Ecosystem Relationships How Energy Flows Through Ecosystems

Reflection  Take out a paper and use the next five minutes to write down 1-2 arguments FOR vegetarianism.  Think-Pair-Share  Group Discussion

Feeding Relationships in Ecosystems  What relationships are important in ecosystems?  What is an ecosystem?  What is an environment?  What are some ways we can classify the living things in an ecosystem?

Food Chains – An Overview Food Chain Overview Food Chain Overview

Some New Vocabulary…  Trophic levels: –the feeding levels in a food chain or food web.  Producers: –plants that turn radiant energy from the sun into chemical energy for ecosystems. –1 st trophic level  Primary Consumers: –the first consuming organism in a food chain (an herbivore or an omnivore). –2 nd Trophic Level

Some New Vocabulary  Secondary Consumers: –a second consuming organism in a food chain (a carnivore or an omnivore). –3 rd trophic level  Tertiary Consumers: –a third consuming organism in a food chain (usually a top carnivore but can be an omnivore). Ex: ? –4 th trophic level  Detrivores: –an organism that consumes dead material and animal wastes; includes decomposers. –decomposers break down cells and extract remaining energy.

You and Food Chains  Make a list of what you’ve eaten in your last two meals.  For processed foods list all the ingredients that come from living things.  Divide your list into animal matter and plant matter.  Divide the animal matter into herbivores (such as cows) and carnivores (such as tuna). Record omnivores (such as chickens) in both groups.  From your data draw three food chains to which you are linked.

You and Food Chains  What kinds of organisms are at the start of every food chain?  Do any of your food chains have more than three links? Why?  For what species might you become food?  Volunteers to generate a chain?

From Land to Mouth (p. 6)  Group discussion:  Divide the data into producers and consumers.  Which group has the highest energy production on average?  Do plants vary a little or a lot in their energy production? Why?  Is it more efficient for people to eat plant or animal products? Why?

Where Does the Energy Go?  Food energy that is taken in by a consumer is used by that organism.  Only about 10% is converted to new tissues.  Energy is lost to waste and thermal energy.  Photosynthesis?  Cellular Respiration?

Pyramid of Numbers Relative population sizes of each trophic level in an ecosystem.

Pyramid of Numbers  Exceptions

Pyramid of Biomass Shows the relative dry mass in grams per square metre (g/m 2 ) of organisms in a food chain.

Pyramid of Biomass

Pyramid of Energy Flow Shows the decrease in energy that is available to each successive trophic level.

Which Should We Use?  All are useful in different ways and tell us different things about the feeding relationships in a food chain.  Build your own pyramid (your choice) for a pond ecosystem.

Questions to Consider  To study the transfer of food energy from dogs to fleas, which pyramid would you use?  Ecosystem A has a plant biomass of ‘X’. Ecosystem B has a plant biomass of ‘2X’. Suggest which ecosystem has the largest populations of consumers. Why?

Food Chains vs. Food Webs Disruptions Ripple Effects Food chains show linear feeding relationships.

Food Chains vs. Food Webs Non-linear feeding relationships. More than one feeding option. Disruptions? Ripple effect? Which is a better alternative? Food chain or food web? Which do you think is more common in nature?

Dibbles, Dinks, Woks & Dorgs  Please answer all questions and hand in at the end of class or at the beginning of next class.