BIO 2 GO! Interactions of Organisms in an Ecosystem Trophic Level 3524 Niche

Transcription

1 BIO 2 GO! Interactions of Organisms in an Ecosystem Trophic Level 3524 Niche Interrelationships and Interdependencies among different organisms in an ecosystem are affected by factors in the environment. These relationships contribute to the stability of an ecosystem. Upon successful completion of this unit, you should be able to do the following: 1. Explain how energy flows through an ecosystem in terms of trophic levels. 2. Explain how trophic levels and food chains are related. 3. Explain how the amount of energy changes as the trophic levels increase. 4. Describe the role of each of the following in a food chain or food web: a. sun b. producer c. consumer d. decomposer 5. Describe similarities and differences between food chains and food webs. 6. Describe and explain and organisms niche. 7. Distinguish between a niche and habitat. 8. Use the following words in their correct context: Trophic level Producer Consumer Decomposer Herbivore Carnivore Omnivore Food chain Food web Phytoplankton Zooplankton Krill Niche Habitat

2 Trophic Levels 3523 Trophic levels explains how energy flows (moves) through an ecosystem. As you know from before, plants take the energy from the sun and turn it into energy that other organisms can use. This process is called photosynthesis and the energy that is made during photosynthesis is in the form of glucose (a sugar). Animals can then get this energy by eating the plants, by eating other organisms that ate the plants, or by eating both! Every time an organism receives energy from another source, it adds a trophic level. It goes like this Trophic level = Sun--- Producers--Consumer--Consumer--Consumer--Decomposer (herbivore) (carnivore) (carnivore) and/or and/or (omnivore) (omnivore) In the above diagram, the sun begins the process because the sun is the first source of energy. In trophic level 2, a producer (green plant) uses the sun s energy during photosynthesis. In trophic level 3, a carnivore (like a horse) or an omnivore (like a human) eat the plant and receive the plant s energy. At trophic level 3 another carnivore eats the organism in trophic level 2 and receives its energy. In trophic level 4, the organisms, usually animals, receive the energy from what they consumed from trophic level 3. Finally, the decomposers complete the process. So, the organism in trophic level 4 receives energy that started with the sun and photosynthesis. No photosynthesis, no energy. Here s another example: Trophic Level= Sun---grass---cow---human---decomposer

3 Look at this example: Trophic Level= Sun---corn---grasshopper---mouse---hawk---decomposer Note that in every example, the sun is always listed first. The sun is the ultimate source of energy. Also notice that decomposers are always the last. Decomposers return the energy, in the form of waste, to the environment. Food chains can vary in length. Each trophic level receives less of the original amount of energy. REMEMBER THIS!!! As trophic levels increase, the amount of energy they receive decreases. So that is how energy moves through the trophic levels! We can also call this a food chain. Let s look at each piece. REMEMBER THIS!!! A food chain is a diagram that shows the flow of energy through an ecosystem. 1. Producers Producers are PLANTS. Some bacteria and algae are also producers. They take the solar energy from the sun and do photosynthesis in order to turn it into a chemical energy, called glucose! Other organisms then eat the producers. They are on the first trophic level. Question 1: The grocery store has a section in it called the Produce section. What types of things do you find in that section?

4 2. Consumers Consumers are organisms that consume (eat) plants or other animals. We are consumers! We have to eat in order to live. There are three different types of consumers: herbivores, carnivores, and omnivores. Herbivores eat only plants. Examples are deer, giraffes, cows, and horses. They are on the second trophic level. Carnivores eat only meat. They are called secondary consumers because they eat the herbivores. You would find them on the 3 rd trophic level. Some examples of carnivores are snakes, tigers, and wolves. Omnivores eat both plants and meat. You could find them on different trophic levels depending upon what they are eating. Humans are omnivores! (Even though some people are vegetarians, we as a species are classified as omnivores.) Other examples of omnivores are bears and some fish Decomposers are a special type of consumer. They break dead things down so that they can be reused by plants and other organisms. Scavengers are organisms that eat dead things, but they do not break down the organism so they are not considered a decomposer. Vultures are a scavenger. Can you imagine if we did not have decomposers? ALL the things that have ever died since the beginning of time would still be lying around here! You could be stepping on dinosaur bodies every time you walked! Yuck! So you see, decomposers are very important!! Bacteria and fungi are decomposers. Question 2: Below is an example of a terrestrial (land) food chain. Give two more food chains using different organisms. Make one of them an aquatic (ocean) food chain! Ex. Grass caterpillar bird hawk

5 Food webs are many food chains that are all interconnected. In most ecosystems animals eat on more than one trophic level- and writing them down can get really complicated! Food webs show us all the possibilities of how an organism would eat. You don t eat the same thing every day, do you? Here is an example of a terrestrial food web: Wolf Eagle Human Hawk Blue Bird Cow Duck Caterpillar Horses Deer Grass Most ocean food chains begin with very tiny floating plants called phytoplankton. These are found near the ocean's surface where there is plenty of sunlight for photosynthesis (food-making). Phytoplankton is eaten by floating animals called zooplankton. These are tiny animals or larvae of crabs, jellyfish, corals and worms. Zooplankton is food for fish. Bigger fish or mammals eat smaller fish. These bigger fish might include cod, herring, flounder and sharks. Mammals that eat fish would include seals and various types of toothed whales. One type of zooplankton is krill. Krill are tiny shrimp-like creatures. They eat phytoplankton and even other zooplankton.

6 Here is an example of an ocean food chain: Sun's Energy -> Phytoplankton -> Krill -> Humpback Whale Now you try it!! Question 3: Using the example of the ocean food chain above as a starting point, draw an ocean food web. Put in organisms that you are familiar with that live in the ocean. Question 4: In a food chain, where are the producers always found? Question 5: Why are consumers always listed after producers in a food chain?

7 Niche 3524 As we discussed in the section on Diversity, 351, all organisms have a place in the ecosystem. From section 3523 we know about the food chain and food webs and we can see how organisms relate to each other. The functional role an organism plays in the ecosystem is called its niche (pronounced nitch). An organism s niche tells us what it eats, where it sleeps, and all the things organisms do on a daily basis. A niche also tells us about the organisms home, what it needs to survive, (like food and water), and how the organisms reacts with other organisms in the area (are they predator-prey?). REMEMBER THIS!!! An organism s niche refers to its role, (what it needs to survive, what it eats, what eats it, etc.) in the habitat and the community. A niche is also easily remembered if you think of a niche as an organism s job. It adds more information than an organism s habitat. A habitat tells where the organism is likely to be found. Question 6: Select an animal. Explain the habitat and niche for that animal. Question 7: How would you describe your niche? What things do you do every day? What do you eat? Where do you sleep? Describe your niche!

8 Interactions of Organisms in an Ecosystem Trophic Level 3524 Niche SELF TEST Matching 1. Energy pyramid 2. Omnivore 3. Producers A. Organisms that get their food by eating other organisms. B. Organisms that eat only meat. C. Breaks down dead organisms in 4. Carnivore 5.Consumers 6. Habitat the environment. D. Made up of interconnected food chains. E. An organism s role in the environment. 7. Decomposer 8. Food web 9. Phytoplankton 10. Niche F. Organisms that make organic nutrients for an ecosystem using energy from the sun. G. Tiny plant-like creatures that live in the ocean. H. Organisms that eat both plants and meat. I. Where an organism lives. J. Explains the energy flow through an ecosystem. Fill in the Blank decomposers food chain food web trophic herbivores energy 1. The term is given to the bacteria that break down dead tissue. 2. In an ecosystem, decreases at each higher trophic level. 3. Animals known as eat only primary producers. 4. A path of energy through the trophic levels of an ecosystem is called a(n). 5. The interrelated food chains in an ecosystem are called a(n).

9 True or False 1. The lowest trophic level of any ecosystem is occupied by the producers. 2. Omnivores feed only on primary producers. 3. A food chain is made up of interrelated food webs. 4. All organisms in an ecosystem are part of the food web of that ecosystem. 5. The number of organisms in a trophic level is always directly proportional to the amount of energy at that level. 6. Producers are animals. 7. A carnivore eats only plants. 8, Zooplankton is food for larger fish. 9. Decomposers are a special kind of consumer. 10. The sun is the ultimate source of energy for ecosystems. 11. A niche is where an organism lives. 12. A niche tells us what an organism eats and sleeps, among other things. Answer the following: 1. Why are decomposers necessary for the continuation of life on Earth? 2. What is the difference between a food chain and a food web? 3. Explain how a change in the habitat of a species affects the entire ecosystem.

10 Interactions of Organisms in an Ecosystem Trophic Level 3524 Niche Answer Sheet Question 1: The grocery store has a section in it called the Produce section. What types of things do you find in that section? Question 2: Below is an example of a terrestrial (land) food chain. Give two more food chains using different organisms. Make one of them an aquatic (ocean) food chain! Ex. Grass caterpillar bird hawk Here is an example of an ocean food chain: Sun's Energy -> Phytoplankton -> Krill -> Humpback Whale Now you try it!! Question 3: Using the example of the ocean food chain above as a starting point, draw an ocean food web. Put in organisms that you are familiar with that live in the ocean.

11 Question 4: In a food chain, where are the producers always found? Question 5: Why are consumers always listed after producers in a food chain? Question 6: Select an animal. Explain the habitat and niche for that animal. Question 7: How would you describe your niche? What things do you do every day? What do you eat? Where do you sleep? Describe your niche!

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