FOOD CHAINS & WEBS Introduction to ENERGY FLOW

the ultimate energy source

Energy Flow The sun’s energy flows into organisms that can change the sunlight into food then into organisms that eat them. This flow is: sunlight producer consumer 1 consumer 2

PRODUCERS What are producers? Autotrophs that trap solar energy into organic molecules during photosynthesis; can produce their own food Ex. Plants, algae and some bacteria sunlight producer consumer 1 consumer 2 ``

CONSUMERS What are consumers? Heterotrophs that eat other organisms to obtain energy Examples: deer, rabbits, cows, mice, lions, humans, hawks, snakes sunlight producer consumer 1 consumer 2

HERBIVORES What are herbivores? Organisms that eat plants Primary Consumers Ex. Cows, caterpillars, bunnies sunlight producer consumer 1 consumer 2

CARNIVORES What are carnivores? Organisms that eat meat (other animals/consumers) Secondary Consumers Ex. tigers, wolves, snakes, hawks sunlight producer consumer 1 consumer 2

TOP CARNIVORES What is a top-level carnivore? Top-level carnivores eat secondary consumers; usually nothing feeds on them consumer 3 Ex. killer whale eating a sea lion or hawk eating a snake. sunlight producer consumer 1 consumer 2

OMNIVORES What are omnivores? Consumers that eat both plants and animals Primary and Secondary Consumers Ex. bears and humans

Where do all the dead things go? They are eaten. YUMMMM! They decay. SMELLY! detritivore decomposer

Detritivore vs Decomposers Decomposers breakdown (decay) organic matter and feed on it Detritivores eat the remains of dead plants and animals Crabs, mites, earthworms, snails Bacteria & fungi

Detritivore vs Decomposers What is a scavenger? A scavengers is a type of detritivore that feeds on carrion (dead animal remains). Ex. vultures, sharks, maggots, hyenas Detritivores and Decomposers When is a detritivore called a scavenger? Detritivores are scavengers when they feed mainly on carrion (dead animals). Ex. vultures, sharks, maggots, hyenas Planetware.com, photo by Jim Steinhart http://www.planetware.com/photos/IND/IND203.HTM

Detritivore vs Decomposers Why would they be called the environmental “recyclers”? They decompose excrement, dead bodies and leaf litter, returning nutrients to the physical environment. sunlight producer consumer 1 consumer 2 decomposer consumer 3

Food Chain The series of steps in which organisms transfer energy by eating and being eaten sunlight producer consumer 1 consumer 2

Food Chains & Food Webs The steps in the transfer of energy from organism to organism in feeding relationships are called Trophic Levels. producer consumer 1 consumer 2 consumer 3

Food Chains & Food Webs Name the number of the trophic levels in the food chain below. How do the trophic level numbers correspond with the “eating terms”? producer consumer 1 consumer 2 consumer 3 1 Trophic Level 2 4 3

Food Chains & Food Webs What important energy transfer is not shown in a food chain? Why is it that some energy is lost from one level to the next level? How much energy is actually passed on to the next level? (rule of thumb) producer consumer 1 consumer 2 consumer 3

Food Chains & Food Webs What vital “recycler” is not shown in this food chain? Upon which organism(s) would it feed? decomposer producer consumer 1 consumer 2 consumer 3

Food Chains & Food Webs If all of the snakes in this chain died, what would happen to the hawk? To the decomposers? decomposer producer consumer 1 consumer 3 consumer 2

Food Chains & Food Webs Most organisms feed on more than one trophic level and feed on several different species at each trophic level. This is a food web. Food Chains & Food Webs Most organisms feed on more than one trophic level and feed on several different species at each trophic level.

Ecological Pyramids Introduction to ENERGY FLOW

Ecological Pyramids Grass (10,000 kcal) Grasshopper (1,000 kcal) Frog (100 kcal) Snake (10 kcal) Hawk (1 kcal) 1 2 3 4 5 Instead of representing trophic levels in a food web, an ecological pyramid can be used. Ecological Pyramids Instead of representing trophic levels in a food web, an ecological pyramid can be used.

Ecological Pyramids Does this pyramid represent a food chain or web? 5 Grass (10,000 kcal) Grasshopper (1,000 kcal) Frog (100 kcal) Snake (10 kcal) Hawk (1 kcal) 1 2 3 4 5 Ecological Pyramids Does this pyramid represent a food chain or web? A chain as there is only one eating path. How could this pyramid be changed to represent a food web? Different species of organisms could be added at each level to show more eating “opportunities for the organisms above it. Broaden the discussion by asking “What organisms could you add at each trophic level for a web??

Ecological Pyramids What do the big numbers represent? Grass (10,000 kcal) Grasshopper (1,000 kcal) Frog (100 kcal) Snake (10 kcal) Hawk (1 kcal) 1 2 3 4 5 What do the big numbers represent? What does the kcal mean? Ecological Pyramids What do the big numbers represent? The trophic levels. Have them identify the type of organism at each level. What does the kcal mean? It stands for kilocalories, a measurement of energy.

Pyramid of Energy What happens to the energy as you go up? Grass (10,000 kcal) Grasshopper (1,000 kcal) Frog (100 kcal) Snake (10 kcal) Hawk (1 kcal) 1 2 3 4 5 How much energy is available for the next level? (What %) Ecological Pyramids What happens to the energy as you go up? It gets less and less; lost in heat energy or used in metabolism. What is the energy loss between levels? The rule of thumb is 10% (although it is an average across levels and chains.) No trophic level can contain more energy than the level below.

Pyramid of Energy Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web. Grass (10,000 kcal) Grasshopper (1,000 kcal) Frog (100 kcal) Snake (10 kcal) Hawk (1 kcal) 1 2 3 4 5

Pyramid of Energy

Pyramid of Energy

Ecological Pyramids How is this pyramid different from the previous ones? What could the multiple pictures of the species at each level represent? Ecological Pyramids How is this pyramid different from the previous ones? It shows multiple pictures of each species at the different trophic levels. What could the multiple pictures of the species at each level represent? They could represent the total number of organisms of each species or their total biomass.

Pyramid of Biomass Biomass-the total amount of living tissue within a given trophic level. A pyramid of biomass illustrates the relative amount of living organic matter available at each trophic level

Pyramid of Biomass What information would this pyramid include if it were a pyramid of biomass? How do they get a number total for the biomass of a population? Ecological Pyramids What information would this pyramid include if it were a pyramid of biomass? It would have the total biomass at each level or it would have a key for how much biomass was represented by each picture. How do they get a number total for the biomass of a population? The total mass of the organisms is determined by drying and weighing a sample number of organisms at each level and then calculating the total mass for the species at each level.

Pyramid of Biomass

Pyramid of Biomass

Pyramid of Numbers A pyramid of numbers shows the relative number of individual organisms at each trophic level.

Pyramid of Numbers What information would this pyramid include if it were a pyramid of numbers? How do they get a number total for a population of organisms? Ecological Pyramids What information would this pyramid include if it were a pyramid of numbers? It would have the total population at each level or it would have a key for how organisms were represented by each picture. How do they get a number total for a population of organisms? The population is determined by counting the organisms of a species in a sample portion at each level and then calculating an average for the total area.

Pyramid of Numbers

Pyramids of Aquatic Ecosystems Numbers Biomass Energy Pyramids of Aquatic Ecosystems Numbers - Follows the normal pattern of having many more phytoplankton at TL1 Biomass - The phytoplankton reproduce a a rate only just slightly higher than the rate at which they are eaten. Since they are so small and weigh so little there is a very small biomass. Energy - Follows the normal pattern of having much more energy available at TL1 Pyramid of biomass in aquatic ecosystems (ocean & fresh) and some terrestrial ecosystems such as the pyramid of numbers for the temperate forest. Because the trees are so large their numbers are small compared to the number of organisms at the higher trophic levels. Phytoplankton are microscopic and weigh very little

Pyramids of Temperate Forests Numbers Biomass Energy Trees are huge but not as numerous as many smaller forest creatures. Pyramids of Aquatic Ecosystems Numbers - In the temperate forest, the trees are huge but smaller in number compared to the grasses in a prairie and so are fewer compared to the number of organisms at the higher trophic levels. Biomass - Follows the normal pattern of having much more mass at TL1 from the huge trees. Energy - Follows the normal pattern of having much more energy available at TL1