FOOD CHAINS FOOD WEBS ECOLOGICAL PYRAMIDS October 22, 2014 Miss Mathieu Who eats whom or what?
FOOD CHAINS Grass Rabbit Fox Food chains show: Ø What eats what Ø How energy is passed through an ecosystem The arrows show the direction the energy is flowing All energy in the food chain comes from the SUN – it is the sole course of energy of all life
WHAT IS ALWAYS AT THE BOTTOM OF THE FOOD CHAIN? Why? 1. Producers are the only organisms that can convert the sun’s energy into food 2. All living things depend on producers for food
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FOOD CHAIN TERMS A TROPHIC LEVEL tells you the position an organism holds in a food chain. - Note: matter and energy are always ‘lost’ as urine, feces, and heat energy at each trophic level. PRIMARY (1°) CONSUMERS feed at the first trophic level above the producers. SECONDARY (2°) CONSUMERS eat primary consumers.
FOOD CHAIN TERMS TERITARY (3°) CONSUMERS eat secondary consumers. QUATERNARY (4°) CONSUMERS feed at the fourth trophic level above the producers. TOP CARNIVORES are animals that are not hunted for food by any other animal in the ecosystem. 1 s t LEVEL CARNIVORES are the carnivores that consume herbivores.
EXAMPLE FOOD CHAIN 4 th trophic level Great Horned Owl Tertiary (3°) Consumer (third-order consumer) (top carnivore) 3 rd trophic level Long-tailed Weasel Secondary (2°) Consumer (second-order consumer) (1 st level carnivore) 2 nd trophic level Jackrabbit 1 st trophic level Grass Primary (1°) Consumer (first-order consumer) (herbivore) Producer (autotroph)
FOOD WEB Food webs are more complex, showing more interrelationships. They give a more accurate picture of the ecosystem. They are made of many food chains and have multiple energy paths.
AS A CLASS. . Identify: 1. Trophic Levels 2. The primary producer 3. Primary Consumers 4. Secondary Consumers 5. Tertiary Consumers 6. Quaternary Consumers 7. Top Carnivore
FOOD WEB Answer the questions on the board with your partner
FOOD CHAIN VERSUS FOOD WEB FOOD CHAIN - just one path of energy FOOD WEB - many possible energy paths - contains many food chains
ECOLOGICAL PYRAMIDS show relationships between trophic levels. They are another way of showing food chains. Pyramids are used to compare the total numbers, biomass, or energy at each trophic level within the ecosystem.
PYRAMID OF NUMBERS Pyramid of Numbers shows the number of species at each trophic level.
PYRAMIDS OF BIOMASS Biomass Pyramid shows the total amount of living tissue available at each trophic level
PYRAMID OF ENERGY Trophic Efficiency is the amount of energy transferred from one trophic level to the next. Only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level. 10 kcal Largemouth bass 100 kcal Shiners 1000 kcal Algae
WHAT IS HAPPENING TO THE ENERGY AS IT MOVES UP THE FOOD CHAIN?
PRACTICE Calculate the trophic efficiency of the following energy pyramids:
ENERGY PYRAMIDS SHOW Amount of available energy decreases higher consumers It takes a large number of producers to support a small number of primary consumers It takes a large number of primary consumers to support a small number of secondary consumers
WORKSHEET WITH PARTNER Spend the remainder of the class working on the provided worksheet with a partner. Each student should complete their own sheet Show Miss Mathieu when you are finished! Keep your own copy in your binder for a reference on food chains, food webs, and food pyramids when you are studying for your unit test