Trophic Levels, Energy transfer and Pyramids
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.
Food Chains The energy flow from one trophic level to the other is known as a food chain Producers are at the first TROPHIC LEVEL Primary Consumers are the SECOND TROPHIC LEVEL Secondary consumers are at the THIRD TROPHIC LEVEL
Trophic Levels (feeding levels) 3 2 1
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
Food Webs Food webs show ALTERNATIVE PATHWAYS other possible pathways through which an organism can obtain energy
Trophic Level Grass Mouse Grasshopper Frog Owl Hawk Producer, primary consumer, secondary consumer, tertiary consumer?
Trophic Level Producer, primary consumer, secondary consumer, tertiary consumer Producer Grass 1 st Mouse 2 nd Primary consumer Grasshopper 2 nd Primary consumer Frog 3 rd Secondary consumer Owl 3 rd and 4 th Hawk 3 rd Secondary and tertiary consumer Secondary consumer
Transfer of Energy When a lion eats a zebra, it does not get all of the energy from the zebra. Energy lost is usually in form of heat lost from chain “link” to “link” is significant!
qfrom grass to sheep, loss is about 90%! HEAT 90% 100% Energy Available 10% Original Energy! 1% Original Energy!
Energy lost from one trophic level (energy level) to the next level can be represented by a pyramid 4⁰ CONSUMERS 3 CONSUMERS 2 CONSUMERS 1 CONSUMERS PRODUCERS
¨ 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)
ENERGY PYRAMID 1 J 100 J 1, 000 J 10, 000 J
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 6 th level would have very little energy to keep it alive
Pyramid of Numbers • Shows the numbers of individual organisms at each trophic level in an ecosystem. tertiary consumers 5 secondary consumers 5000 primary consumers 500, 000 producers 5, 000 • A vast number of producers are required to support even a few top level consumers.
Biomass pyramid • Biomass is a measure of the total dry mass of organisms in a given area. tertiary consumers 75 g/m 2 150 g/m 2 secondary consumers primary consumers producers 675 g/m 2 2000 g/m 2