Food Chains and Levels of Organization in Ecology

Levels of Organization in Ecology Species - Group of organisms so similar to one another that they can breed and produce fertile offspring. Population - Groups of individuals that belong to the same species and live in the same area. Communities - Assemblages of different populations that live together in a defined area.

Levels of Organization in Ecology Ecosystem - Collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment. Biome - Group of ecosystems that have the same climate and similar dominant communities.

Levels of Organization in Ecology Biosphere - Contains the combined portions of the planet in which all of life exists, including land, water, and air, or atmosphere. It extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean.

Levels of Organization in Ecology Individual → Species → Population → Community → Ecosystem → Biome → Biosphere

Food Chain vs. Food Web Food Chains follow just one path as animals find food. 2. Food Webs show how plants and animals are connected in many ways to help them all survive.

What Do Food Chains and Food Webs Demonstrate? Both food chains and food webs show the flow of energy in an ecosystem. Energy flows from the leaf to the mouse Energy flows from the snake to the hawk

Trophic Levels Trophic levels - corresponds to the different levels or steps in the food chain. The feeding position in a food chain such as primary producers, herbivore, primary carnivore, etc. Green plants form the first trophic level, the producers. Herbivores form the second trophic level Carnivores form the third and even the fourth trophic levels.

Food Chains Always Begin With Plants Photosynthesis – process used by plants that traps the sun’s energy and use it to make food Producer – organism that can use the sun’s energy to make its own food.

Food Chains/Webs Always Begin With Plants

Eat and Be Eaten Consumers – organisms that cannot make their own food; depend upon producers. Four types of consumers Herbivores - eat plants Carnivores – eat animals Omnivores – eat both plants and animals Decomposer – breaks down dead organic matter to obtain energy Detritivores – feeds on plant and animal remains (crab, earthworm)

Decomposers/Detritivores Decomposers – feeds on the waste products or bodies of other dead organisms (both plants and animals)   Also a consumer Includes: mostly bacteria and fungus maggots dung beetles earth worms sow bugs Without them there would be a lot of dead bodies lying around!

Leeches and maggots are now classified as FDA- approved medical devices — the first live animals to earn that distinction.

Niche Niche – an organism’s niche describes its role or job in the ecosystem The niche describes the position of the organism in the food chain Can be compared to a person’s occupation

What is the niche of these animals?

Other Food Chain Terms Primary Consumer– first consumer (also called first-order consumer) Secondary Consumer– second consumer (also called second-order consumer) Tertiary Consumer- third consumer (also called third-order consumer)

Your Turn!

Other Vocabulary Autotroph - makes its own food Heterotroph - does not make its own food

How Much Energy is Passed On? Only 10% is passed on to the next trophic level The other 90% is lost/given off as heat

.01% .1% 1% 10% 100%

If a nation is starving, what should they eat? Let’s think about the starving regions in Africa. Should they eat producers or consumers? Grains → Cows 100% Energy 10% Energy

If a nation is starving, what should they eat? If they eat cows, 90% of the original energy is lost! Less people can be supported with the field of grain. They should eat grain!

You Try It! Create a food chain. Draw and color at least 5 organisms. Be sure to include a decomposer as one of the organisms. Label each organism by their level in the food chain (producer, primary consumer, etc). Make sure you include arrows and that they are drawn in the correct direction. Next to the arrows indicate the percent of energy that is passed on from the previous organism to the next organism.

Food Chains: Matter and Energy As you go along a food chain, the matter and energy decreases. This can be represented in a pyramid. .1% Energy 1% Energy 10% Energy 100% Energy Grass → Rabbit → Snake → Hawk

Pyramids Pyramids are larger at the bottom…more matter and energy are at the bottom of the pyramid!

Ecological Pyramids Ecological Pyramid- diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.

Two Types of Ecological Pyramids Pyramid of Biomass – Represents the biomass at each trophic level Pyramid of Numbers – Represents the number of organisms at each trophic level

Pyramid of Biomass Biomass – total amount of living tissue within a trophic level Usually expressed in grams per unit area. As you go along a food chain, the amount of matter decreases!

Pyramid of Numbers As you go further down a food chain, the numbers of organisms decrease because there is less energy available!

Other Pyramid of Numbers If you have a large producer (such as a tree), the pyramid of numbers may look diamond in shape. A large tree supports a lot of organisms.

As you go further down a food chain, the numbers of organisms decrease because there is less energy available!

Think About It Let’s think of a food chain found at Seven Lakes. Grass → Rabbits → Coyotes Lots of grass on Seven Lakes 1000 There are quite a few rabbits on the Seven Lakes Campus 10 A few coyotes may roam onto Seven Lakes occasionally 1

Population Changes in Food Chains What would happen to this bird if the population of caterpillars decreases?

Population Changes in Food Chains What would happen to this bird if the population of caterpillars decreases? The bird population would decrease also because he would have less food.

Population Changes in Food Chains What would happen to the bee population if the flower population exploded?

Population Changes in Food Chains What would happen to the bee population if the flower population exploded? The bee population would also increase.

Population Changes in Food Chains If the snake population decreases, what would happen to the other organisms in the food chain?

Population Changes in Food Chains If the snake population decreases: The hawk population decreases also (less food) The frog population increases (less predators eating them) More frogs eating the grasshoppers, so less grasshoppers

Now Try It Yourself http://ecokids.earthday.ca/pub/eco_info/to pics/frogs/chain_reaction/index.cfm#