrial
ecosystem consumes an organism in an aquatic (or aquatic to terrestrial) energy is transferred between the two.
Ex. Bear eats a fish (energy from aquatic to terrestrial) or fish eats a caterpillar (energy from terrestrial to aquatic)
Transfer of EnergyWhen a lion eats a zebra, it does
not get all of the energy from the zebra.
Energy lost is usually in form of heat
Energy lost from chain “link” to “link” is significant!
from grass to sheep, loss is about 90%!
10% Original Energy! 1% Original
Energy!
100% Energy Available
HEAT90%
HEAT90%
Energy lost from one trophic level (energy level) to the next level can be represented by a pyramid
PRODUCERS
1° CONSUMERS
2° CONSUMERS
3° CONSUMERS
4⁰° CONSUMERS
♦ Each level above only gets 10% of the energy from below
− Ex: 10,000 J of producers (plants) only give 10% of energy to primary consumers> 1,000 J to primary consumers (snails,
minnows, dragonflies)> 100 J to secondary consumers (small fish)> 10 J to tertiary consumers (big fish) > 1 J to quaternary consumers (fish hawk)
Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)
Usually no more than 5 trophic levels since 6th level would have very little energy to keep it alive
Ecological Pyramid
• Which level has the most energy?• Which level has the most organisms?• Which level has the least organisms?• Which level has the least energy?
Pyramid of Numbers
• Shows the numbers of individual organisms at each trophic level in an ecosystem.
tertiaryconsumers
secondaryconsumers
primaryconsumers
producers
5
5000
500,000
5,000,0005,000,000producers
• A vast number of producers are required to support even a few top level consumers.